Guides/Comparisons
Stainless steel vs carbon steel
stainless-steel-vs-carbon-steelStainless steel and Carbon and alloy steel at a glance
This page compares Stainless steel and Carbon and alloy steel using only values that carry a source, a test condition and an evidence level. Ranges run across temper, heat treatment and product form, measured at room temperature where the source says so.
- Yield strength: the ranges overlap (Stainless steel 170 to 1,896 MPa; Carbon and alloy steel 170 to 1,330 MPa).
- Tensile strength: the ranges overlap (Stainless steel 380 to 2,200 MPa; Carbon and alloy steel 310 to 1,600 MPa).
- Density: the ranges overlap (Stainless steel 7.6 to 8.1 g/cm³; Carbon and alloy steel 7.67 to 8.03 g/cm³).
- Young's modulus: the ranges overlap (Stainless steel 174 to 220 GPa; Carbon and alloy steel 190 to 210 GPa).
- Thermal conductivity: the ranges overlap (Stainless steel 12 to 30 W/(m·K); Carbon and alloy steel 25 to 93 W/(m·K)).
- Melting point: the ranges overlap (Stainless steel 1,300 to 1,532 °C; Carbon and alloy steel 1,432 to 1,526 °C).
- Thermal expansion: the ranges overlap (Stainless steel 9.9 to 20.5 ppm/K; Carbon and alloy steel 3.44 to 14.6 ppm/K).
- Yield strength for each unit of density (calculated from each grade's midpoint values): Stainless steel 23.8 to 248 MPa per g/cm³; Carbon and alloy steel 32.6 to 115 MPa per g/cm³.
"Higher" means the whole range is higher, not just one value. Where a value is a specified minimum, the table says "at least".
Side by side
| Property | Stainless steel | Carbon and alloy steel |
|---|---|---|
| Yield strength | 170 to 1,896 MPa | 170 to 1,330 MPa |
| Tensile strength | 380 to 2,200 MPa | 310 to 1,600 MPa |
| Density | 7.6 to 8.1 g/cm³ | 7.67 to 8.03 g/cm³ |
| Young's modulus | 174 to 220 GPa | 190 to 210 GPa |
| Thermal conductivity | 12 to 30 W/(m·K) | 25 to 93 W/(m·K) |
| Melting point | 1,300 to 1,532 °C | 1,432 to 1,526 °C |
| Service temperature | 232 to 1,100 °C | no data |
| Thermal expansion | 9.9 to 20.5 ppm/K | 3.44 to 14.6 ppm/K |
| Yield strength per densitycalculated | 23.8 to 248 MPa per g/cm³ | 32.6 to 115 MPa per g/cm³ |
When to use which
| Material | Best for | Weakest at |
|---|---|---|
| Stainless steel 304 | Corrosion-resistant housings, fasteners and tanks where ordinary steel would rust | Chloride pitting in acidic solutions, and low strength compared with precipitation-hardened steels |
| Stainless steel 316 | Chloride-bearing and marine-grade service where 304 would pit, in annealed sheet, bar and plate | Crevice and pitting attack in seawater condenser tubes, intergranular attack after heating between 500 and 900 C, and modest strength next to precipitation-hardened grades |
| Stainless steel 316L | Welded parts in chloride or marine service, and vacuum hardware that is vacuum-fired | Long holds near 650 C form sigma phase, and seawater service needs a pitting resistance equivalent number greater than 40 (Wikipedia) |
| Duplex stainless steel 2205 | Chloride-bearing and sour service where 300-series steels crack, in welded pipe, tube, sheet and plate (ATI, Alleima) | Extended exposure at 343 to 530 C (475 C embrittlement), welds made with straight chromium filler, and sour service above 232 C (ATI, Alleima) |
| Super duplex stainless steel 2507 | Chloride-bearing seawater, subsea and sour oil and gas service that needs high strength and pitting resistance, in solution-annealed tube, bar and forgings | Prolonged exposure above 250 °C, which lowers impact strength, and hydrogen-induced cracking in cathodically protected subsea steel |
| 17-4 PH stainless steel | High-strength fittings, fasteners, shafts and valve parts that need more strength than 304 and moderate corrosion resistance | Stress corrosion cracking and pitting in peak-aged (H900) material, and crevice corrosion in stagnant salt water |
| Stainless steel 440C | Bearings and valve parts that must be hard and wear-resistant in the hardened and tempered condition (Carpenter, Aalco, Rolled Alloys) | Corrosion resistance in the annealed state or after tempering above about 800 F (427 C), and service above about 400 C (NASA 2018 maximum use temperature) |
| Stainless steel 410 | Hardened and tempered valve, shaft and fastener parts that need strength and a magnetic response | Chloride, marine and strong-acid service, and toughness after tempering at 482 to 538 C |
| Stainless steel 430 | Sinks, appliance trim and architectural cladding, where economy and moderate corrosion resistance matter more than strength (ATI) | Welds and sea water. Welds lose ductility and corrosion resistance, and the datasheet says the grade is not resistant to sea water (Deutsche Edelstahlwerke) |
