spore: profile id: steel-4340 spore_version: '0.2' family: carbon-and-alloy-steels name: Alloy steel AISI 4340 (nickel-chromium-molybdenum) abbreviation: 4340 (UNS G43400) role: structural alloy category: metals type: steels-and-stainless summary: AISI 4340 (UNS G43400) is a nickel-chromium-molybdenum low-alloy steel. Its composition ranges are 0.38 to 0.43 percent carbon, 1.65 to 2.00 percent nickel, 0.70 to 0.90 percent chromium and 0.20 to 0.30 percent molybdenum (eFunda). Quenched and tempered to condition U (100 mm ruling section), its minimum yield strength is 740 MPa, and the supplier says it has higher tensile and yield strength than 4140 (voestalpine). best_for: Large sections that need high tensile strength and toughness after quenching and tempering, such as aircraft landing gear, gears and shafts (voestalpine, Saky Steel). weakest_at: 'Toughness at the highest strength levels: the minimum Charpy impact energy falls from 42 J at condition U to 9 J at condition Z (voestalpine). No corrosion data were read for this grade.' identity: formula: 'Fe balance; 0.38 to 0.43 C, 0.60 to 0.80 Mn, 0.15 to 0.30 Si, 0.70 to 0.90 Cr, 1.65 to 2.00 Ni, 0.20 to 0.30 Mo, 0.035 max P, 0.04 max S (wt%, composition ranges as printed by eFunda). The voestalpine datasheet prints single values under chemical analysis: C 0.43, Si 0.3, Mn 0.8, Ni 2.00, Cr 0.9, Mo 0.3, S 0.025, P 0.035.' source: efunda-4340 where: Composition table, Element and Weight % rows C to Mo (eFunda); the voestalpine chemical analysis row is printed in the formula text designations: - system: UNS code: G43400 source: voestalpine-4340 where: NEAREST STANDARDS table, UNS column - system: AISI code: '4340' source: voestalpine-4340 where: NEAREST STANDARDS table, AISI column - system: SAE code: '4340' source: wiki-4340-steel where: Reference list, title of SAE AMS6414M, printed (SAE 4340) - system: AMS code: '6414' source: efunda-4340 where: Designations, United States list, AMS 6414 - system: AMS code: 6414A source: efunda-4340 where: Designations, United States list, AMS 6414A - system: AMS code: '6415' source: efunda-4340 where: Designations, United States list, AMS 6415 - system: AMS code: 6415G source: efunda-4340 where: Designations, United States list, AMS 6415G - system: MIL code: MIL-S-16974 source: efunda-4340 where: Designations, United States list, MIL SPEC MIL-S-16974 - system: ASTM code: A322 source: efunda-4340 where: Designations, United States list, ASTM A322 - system: ASTM code: A331 source: efunda-4340 where: Designations, United States list, ASTM A331 - system: ASTM code: A505 source: efunda-4340 where: Designations, United States list, ASTM A505 - system: ASTM code: A519 source: efunda-4340 where: Designations, United States list, ASTM A519 - system: ASTM code: A547 source: efunda-4340 where: Designations, United States list, ASTM A547 - system: ASTM code: A646 source: efunda-4340 where: Designations, United States list, ASTM A646 - system: SAE code: J404 source: efunda-4340 where: Designations, United States list, SAE J404 - system: SAE code: J412 source: efunda-4340 where: Designations, United States list, SAE J412 - system: SAE code: J770 source: efunda-4340 where: Designations, United States list, SAE J770 - system: JIS code: SNCM 8 source: efunda-4340 where: 'Designations, Japan: JIS SNCM 8' - system: BS code: 817M40 source: efunda-4340 where: 'Designations, United Kingdom: B.S. 817 M 40' - system: BS code: EN24 note: nearest equivalent source: voestalpine-4340 where: NEAREST STANDARDS table, BS column - system: EN code: '1.6565' note: nearest equivalent source: voestalpine-4340 where: NEAREST STANDARDS table, DIN column, printed 1.6565 / 40NiCrMo6 - system: EN name code: 40NiCrMo6 note: nearest equivalent source: voestalpine-4340 where: NEAREST STANDARDS table, DIN column, printed 1.6565 / 40NiCrMo6 - system: EN code: '1.6582' note: nearest equivalent source: saky-4340-flatbar where: 'Product description: commonly known as 34CrNiMo6, 1.6582, or 817M40 in international standards' - system: EN name code: 34CrNiMo6 note: nearest equivalent source: saky-4340-flatbar where: 'Product description: commonly known as 34CrNiMo6, 1.6582, or 817M40 in international standards' tags: environments: [] stresses: [] applications: - structures - mechanisms properties: - benchmark: yield_strength label: Yield strength (Rp0.2 minimum), quenched and tempered, condition T value: 665 bound: lower unit: MPa scope: material conditions: condition: quenched and tempered to condition T section: limiting ruling section 150 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rp0.2, minimum unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column T, row Yield Strength (Rp 0.2 (Mpa)) - benchmark: ultimate_tensile_strength label: Tensile strength (Rm), quenched and tempered, condition T value: 850 unit: MPa scope: material conditions: condition: quenched and tempered to condition T section: limiting ruling section 150 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rm, range unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column T, row Tensile Rm (Mpa) value_high: 1000 bound: range - benchmark: elongation label: Elongation (A5) minimum, quenched and tempered, condition T value: 13 bound: lower unit: '%' scope: material conditions: condition: quenched and tempered to condition T section: limiting ruling section 150 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition gauge: A5 method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column T, row Elongation (A5 %) - benchmark: impact_energy label: Charpy impact energy (minimum), quenched and tempered, condition T value: 35 bound: lower unit: J scope: material conditions: condition: quenched and tempered to condition T section: limiting ruling section 150 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition test: Charpy impact test_temperature: