Carbon and alloy steels

carbon-and-alloy-steels

9 materials across 1 types

About carbon and alloy steels

Carbon and alloy steels (A36, 1018, 1215, 4140): strength by condition, composition and corrosion data with sources.

Carbon steels get their properties from carbon content and processing; alloy steels add elements such as chromium and molybdenum for hardenability and strength. Cold-drawn, hot-rolled, normalised and quenched-and-tempered material differ widely, so each value names how the material was processed.

At a glance

Highest yield strength: Alloy steel AISI 4130 reaches 1,330 MPa. Lowest: Carbon steel 1010 starts at 170 MPa. (9 of 9 grades have a sourced value.)
Highest tensile strength: Alloy steel AISI 4130 reaches 1,600 MPa. Lowest: Carbon steel 1010 starts at 310 MPa. (9 of 9 grades have a sourced value.)
Highest density: Carbon steel 1070 reaches 8.03 g/cm³. Lowest: Carbon steel 1018 starts at 7.67 g/cm³. (8 of 9 grades have a sourced value.)

Ranges run across the conditions each source reports (temper, heat treatment, form), measured at room temperature where the source says so.

How they compare

The same measurements for every material in the collection. A range means the grade has values under several conditions; "at least" means the source gives a specified minimum. "no data" means no sourced value yet. For ranked tables, open a benchmark.

Carbon and alloy steels: how the grades compare
Material	Yield strength	Tensile strength	Density	Young's modulus	Thermal conductivity	Melting point
A36 structural carbon steelstructural steel	at least 220 MPa	400 to 552 MPa	7.8 g/cm³	200 GPa	no data	no data
Carbon steel 1018low-carbon structural steel	240 to 370 MPa	430 to 440 MPa	7.67 to 7.9 g/cm³	190 to 210 GPa	25 to 93 W/(m·K)	1,480 to 1,526 °C
Carbon steel 1045medium-carbon machinery steel	300 to 540 MPa	552 to 700 MPa	no data	190 to 210 GPa	no data	no data
Carbon steel 1215free-machining carbon steel	415 MPa	540 MPa	7.67 to 7.87 g/cm³	190 to 210 GPa	51.9 W/(m·K)	no data
Alloy steel AISI 4130structural alloy	435 to 1,330 MPa	655 to 1,600 MPa	7.85 g/cm³	205 GPa	30.1 to 42.7 W/(m·K)	1,432 °C
Alloy steel AISI 4140structural alloy	570 to 1,235 MPa	745 to 1,283 MPa	7.85 g/cm³	205 GPa	42.6 W/(m·K)	no data
Carbon steel 1010plain low-carbon steel	170 to 345 MPa	310 to 450 MPa	7.9 g/cm³	190 to 210 GPa	64.2 W/(m∙°C)	no data
Carbon steel 1070high-carbon spring steel	390 to 495 MPa	640 to 700 MPa	7.7 to 8.03 g/cm³	190 to 210 GPa	50 W/(m·K)	no data
Alloy steel AISI 4340structural alloy	at least 665 MPa	745 to 1,550 MPa	7.7 to 8.03 g/cm³	190 to 210 GPa	no data	no data

What these materials are made of

Composition by weight, as printed in the sources for each grade (the first constituents listed).

Composition of each grade
Material	Main constituents
A36 structural carbon steel	Fe balance · C up to 0.26% · Si up to 0.4% · Mn up to 1.03% · P up to 0.04% · S up to 0.05% · Cu up to 0.2%
Carbon steel 1018	Fe balance · C 0.14 to 0.2% · Mn 0.6 to 0.9% · P up to 0.040% · S up to 0.050%
Carbon steel 1045	Fe balance · C 0.43 to 0.5% · Mn 0.6 to 0.9% · P up to 0.040% · S up to 0.050% · Si up to 0.100%
Carbon steel 1215	Fe balance · C up to 0.090% · Mn 0.75 to 1.05% · P 0.04 to 0.09% · S 0.26 to 0.35%
Alloy steel AISI 4130	Fe balance · C 0.28 to 0.33% · Mn 0.4 to 0.6% · Si 0.15 to 0.35% · Cr 0.8 to 1.1% · Mo 0.15 to 0.25% · P up to 0.035%
Alloy steel AISI 4140	Fe balance · C 0.38 to 0.43% · Mn 0.75 to 1% · Si 0.15 to 0.35% · Cr 0.8 to 1.1% · Mo 0.15 to 0.25% · P up to 0.035%
Carbon steel 1010	Fe balance · C 0.08 to 0.13% · Mn 0.3 to 0.6% · P up to 0.04% · S up to 0.05%
Carbon steel 1070	Fe balance · C 0.65 to 0.75% · Mn 0.6 to 0.9%
Alloy steel AISI 4340	Fe balance · C 0.38 to 0.43% · Mn 0.6 to 0.8% · Si 0.15 to 0.3% · Cr 0.7 to 0.9% · Ni 1.65 to 2% · Mo 0.2 to 0.3%