| Martensitic stainless steel 13Cr-4Ni (UNS S41500) | Quenched and tempered turbine, pump and valve parts that need good strength and low-temperature toughness, in low-chloride media with polished surfaces | Chloride pitting (DEW: slight attack with a risk of pitting in saturated NaCl at 20 C), the 23 HRC cap for sour gas, and poor weldability (DEW) |
| Stainless steel 301 | Springs, clips and light formed structures where cold-work strength matters more than corrosion resistance | Chloride pitting (critical pitting temperature below 10 C in Outokumpu's test) and carbide precipitation after welding or holding at 427 to 816 C |
| Stainless steel 303 | Heavily machined parts in mild service, such as screws, nuts, bolts, shafts and fittings (Aalco, UPMET) | Chloride and marine service, where Aalco says 303 is not suitable, and welded joints, where Aalco says weldability is poor |
| Lean duplex stainless steel 2304 | Chloride-bearing process piping and heat exchangers, pulp and paper equipment, and strength-limited structures where 304 or 316 would crack or be too weak (Alleima, ATI) | Exposure above about 315 C (600 F), where 475 C embrittlement can follow (ATI); prolonged exposure above 280 C (Alleima); weld metal without an overmatched filler (ATI) |
| Stainless steel 409 | Automotive exhaust systems and heat exchangers, where corrosion protection is needed beyond carbon steel (Combined Metals) | Pitting and intergranular corrosion: Outokumpu prints a critical pitting temperature below 10 °C and N/N for intergranular corrosion, and Aalco limits welded sheet to about 2.5 mm thick |
| Stainless steel 444 | Hot water tanks, heat exchangers and solar tanks in chloride-bearing water, where resistance to chloride stress cracking matters (ATI, Ugitech, Aperam) | Boiling 10 percent sulphuric and sulfamic acids, where ATI's table shows corrosion above 1000 mils per year, and toughness at transition temperatures, welds included (Aperam) |
| AISI 302 stainless steel | Springs, washers, screens and wire parts that need an 18-8 stainless steel with more carbon than 304 for strength, while keeping ductility (Elgiloy datasheet) | Strength in the annealed state (about 290 MPa typical yield), and ductility after heavy cold work (elongation falls from 48 % at 0 % cold work to 2.2 % at 80 % cold work, fwmetals table) |
| Stainless steel 304L | Welded parts in corrosive service, where the as-welded condition must resist carbide precipitation | Sea water and chloride service: Carpenter rates 304 and 304L restricted in sea water, and no pitting number for 304L was found |
| Stainless steel 310S | Furnace and heat-treatment parts that run hot in oxidising air up to about 1,050 °C, with good creep strength and oxidation resistance | Sulphur-bearing hot gases, which cut the service limit to 950 °C, and long exposure between 650 and 900 °C, which causes sigma-phase embrittlement and chromium-carbide sensitisation |
| AISI 317L stainless steel | Chloride pitting resistance in process equipment, with a low-carbon grade that limits sensitization in welds | Strength in the annealed state (205 MPa minimum yield) and chloride stress cracking above about 49 °C |
| AISI 321 stainless steel | Welded parts that run hot in oxidising air, from 427 to 850 degC: titanium holds the grade against carbide precipitation in the 800 to 1500 degF range | Strength when annealed (about 241 MPa typical yield) and cold-work strength only, plus exposure of 900 to 1500 degF for long periods, which lowers general corrosion resistance |
| AISI 347 stainless steel | Welded hot-service parts that cannot be re-annealed afterwards: niobium stabilisation resists intergranular attack, and the grade is rated to 800 °C in air | Strength when hot: tensile strength falls from 93.3 ksi at 68 °F to 69.5 ksi at 800 °F (Rolled Alloys), and no vacuum, radiation or atomic-oxygen data were found |
| AISI 347H stainless steel | Welded parts for hot service in air and steam, where creep strength to 1500 degF is needed and niobium stabilisation resists intergranular attack in the as-welded condition | Strength when hot: typical tensile strength falls from 93.3 ksi at 68 degF to 69.5 ksi at 800 degF (Rolled Alloys), and no vacuum, radiation or atomic-oxygen data were found |
| Super-austenitic stainless steel 904L | Sulfuric and phosphoric acid plant, seawater condensers and heat exchangers, and pulp bleaching, in annealed sheet, plate, strip and tube, where 316L or 317L would corrode | Halide-containing acids and boiling magnesium or lithium chloride, where ATI's U-bend test cracked the alloy, and crevices in chloride water (ATI G-48 onset at 18 °C) |