not printed method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column T, row Charpy Impact (J) - benchmark: hardness_brinell label: Hardness (HB), quenched and tempered, condition T value: 248 unit: HB scope: material conditions: condition: quenched and tempered to condition T section: limiting ruling section 150 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition hardness_scale: HB method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column T, row Hardness (HB) value_high: 302 bound: range - benchmark: yield_strength label: Yield strength (Rp0.2 minimum), quenched and tempered, condition U value: 740 bound: lower unit: MPa scope: material conditions: condition: quenched and tempered to condition U section: limiting ruling section 100 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rp0.2, minimum unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column U, row Yield Strength (Rp 0.2 (Mpa)) - benchmark: ultimate_tensile_strength label: Tensile strength (Rm), quenched and tempered, condition U value: 930 unit: MPa scope: material conditions: condition: quenched and tempered to condition U section: limiting ruling section 100 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rm, range unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column U, row Tensile Rm (Mpa) value_high: 1080 bound: range - benchmark: elongation label: Elongation (A5) minimum, quenched and tempered, condition U value: 12 bound: lower unit: '%' scope: material conditions: condition: quenched and tempered to condition U section: limiting ruling section 100 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition gauge: A5 method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column U, row Elongation (A5 %) - benchmark: impact_energy label: Charpy impact energy (minimum), quenched and tempered, condition U value: 42 bound: lower unit: J scope: material conditions: condition: quenched and tempered to condition U section: limiting ruling section 100 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition test: Charpy impact test_temperature: not printed method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column U, row Charpy Impact (J) - benchmark: hardness_brinell label: Hardness (HB), quenched and tempered, condition U value: 269 unit: HB scope: material conditions: condition: quenched and tempered to condition U section: limiting ruling section 100 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition hardness_scale: HB method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column U, row Hardness (HB) value_high: 331 bound: range - benchmark: yield_strength label: Yield strength (Rp0.2 minimum), quenched and tempered, condition V value: 835 bound: lower unit: MPa scope: material conditions: condition: quenched and tempered to condition V section: limiting ruling section 63 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rp0.2, minimum unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column V, row Yield Strength (Rp 0.2 (Mpa)) - benchmark: ultimate_tensile_strength label: Tensile strength (Rm), quenched and tempered, condition V value: 1000 unit: MPa scope: material conditions: condition: quenched and tempered to condition V section: limiting ruling section 63 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rm, range unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column V, row Tensile Rm (Mpa) value_high: 1150 bound: range - benchmark: elongation label: Elongation (A5) minimum, quenched and tempered, condition V value: 12 bound: lower unit: '%' scope: material conditions: condition: quenched and tempered to condition V section: limiting ruling section 63 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition gauge: A5 method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column V, row Elongation (A5 %) - benchmark: impact_energy label: Charpy impact energy (minimum), quenched and tempered, condition V value: 42 bound: lower unit: J scope: material conditions: condition: quenched and tempered to condition V section: limiting ruling section 63 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition test: Charpy impact test_temperature: not printed method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column V, row Charpy Impact (J) - benchmark: hardness_brinell label: Hardness (HB), quenched and tempered, condition V value: 293 unit: HB scope: material conditions: condition: quenched and tempered to condition V section: limiting ruling section 63 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition hardness_scale: HB method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column V, row Hardness (HB) value_high: 352 bound: range - benchmark: yield_strength label: Yield strength (Rp0.2 minimum), quenched and tempered, condition W value: 925 bound: lower unit: MPa scope: material conditions: condition: quenched and tempered to condition W section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rp0.2, minimum unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column W, row Yield Strength (Rp 0.2 (Mpa)) - benchmark: ultimate_tensile_strength label: Tensile strength (Rm), quenched and tempered, condition W value: 1080 unit: MPa scope: material conditions: condition: quenched and tempered to condition W section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rm, range unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column W, row Tensile Rm (Mpa) value_high: 1230 bound: range - benchmark: elongation label: Elongation (A5) minimum, quenched and tempered, condition W value: 11 bound: lower unit: '%' scope: material conditions: condition: quenched and tempered to condition W section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition gauge: A5 method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column W, row Elongation (A5 %) - benchmark: impact_energy label: