Stainless Steel Alloys

Series Groups

2XX Chromium-Nickel-Manganese Steels — Non-hardenable by heat treatment, austenitic, and non-magnetic hardenable by coldworking.

3XX Chromium-Nickel Steels — Non-hardenable by heat treatment, austenitic, and non-magnetic hardenable by cold working.

4XX Chromium Steels — Hardenable by heat treatment, martensitic, and magnetic.

4XX Chromium Steels — Non-hardenable, ferritic, and magnetic.

5XX Chromium Steels — Low chromium, heat resisting. (Note: Although these alloys are sometimes associated with the stainless family, they are not true stainless steels as they only contain from 4% to 6% chromium.)

Note that the precipitation-hardening type alloys are not covered by the three-digit numbering system.

AlloyDescription
301High work-hardening rate due to reduced chromium and nickel content.
302
General purpose material with greater corrosion resistance but less work hardening than Type 301. This is the basic alloy of the austenitic group often referred to as 18:8.
303Phosphorus and sulfur added for easier machining. For heavier cuts in automatic machining operations.
304Carbon lower to minimize carbide precipitation. Less heat sensitive than other 18:8 steels. Used in high-temperature applications.
304LExtra low carbon content to avoid harmful carbide precipitation in welding applications. Corrosion resistance comparable to Type 304.
316Contains molybdenum for better corrosion resistance—particularly to pitting.
316LCarbon lower than Type 316 to avoid carbide precipitation in welding applications.
321Titanium added to avoid chromium-carbide precipitation when heated. Good for welding.
410Basic martensitic type. General purpose, heat-treatable type used wher ecorrosion is not severe.
410 HTHeat treated version of Type 410. Basic martensitic type. General purpose, used where corrosion is not severe.
416Free machining variation of Type 410 by virtue of added sulfur.
420Hardenable stainless steel, which can be hardened to approximately Rockwell C 50.
430FFree machining version of Type 430. Non-hardenable by thermal treatment and is used for heat resistance and corrosion resistance under many conditions. Excellent machinability and good forming.
440CA high carbon type. Can be heat treated for high strength and hardness. Greater abrasion and wear resistance for use in bearing and bushing applications. Corrosion resistant only in the hardened condition.
15-5High strength, corrosion resistant and easy to heat treat. Use for high pressure applications.
17-4Chromium, nickel, copper, columbium, tantalum, and carbon balanced for high corrosion resistance and hardening by heat treatment.
AlloyDescription
301High work-hardening rate due to reduced chromium and nickel content.
302
General purpose material with greater corrosion resistance but less work hardening than Type 301. This is the basic alloy of the austenitic group often referred to as 18:8.
303Phosphorus and sulfur added for easier machining. For heavier cuts in automatic machining operations.
304Carbon lower to minimize carbide precipitation. Less heat sensitive than other 18:8 steels. Used in high-temperature applications.
304LExtra low carbon content to avoid harmful carbide precipitation in welding applications. Corrosion resistance comparable to Type 304.
316Contains molybdenum for better corrosion resistance—particularly to pitting.
316LCarbon lower than Type 316 to avoid carbide precipitation in welding applications.
321Titanium added to avoid chromium-carbide precipitation when heated. Good for welding.
410Basic martensitic type. General purpose, heat-treatable type used wher ecorrosion is not severe.
410 HTHeat treated version of Type 410. Basic martensitic type. General purpose, used where corrosion is not severe.
416Free machining variation of Type 410 by virtue of added sulfur.
420Hardenable stainless steel, which can be hardened to approximately Rockwell C 50.
430FFree machining version of Type 430. Non-hardenable by thermal treatment and is used for heat resistance and corrosion resistance under many conditions. Excellent machinability and good forming.
440CA high carbon type. Can be heat treated for high strength and hardness. Greater abrasion and wear resistance for use in bearing and bushing applications. Corrosion resistant only in the hardened condition.
15-5High strength, corrosion resistant and easy to heat treat. Use for high pressure applications.
17-4Chromium, nickel, copper, columbium, tantalum, and carbon balanced for high corrosion resistance and hardening by heat treatment.

Type Designations