| Nitronic 60 stainless steel | Fasteners, pins, bushings and valve trim that must resist galling and wear while staying austenitic and low in magnetic permeability | General corrosion resistance falls between Types 304 and 316, the alloy is hard to machine, the high-strength bar cannot be hot worked or welded without losing strength, and the sources print no space-environment data |
| Lean duplex stainless steel 2101 (UNS S32101) | Chloride-bearing process equipment where a 300 series grade is too weak or too prone to chloride stress cracking, and nickel cost matters: the grade gives about double the 0.2 % yield of 304 and 316 and no SCC in the boiling CaCl2 U-bend test | Use above about 300 °C: Atlas says held above 300 °C the grade embrittles and only a full solution anneal restores it, and no space-environment data (radiation, outgassing, cryogenic toughness) were found |
| Stainless steel 430F | Machined parts cut from bar on automatic screw machines, where machinability matters more than corrosion resistance or weldability (Atlas, Deutsche Edelstahlwerke) | Corrosion and welding. The sulphur addition reduces corrosion resistance, especially pitting and crevice attack, and weldability is poor (Deutsche Edelstahlwerke) |
| Stainless steel 410S | Ferromagnetic, weldable stainless parts for hot or mildly corrosive service, such as distillation trays, tower packing and exhaust components, where the 410 hardening response is not wanted | Chloride and marine service (no 410S test data was found), and room-temperature brittleness in thick sections (Jacquet) |
| AISI 416 stainless steel | Shafts, axles, gears, valve and pump parts and screw-machine parts that must be cut quickly and then hardened, kept away from chloride exposure | Corrosion resistance. The sulfur addition lowers it below the non-free-machining grade 410, and the Aalco datasheet calls high-sulfur free-machining grades totally unsuitable for marine or chloride exposure |
| Stainless steel 420 | Hardened wear parts, blades and bearing-type components that need high strength and edge retention, from one steel that reaches 48 HRC after tempering at 440 °F | Corrosion resistance and ductility: it resists corrosion less well than austenitic grades, and it loses strength when tempered at 1000 °F (158.5 ksi tensile) |
| Stainless steel 431 | High tensile and torsional strength in shafts, valve stems and pump parts that also need reasonable corrosion resistance (Smith Metal, Smiths High Performance) | Welding and cold forming: welds crack unless preheated, and the grade is not recommended for cold heading or bending (Smiths High Performance, Voestalpine) |
| Martensitic stainless steel | Quenched and tempered shafts, axles and pump parts that need strength, toughness and good general corrosion resistance, with limited marine exposure (DEW) | Chloride pitting: DEW gives a risk of pitting corrosion in saturated sodium chloride and in sea water at 20 C, and welds need heat treatment afterwards (DEW) |
| 17-7 PH stainless steel | Springs, Belleville washers, eyelets and flat springs that need high strength and stainless corrosion resistance, with formability in the soft state | Stress corrosion cracking in chloride and in nitrogen tetroxide/hydrazine propellant, in every heat-treated condition except CH 900; ductility in CH 900 (2 % elongation) |
| PH 15-7 Mo stainless steel (15-7 PH) | Springs, retaining rings and seal rings that need high strength with a low-distortion hardening heat treatment (ATI and Ulbrich list these uses) | Stress corrosion cracking in salt water: the 1969 NASA test found the alloy cracked in all conditions except CH 900, and corrosion resistance is below Type 304 (ATI) |
| 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. |
Where each is used
| Material | Use |
|---|---|
| Stainless steel 304 | Spacecraft propellant tank |
| Stainless steel 304 | Fasteners and screws |
| Stainless steel 304 | Architectural cladding |
| Stainless steel 316 | Aerospace structures |
| Stainless steel 316 | Chemical storage, food processing and oil refining equipment |
| A36 structural carbon steel | General construction and structural framing |
| A36 structural carbon steel | Girders, structural shapes and angle iron |
| A36 structural carbon steel | Bolted and welded structural joints |
| Carbon steel 1018 | Shafts, pins and gears |
| Carbon steel 1018 | Low-stress structural components |