Charpy impact energy (minimum), quenched and tempered, condition W value: 35 bound: lower unit: J scope: material conditions: condition: quenched and tempered to condition W section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition test: Charpy impact test_temperature: not printed method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column W, row Charpy Impact (J) - benchmark: hardness_brinell label: Hardness (HB), quenched and tempered, condition W value: 311 unit: HB scope: material conditions: condition: quenched and tempered to condition W section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition hardness_scale: HB method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column W, row Hardness (HB) value_high: 375 bound: range - benchmark: yield_strength label: Yield strength (Rp0.2 minimum), quenched and tempered, condition X* value: 1005 bound: lower unit: MPa scope: material conditions: condition: 'quenched and tempered to condition X* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rp0.2, minimum unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column X*, row Yield Strength (Rp 0.2 (Mpa)) - benchmark: ultimate_tensile_strength label: Tensile strength (Rm), quenched and tempered, condition X* value: 1150 unit: MPa scope: material conditions: condition: 'quenched and tempered to condition X* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rm, range unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column X*, row Tensile Rm (Mpa) value_high: 1300 bound: range - benchmark: elongation label: Elongation (A5) minimum, quenched and tempered, condition X* value: 10 bound: lower unit: '%' scope: material conditions: condition: 'quenched and tempered to condition X* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition gauge: A5 method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column X*, row Elongation (A5 %) - benchmark: impact_energy label: Charpy impact energy (minimum), quenched and tempered, condition X* value: 28 bound: lower unit: J scope: material conditions: condition: 'quenched and tempered to condition X* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition test: Charpy impact test_temperature: not printed method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column X*, row Charpy Impact (J) - benchmark: hardness_brinell label: Hardness (HB), quenched and tempered, condition X* value: 341 unit: HB scope: material conditions: condition: 'quenched and tempered to condition X* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition hardness_scale: HB method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column X*, row Hardness (HB) value_high: 401 bound: range - benchmark: yield_strength label: Yield strength (Rp0.2 minimum), quenched and tempered, condition Y* value: 1080 bound: lower unit: MPa scope: material conditions: condition: 'quenched and tempered to condition Y* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rp0.2, minimum unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Y*, row Yield Strength (Rp 0.2 (Mpa)) - benchmark: ultimate_tensile_strength label: Tensile strength (Rm), quenched and tempered, condition Y* value: 1230 unit: MPa scope: material conditions: condition: 'quenched and tempered to condition Y* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rm, range unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Y*, row Tensile Rm (Mpa) value_high: 1380 bound: range - benchmark: elongation label: Elongation (A5) minimum, quenched and tempered, condition Y* value: 10 bound: lower unit: '%' scope: material conditions: condition: 'quenched and tempered to condition Y* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition gauge: A5 method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Y*, row Elongation (A5 %) - benchmark: impact_energy label: Charpy impact energy (minimum), quenched and tempered, condition Y* value: 20 bound: lower unit: J scope: material conditions: condition: 'quenched and tempered to condition Y* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition test: Charpy impact test_temperature: not printed method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Y*, row Charpy Impact (J) - benchmark: hardness_brinell label: Hardness (HB), quenched and tempered, condition Y* value: 363 unit: HB scope: material conditions: condition: 'quenched and tempered to condition Y* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition hardness_scale: HB method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Y*, row Hardness (HB) value_high: 429 bound: range - benchmark: yield_strength label: Yield strength (Rp0.2 minimum), quenched and tempered, condition Z* value: 1125 bound: lower unit: MPa scope: material conditions: condition: 'quenched and tempered to condition Z* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rp0.2, minimum unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Z*, row Yield Strength (Rp 0.2 (Mpa)) - benchmark: ultimate_tensile_strength label: Tensile strength (Rm), quenched and tempered, condition Z* value: 1550 unit: MPa scope: material conditions: condition: 'quenched and tempered to condition Z* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition strength_type: Rm, printed as greater than unit_in_source: Mpa method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Z*, row Tensile Rm (Mpa) bound: lower - benchmark: elongation label: Elongation (A5) minimum, quenched and tempered, condition Z* value: 5 bound: lower unit: '%' scope: material conditions: condition: 'quenched and tempered to condition Z* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition gauge: A5 method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Z*, row Elongation (A5 %) - benchmark: impact_energy label: Charpy impact energy (minimum), quenched and tempered, condition Z* value: 9 bound: lower unit: J scope: material