Where they are used

Uses
Use	Grades
General construction and structural framing	A36 structural carbon steel
Girders, structural shapes and angle iron	A36 structural carbon steel
Bolted and welded structural joints	A36 structural carbon steel
Shafts, pins and gears	Carbon steel 1018
Low-stress structural components	Carbon steel 1018
Car parts, pipes and construction steel	Carbon steel 1018
Axles, clutch members and shafts	Carbon steel 1045
Gears, pinions and stud bolts	Carbon steel 1045
Heavy machinery parts	Carbon steel 1045
Bushings, inserts, pins and couplings	Carbon steel 1215
Studs	Carbon steel 1215
Valve and pump parts, general engineering and automotive parts	Carbon steel 1215
Solid rocket booster case	Alloy steel AISI 4130
Aircraft tube, sheet and bar for military and commercial aircraft	Alloy steel AISI 4130
Oil and gas wellhead and Christmas tree parts	Alloy steel AISI 4130
Axles, gears, shafts, spindles, pinions, sprockets and studs	Alloy steel AISI 4140

When each grade fits

Best use and weak spots of each grade
Material	Best for	Weakest at
A36 structural carbon steel	Welded and bolted structural frames, girders and shapes that will be painted or galvanized	Rusts outdoors and corrodes first when it touches copper or tin in a wet electrolyte; minimum strength falls above 650 °F (343 °C)
Carbon steel 1018	Machined shafts, pins and gears, and cost-sensitive structural parts that are coated against rust	Rust in moist air and salt unless it is coated, and strength that depends on whether the bar was cold drawn or hot rolled
Carbon steel 1045	Forged or machined axles, shafts, gears and machine parts that need more strength than low-carbon steel, and that are coated against rust	Rust in moist air and salt unless it is coated, and strength that depends on whether the bar was cold drawn, hot rolled, normalised or annealed
Carbon steel 1215	Screw-machine parts such as bushings, inserts, pins, studs and couplings, where machining speed and surface finish matter more than weldability (Alro; Titanium Industries)	Welding and fatigue. Alro says it is difficult to weld, and Titanium Industries says it fails in parts under severe fatigue stress
Alloy steel AISI 4130	Aircraft and motorsport tube, sheet and bar, and oil and gas parts, where weldability and strength after heat treatment both matter	Hydrogen gas and salt solutions: in one laboratory study the threshold stress intensity fell from 88 to 32 MPa√m as hydrogen pressure rose from 21 to 69 MPa, and salt solution cut corrosion-fatigue life
Alloy steel AISI 4140	Machine parts and structures in medium and large sections that need high strength and toughness after quenching and tempering	Hydrogen gas, which cut notched strength by about 60 percent in one room-temperature study, and dilute sulfuric acid, which corroded it at 176.87 mpy
Carbon steel 1010	Formed, drawn and welded parts, and light structural parts, where cost and ductility matter	Rust in moist air and salt unless it is coated, and strength that depends on the processing condition
Carbon steel 1070	Springs, shafts and hand tools that are heat treated and kept dry or coated (tensile strength 640 to 700 MPa in the supplier range)	Corrosion, which is poor without a coating, brittleness once fully hardened, and poor weldability
Alloy steel AISI 4340	Large sections that need high tensile strength and toughness after quenching and tempering, such as aircraft landing gear, gears and shafts (voestalpine, Saky Steel).	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.