conditions: condition: 'quenched and tempered to condition Z* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition test: Charpy impact test_temperature: not printed method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Z*, row Charpy Impact (J) - benchmark: hardness_brinell label: Hardness (HB), quenched and tempered, condition Z* value: 444 unit: HB scope: material conditions: condition: 'quenched and tempered to condition Z* (asterisked: typically ordered annealed for machining, then heat treated)' section: limiting ruling section 30 mm heat_treatment: harden 815 to 845 C, oil or polymer quench; temper 455 to 650 C for at least 2 h, air cool (recommended ranges) tempering: 455 to 650 C recommended range; the datasheet gives one range for the whole process, not one tempering temperature per condition hardness_scale: HB method: Heat-treated mechanical properties table, value printed in this column; datasheet minimums and ranges kept as printed status: ground source: voestalpine-4340 where: Mechanical Properties (heat treated) table, column Z*, row Hardness (HB) bound: lower - benchmark: density label: Density at 25 C (printed as x1000 kg/m3) value: 7.7 value_high: 8.03 bound: range unit: g/cm3 scope: material conditions: temperature: 25 C unit_in_source: x1000 kg/m3 method: eFunda Mechanical Properties table, range as printed; 1 g/cm3 equals 1000 kg/m3, so the printed numbers are kept and the unit is written as g/cm3 status: ground source: efunda-4340 where: Mechanical Properties table, Density row, 7.7 - 8.03 at 25 C - benchmark: poissons_ratio label: Poisson's ratio at 25 C value: 0.27 value_high: 0.3 bound: range unit: '-' scope: material conditions: temperature: 25 C method: eFunda Mechanical Properties table, range as printed status: ground source: efunda-4340 where: Mechanical Properties table, Poisson's Ratio row, 0.27-0.30 at 25 C - benchmark: elastic_modulus label: Elastic modulus at 25 C value: 190 value_high: 210 bound: range unit: GPa scope: material conditions: temperature: 25 C method: eFunda Mechanical Properties table, range as printed status: ground source: efunda-4340 where: Mechanical Properties table, Elastic Modulus row, 190 - 210 at 25 C - benchmark: ultimate_tensile_strength label: Tensile strength, annealed at 810 C, 25 C value: 744.6 unit: MPa scope: material conditions: temperature: 25 C treatment: annealed at 810 C (as printed by eFunda) method: eFunda Mechanical Properties table, single value on the row; the page offers more conditions behind a link, and those were not read status: ground source: efunda-4340 where: Mechanical Properties table, Tensile Strength row, 744.6 MPa at 25 C, annealed at 810 C - benchmark: hardness_brinell label: Hardness, annealed at 810 C, 25 C value: 217 unit: HB scope: material conditions: temperature: 25 C treatment: annealed at 810 C (as printed by eFunda) hardness_scale: HB method: eFunda Mechanical Properties table, single value on the row status: ground source: efunda-4340 where: Mechanical Properties table, Hardness (HB) row, 217 at 25 C, annealed at 810 C - benchmark: impact_energy label: Izod impact energy, annealed at 810 C, 25 C value: 51.1 unit: J scope: material conditions: test: Izod temperature: 25 C treatment: annealed at 810 C (as printed by eFunda) method: eFunda Mechanical Properties table, Impact Strength (Izod) row, single value status: ground source: efunda-4340 where: Mechanical Properties table, Impact Strength (J) (Izod) row, 51.1 at 25 C, annealed at 810 C - benchmark: cte label: Coefficient of thermal expansion, 20 to 100 C, oil hardened and tempered 630 C value: 11.5 unit: ppm/K scope: material conditions: temperature: 20 to 100 C treatment: oil hardened, tempered 630 C (as printed by eFunda) unit_in_source: 10^-6/degC method: eFunda Thermal Properties table, Thermal Expansion row; 10^-6 per degC is numerically the same as ppm/K status: ground source: efunda-4340 where: Thermal Properties table, Thermal Expansion row, 11.5 at 20 to 100 C, oil hardened tempered 630 C - benchmark: hardness_rockwell_c label: Hardness, quenched and tempered bars (typical range) value: 24 value_high: 38 bound: range unit: HRC scope: material conditions: condition: quenched and tempered bars, typical range as the text states temper: not stated test: Rockwell or Brinell, as the text states method: 'Product page text: typical range stated for quenched and tempered bars (a sentence, not a table value)' status: ground source: saky-4340-flatbar where: Text under the heading 4340 Bar Hardness Test, sentence beginning For quenched and tempered bars corrosion: [] risks: hazards: - text: 'PubChem aggregated GHS for elemental nickel (signal word Danger) from 4,778 company reports: H317 (99.9%), H372 (99.7%), H351 (72.9%), H412 (47.2%), H350 (22.5%), H360F (18%), H341 (13.5%) and H334 (10.3%) are the reported codes. 0.1% (5 of 4,778) of reports say it does not meet GHS criteria. The data cover the element, not this alloy.' ghs: - H317 - H372 - H351 - H412 - H350 - H360F - H341 - H334 source: pubchem-nickel where: Safety and Hazards, GHS Classification, aggregated notifications (CID 935) - text: 'PubChem aggregated GHS for elemental chromium (signal word Danger) from 2,404 reports: H317 (20.7%), H334 (20.3%) and H319 (19.1%) are the reported codes. 50% (1,202 of 2,404) of reports say it does not meet GHS criteria. The data cover the element, not this alloy.' ghs: - H317 - H334 - H319 source: pubchem-chromium where: Safety and Hazards, GHS Classification (CID 23976) - text: 'PubChem GHS for elemental molybdenum (signal word Danger) from 1,523 reports: H228 (30%), H361 (29.5%) and H225 (11.6%) are the reported codes. 57.4% (874 of 1,523) of reports say it does not meet GHS criteria. H225 (highly flammable liquid) does not fit a metal and is shown as printed. The data cover the element, not this alloy.' ghs: - H228 - H361 - H225 source: pubchem-molybdenum where: Safety and Hazards, GHS Classification (CID 23932) failure_risks: - mode: Loss of toughness at the highest strength level trigger: Quenched and tempered to condition Z (limiting ruling section 30 mm), minimum yield strength 1125 MPa consequence: Minimum Charpy impact energy 9 J and minimum elongation 5 % (A5), with hardness above 444 HB, against minimum 42 J and 12 % at condition U (ruling section 100 mm). The datasheet gives minimums, not typical values. severity: moderate source: voestalpine-4340 where: Mechanical Properties (heat treated) table, columns U and Z* side_effects: [] handling: - text: 'Recommended heat treatment: normalise at 870 to 920 C for 10 to 20 minutes per 25 mm and air cool; anneal at 830 to 860 C and furnace cool; harden at 815 to 845 C for 10 to 20 minutes per 25 mm with an oil or polymer quench; temper at 455 to 650 C for at least 2 hours, then air cool.' source: voestalpine-4340 where: Heat Treatment (recommended) rows - text: Stress relieve 30 to 50 C below the last tempering temperature after quench and temper; in the annealed condition stress relieve at 650 to 675 C. source: voestalpine-4340 where: Stress Relieve rows - text: 'Supply condition: quenched and tempered to condition U and V, with surfaces black, peeled and polished, or rough machined. Asterisked conditions X, Y and Z are typically ordered annealed for machining and heat treated afterwards.' source: voestalpine-4340 where: Supply condition table and footnote - text: 'Hardness check: for quenched and tempered bars the typical hardness is 24 to 38 HRC, measured by Rockwell or Brinell testing.' source: saky-4340-flatbar where: Text, 4340 Bar Hardness Test mitigations: - text: The datasheet says the addition of molybdenum prevents the steel from being susceptible to temper brittleness. source: voestalpine-4340 where: Description - text: 'Use the lower strength conditions where toughness counts most: the minimum Charpy impact energy is 42 J at condition U and 9 J at condition Z.' source: voestalpine-4340 where: Charpy Impact row, columns U and Z* uses: - application: structures device: Aircraft landing gear assemblies, including struts and linkages example: Saky Steel lists aircraft landing gear assemblies, with struts and linkages, as an application of AISI 4340 flat bar. source: saky-4340-flatbar where: Applications list, item 1 - application: mechanisms device: Gears, shafts and crankshafts example: Saky Steel lists automotive drivetrain gears and shafts, high-performance engine crankshafts, and heavy-duty gears and shafts for power transmission. source: saky-4340-flatbar where: Applications list, items 2, 4 and 5 - application: mechanisms device: Forged hydraulic pistons, cylinders and fittings example: Saky Steel lists forged hydraulic system parts such as pistons, cylinders and fittings. source: saky-4340-flatbar where: Applications list, item 3 supply: - subject: Chromium abundance: World resources are greater than 12 billion tons of shipping-grade chromite, and 95 percent of world chromium resources are in Kazakhstan and southern Africa. US net import reliance was 79 percent of apparent consumption in 2025 (estimated). producers: - country: South Africa share_percent: 45.1 year: 2025 - country: Turkey share_percent: 17.6 year: 2025 - country: Kazakhstan share_percent: 13.7 year: 2025 - country: India share_percent: 5.9 year: 2025 - country: Brazil share_percent: 3.9 year: 2025 - country: Zimbabwe share_percent: 3.9 year: 2025 critical_lists: - list: USGS Final 2025 Critical Minerals List (MCS 2026 introduction, Table 6) listed: true recycling: Recycled chromium in reported stainless-steel scrap receipts was 21 percent of US apparent consumption in 2025. substitutes: - Chromium has no substitute in stainless steel, the leading end use, or in superalloys (USGS 2026). source: usgs-chromium-2026 where: Salient Statistics; World Mine Production and Reserves, 2025e (shares calculated as printed tonnage over the 51,000 thousand t world total); World Resources; Substitutes; Recycling - subject: Molybdenum abundance: World reserves were 17,000 thousand t (USGS table). Identified resources are about 5.4 million tons in the United States and about 20 million tons in the rest of the world. Molybdenum is used principally as an alloying agent in cast iron, steel and superalloys. The Government of China imposed export controls on molybdenum powders in February 2025. producers: - country: China share_percent: 37.3 year: 2025 - country: Chile share_percent: 16.2 year: 2025 - country: United States share_percent: 15.4 year: 2025 - country: Peru share_percent: 15 year: 2025 - country: Mexico share_percent: 6.5 year: 2025 critical_lists: - list: USGS Final 2025 Critical Minerals List (MCS 2026 introduction, Table 6) listed: false recycling: Molybdenum is recycled in catalysts, ferrous scrap and superalloy scrap; USGS says recycled molybdenum may be as much as 30 percent of apparent supply. substitutes: - 'USGS: there is little substitution for molybdenum in steels and cast irons; potential substitutes in alloy steels include boron, chromium, niobium (columbium) and vanadium.' source: usgs-molybdenum-2026 where: Domestic Production and Use; World Mine Production and Reserves, 2025e (shares calculated over the 260,000 t world total); World Resources; Substitutes; Recycling - subject: Nickel abundance: Globally, nickel resources are estimated at more than 350 million tons, and the world reserve total is more than 140 million tons (USGS). In the United States, stainless and alloy steel and nickel-containing alloys typically account for more than 85 percent of domestic consumption. producers: - country: Indonesia share_percent: 66.7 year: 2025 - country: Philippines share_percent: 6.9 year: 2025 - country: Russia share_percent: 5.1 year: 2025 - country: Canada share_percent: 3.6 year: 2025 - country: New Caledonia share_percent: 3.6 year: 2025 critical_lists: - list: USGS Final 2025 Critical Minerals List (MCS 2026 introduction, Table 6) listed: true recycling: Nickel recovered from scrap accounted for about 60 percent of US apparent consumption in 2025 (estimated). substitutes: - 'USGS: low-nickel, duplex or ultrahigh-chromium stainless steels have been substituted for austenitic grades in construction; nickel-free specialty steels are sometimes used in place of stainless steel in power generation and petrochemical industries.' source: usgs-nickel-2026 where: Salient Statistics; World Mine Production and Reserves, 2025e (shares calculated over the 3,900,000 t world total); World Resources; Substitutes; Recycling media: [] documents: - title: 'voestalpine High Performance Metals: AISI 4340 / 1.6565 / G43400 datasheet (Australia)' type: datasheet url: https://www.voestalpine.com/highperformancemetals/australia/app/uploads/sites/265/2024/08/Datasheet-4340-2026-v1.pdf - title: 'eFunda: Properties of Alloy Steels, AISI 4340 (designations, composition, properties)' type: database url: https://www.efunda.com/materials/alloys/alloy_steels/show_alloy.cfm?id=aisi_4340&prop=all - title: 'Saky Steel: AISI 4340 Alloy Steel Flat Bar (stockist page)' type: datasheet url: https://www.sakysteel.com/aisi-4340-alloy-steel-flat-bar-high-strength-low-alloy-steel-supplier.html - title: 'Wikipedia: 4340 steel (equivalent-grade table and AMS reference list only)' type: database url: https://en.wikipedia.org/wiki/4340_steel - title: 'USGS Mineral Commodity Summaries 2026: Chromium' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf year: 2026 - title: 'USGS Mineral Commodity Summaries 2026: Molybdenum' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf year: 2026 - title: 'USGS Mineral Commodity Summaries 2026: Nickel' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf year: 2026 - title: 'USGS Mineral Commodity Summaries 2026, Introduction: Table 6, Final 2025 Critical Minerals List' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026.pdf year: 2026 - title: 'PubChem: Nickel (CID 935), GHS classification' type: database url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/935/JSON/?heading=GHS+Classification year: 2026 - title: 'PubChem: Chromium (CID 23976), GHS classification' type: database url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON/?heading=GHS+Classification year: 2026 - title: 'PubChem: Molybdenum (CID 23932), GHS classification' type: database url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23932/JSON/?heading=GHS+Classification year: 2026 gaps: - No normalised mechanical properties were found. The voestalpine datasheet gives only the recommended normalising range (870 to 920 C), and no other source read in this run gives a normalised strength. - 'Annealed values come only from eFunda: tensile strength 744.6 MPa, hardness 217 HB and Izod impact 51.1 J at 25 C, annealed at 810 C. The voestalpine datasheet recommends annealing at 830 to 860 C, so both annealing temperatures are kept as printed.' - eFunda prints yield strength 472.3 MPa, elongation 22.0 % and reduction in area 49.9 % with no temperature or heat treatment, so these values are not recorded. - The quenched and tempered rows use the voestalpine ruling-section conditions and the recommended temper range 455 to 650 C. Only eFunda gives a specific temper (oil hardened, tempered 630 C), and that is recorded on its thermal expansion row only. - The Saky Steel product table prints tensile 850 to 1000 MPa, yield 680 to 860 MPa, elongation 14 % and hardness 24 to 28 HRC with no heat-treatment condition, so these values are not recorded. - The eFunda electrical resistivity row (248, unit printed as 10^-9 with a symbol-font character) is left out because the unit could not be confirmed from the text. - 'Corrosion: no corrosion test or service data for AISI 4340 were found in the sources read in this run. The 2021 ITATS paper covers AISI 1045, AISI 4140 and SS 304 only, and the datasheets give no corrosion statement, so the corrosion list is empty.' - Fracture toughness, fatigue, hydrogen embrittlement and notch values for AISI 4340 were not found in the sources read in this run. The Sandia hydrogen-compatibility reference (code 1211) has no AISI 4340 entry (checked in this run). - 'Launch-vehicle use: no source read in this run prints one for AISI 4340. The aerospace uses recorded are aircraft landing gear (Saky Steel) and the AMS specification numbers listed by eFunda.' - 'Designations left out: AMS 5331, AMS 6359 and AMS 6359B (listed by eFunda for AISI 4340), because no spec page was read to confirm their scope. AFNOR 35NCD6, JIS SNCM447, 35CrNiMo6, 40CrNiMo, 40KHN2MA and 36CrNiMo6 (in the Wikipedia equivalent-grade row) are also left out, because no standards page in this run confirms them.' - The Wikipedia AMS reference list names AMS6414M as Vacuum Consumable Electrode Remelted with UNS G43406. G43406 is a different UNS code and is not used here. The AMS 6414 and AMS 6415 spec documents were not read, so their product forms and melting practice are not confirmed. - The JIS designation SNCM 8 is printed by eFunda for AISI 4340, but no JIS standard page was read to confirm it. - 'Nearest-equivalent entries: DIN 1.6565, EN name 40NiCrMo6 and BS EN24 come from the voestalpine NEAREST STANDARDS table; 34CrNiMo6 and 1.6582 come from Saky Steel, which says the grade is commonly known as them. All five carry the note nearest equivalent.' - 'Composition: eFunda and Saky Steel print ranges (Saky Steel has no phosphorus or sulfur row). voestalpine prints single values under chemical analysis and does not label them as maxima. The recipe uses the eFunda ranges.' - Shares of world production are calculated from the USGS tonnage tables (2025e) over the printed world totals, because the USGS tables do not print shares. - 'Critical list: read from Table 6 of the Mineral Commodity Summaries 2026 introduction (PDF). Molybdenum is not in Table 6 and is recorded as not listed. The USGS web page for the list returned HTTP 403, and the EU critical raw materials list was not read.' - Hazards are PubChem records for the elements nickel, chromium and molybdenum, not for the alloy. No safety data sheet for AISI 4340 bar was read. PubChem molybdenum record lists H225 (highly flammable), which does not fit a metal; it is shown as printed. Welding and grinding fume hazards of the steel itself are not sourced. - The failure-risk severity rating is an assistant judgement, not a value from a source. - 'Benchmarks not in property-canon.yaml, used as snake_case names: impact_energy, hardness_brinell and hardness_rockwell_c.' - Density is printed in x1000 kg/m3 by eFunda; the value is written as g/cm3 with the printed unit kept in conditions.unit_in_source (1 g/cm3 equals 1000 kg/m3). - The Saky Steel page is a stockist page. Its applications list is the supplier statement, not a standard. - The Elgin 4340 fact sheet and the aircraftmaterials.com 4340 page could not be fetched in this run (not found), so they are not cited. No image was added to media. sources: voestalpine-4340: title: 'voestalpine High Performance Metals: AISI 4340 / 1.6565 / G43400 datasheet' id: AISI 4340 / 1.6565 / G43400 url: https://www.voestalpine.com/highperformancemetals/australia/app/uploads/sites/265/2024/08/Datasheet-4340-2026-v1.pdf kind: datasheet license: supplier datasheet, cited not reproduced efunda-4340: title: 'eFunda: Properties of Alloy Steels, AISI 4340' id: eFunda AISI 4340 page url: https://www.efunda.com/materials/alloys/alloy_steels/show_alloy.cfm?id=aisi_4340&prop=all kind: database license: eFunda website, cited not reproduced saky-4340-flatbar: title: 'Saky Steel: AISI 4340 Alloy Steel Flat Bar (stockist page)' id: AISI 4340 alloy steel flat bar url: https://www.sakysteel.com/aisi-4340-alloy-steel-flat-bar-high-strength-low-alloy-steel-supplier.html kind: datasheet license: supplier web page, cited not reproduced wiki-4340-steel: title: 'Wikipedia: 4340 steel' id: 4340 steel (equivalent-grade table and AMS reference list used) url: https://en.wikipedia.org/wiki/4340_steel kind: web license: CC BY-SA 4.0 usgs-chromium-2026: title: 'USGS Mineral Commodity Summaries 2026: Chromium' id: mcs2026-chromium url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf year: 2026 kind: report license: public domain (USGS) usgs-molybdenum-2026: title: 'USGS Mineral Commodity Summaries 2026: Molybdenum' id: mcs2026-molybdenum url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf year: 2026 kind: report license: public domain (USGS) usgs-nickel-2026: title: 'USGS Mineral Commodity Summaries 2026: Nickel' id: mcs2026-nickel url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf year: 2026 kind: report license: public domain (USGS) usgs-critical-2026: title: 'USGS Mineral Commodity Summaries 2026, Introduction: Table 6, Final 2025 Critical Minerals List' id: mcs2026 introduction, Table 6 url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026.pdf year: 2026 kind: report license: public domain (USGS) pubchem-nickel: title: 'PubChem: Nickel (CID 935), Safety and Hazards, GHS Classification' id: CID 935 url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/935/JSON/?heading=GHS+Classification year: 2026 kind: database license: PubChem terms (public) pubchem-chromium: title: 'PubChem: Chromium (CID 23976), Safety and Hazards, GHS Classification' id: CID 23976 url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON/?heading=GHS+Classification year: 2026 kind: database license: PubChem terms (public) pubchem-molybdenum: title: 'PubChem: Molybdenum (CID 23932), Safety and Hazards, GHS Classification' id: CID 23932 url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23932/JSON/?heading=GHS+Classification year: 2026 kind: database license: PubChem terms (public) license: CC-BY-4.0 updated: '2026-10-24' review: status: draft method: assistant checked_values: 43 unreachable: 5 caveats: 4 note: 'Read by an AI assistant on 2026-10-24 from pages fetched in this run: voestalpine AISI 4340 datasheet, eFunda AISI 4340, Saky Steel 4340 flat bar, Wikipedia 4340 steel, USGS MCS 2026 chromium, molybdenum, nickel and introduction, PubChem nickel, chromium and molybdenum. Unreachable: aircraftmaterials.com 4340 page (404), Elgin 4340 fact sheet (no such key), ASM Aerospace Specification Metals page (not found), steel-bar.com (138-byte response), USGS critical-list web page (403). Web search was unavailable in this run.' story: recipe: line: AISI 4340 is an iron-based nickel-chromium-molybdenum steel. The composition ranges printed by eFunda are 0.38 to 0.43 percent carbon, 0.60 to 0.80 manganese, 0.15 to 0.30 silicon, 0.70 to 0.90 chromium, 1.65 to 2.00 nickel and 0.20 to 0.30 molybdenum, with phosphorus at 0.035 maximum, sulfur at 0.04 maximum and iron as the balance. Its strength comes from heat treatment (normalise, anneal, harden and temper) as much as from its composition. parts: - name: Iron symbol: Fe share_note: balance (the rest) role: The matrix of the steel. Heat treatment changes its structure from austenite to martensite and then tempered martensite. source: efunda-4340 where: Composition table - name: Carbon symbol: C share_percent: 0.38 share_high: 0.43 role: Sets how hard the steel can become when quenched. source: efunda-4340 where: Composition table, C row - name: Manganese symbol: Mn share_percent: 0.6 share_high: 0.8 role: Deoxidiser and hardenability aid in the melt. source: efunda-4340 where: Composition table, Mn row - name: Silicon symbol: Si share_percent: 0.15 share_high: 0.3 role: Deoxidiser in the melt. source: efunda-4340 where: Composition table, Si row - name: Chromium symbol: Cr share_percent: 0.7 share_high: 0.9 role: Adds hardenability and wear resistance. The grade is a low-alloy steel, not a stainless steel. source: efunda-4340 where: Composition table, Cr row - name: Nickel symbol: Ni share_percent: 1.65 share_high: 2 role: Adds strength and toughness. voestalpine describes the grade as a nickel, chromium, molybdenum steel. source: efunda-4340 where: Composition table, Ni row - name: Molybdenum symbol: Mo share_percent: 0.2 share_high: 0.3 role: Adds hardenability. The datasheet says it prevents temper brittleness. source: efunda-4340 where: Composition table, Mo row - name: Phosphorus symbol: P share_percent: null share_high: 0.035 share_note: maximum role: Impurity held low. source: efunda-4340 where: Composition table, P row - name: Sulfur symbol: S share_percent: null share_high: 0.04 share_note: maximum role: Impurity held low. source: efunda-4340 where: Composition table, S row risk_groups: - title: For people level: 1 verdict: Element records show sensitizer and cancer codes lead: No safety data sheet for AISI 4340 bar was read. The PubChem records below are for nickel, chromium and molybdenum as elements. points: - label: Nickel line: PubChem's aggregated record lists H317 (99.9%, allergic skin reaction), H351 (72.9%, suspected of causing cancer) and H372 (99.7%, organ damage from repeated exposure). - label: Chromium line: PubChem lists H317 (20.7%), H334 (20.3%) and H319 (19.1%). 50% (1,202 of 2,404) of reports say it does not meet GHS criteria. - label: Molybdenum line: PubChem lists H361 (29.5%, suspected of damaging fertility or the unborn child) and H228 (30%, flammable solid). 57.4% (874 of 1,523) of reports say it does not meet GHS criteria. - title: Heat treatment level: 1 verdict: Toughness falls as strength rises lead: Strength comes from heat treatment, and the minimum toughness falls at the highest strength level. points: - label: Highest strength level line: At condition Z the minimum Charpy impact energy is 9 J and the minimum elongation is 5 percent, with hardness above 444 HB (voestalpine). - label: Tempering range line: The datasheet recommends tempering at 455 to 650 C for at least 2 hours and does not give one tempering temperature for each condition. why: AISI 4340 (UNS G43400) is a nickel-chromium-molybdenum steel for parts that must carry high tensile strength and toughness, particularly in large cross sections in the quenched and tempered condition (voestalpine). Its supplier says it has higher tensile and yield strength than 4140. Its strength depends on heat treatment, so every value in this profile carries its own condition. uses: - where: Aircraft landing gear line: Saky Steel says AISI 4340 flat bar is widely used for aircraft landing gear assemblies, including struts and linkages. - where: Gears, shafts and crankshafts line: The same supplier lists automotive drivetrain gears and shafts, high-performance engine crankshafts and heavy-duty gears and shafts for power transmission. - where: Forged hydraulic parts line: Forged hydraulic pistons, cylinders and fittings, which the supplier names as a use of the alloy. can_do: - label: Strength line: Quenched and tempered to condition U (100 mm ruling section), the minimum yield strength is 740 MPa and the tensile strength is 930 to 1080 MPa (voestalpine). - label: Toughness line: In the same condition the minimum Charpy impact energy is 42 J (voestalpine). - label: Annealed line: Annealed at 810 C and tested at 25 C, eFunda gives a tensile strength of 744.6 MPa and a hardness of 217 HB. - label: Stiffness and density line: At 25 C, eFunda gives an elastic modulus of 190 to 210 GPa and a density of 7.7 to 8.03 g/cm3 (printed as x1000 kg/m3). - label: Hardness line: For quenched and tempered bars the typical hardness is 24 to 38 HRC (Saky Steel). compare: The supplier describes AISI 4340 as a nickel, chromium and molybdenum steel with higher tensile and yield strength than 4140 (voestalpine). Its nickel content is 1.65 to 2.00 percent (eFunda). No 4140 values were read in this run, so this profile gives no numbers for the comparison. compare_rows: - label: Strength, quenched and tempered benchmark: yield_strength - label: Stiffness benchmark: elastic_modulus - label: Density benchmark: density handling: - Quote the heat-treatment condition with every strength value; the datasheet gives a separate row for each ruling-section condition. - Harden at 815 to 845 C with an oil or polymer quench, then temper at 455 to 650 C for at least 2 hours (recommended ranges). - Stress relieve 30 to 50 C below the last tempering temperature after quench and temper (voestalpine). - No safety data sheet for AISI 4340 bar was read in this run; take the supplier sheet for the bar you cut, grind or weld. good_for: - Large sections in the quenched and tempered condition that need high tensile strength and toughness (voestalpine). - Aircraft landing gear struts and linkages, and gears and shafts, which the stockist lists as main uses (Saky Steel). watch_out: - 'Toughness falls as strength rises: the minimum Charpy impact energy is 42 J at condition U (yield 740 MPa) and 9 J at condition Z (yield 1125 MPa).' - The tempering temperature for each condition is not printed; the recommended range is 455 to 650 C. - 'The annealing temperature differs between sources: eFunda gives 810 C and voestalpine gives 830 to 860 C.' - No corrosion data for AISI 4340 were read in this run. verdict: AISI 4340 is a strong, tough nickel-chromium-molybdenum steel for large heat-treated sections, and its supplier names aircraft landing gear among its uses. Its values change with the ruling section and the temper, so quote the condition with each one. The figures are supplier minimums, and no corrosion or hydrogen data were read in this run.