Type 420

• Hardenable, martensitic stainless steel with corrosion resistance similar to Type 410
• Higher carbon content to increase strength and hardness over Type 410
• Maximum corrosion resistance only in the fully hardened condition or fully hardened and stress relieved condition
• Never used in the annealed condition

Available Forms

Type 420 stainless steel is available in:

• Bar
• Wire
• Billets

Specifications

Type 420 Stainless Steel (bar, wire and billets) is covered by the following specifications:

Typical Applications

• Specified for a wide variety of applications where good corrosion and hardness in the range of C50 to C54 is required
• Applications include cutlery, surgical and dental instruments, scissors, tapes and straight edges, gauges, needle valves, ball check valves, gear shafts, cams, pivots, ball bearings and hand tools
• Not normally used at temperatures exceeding 800° F due to rapid softening and loss of corrosion resistance

Machinability

Type 420 Stainless Steel machines like a high carbon steel. Chips are tough and stringy. Carbide cutting tools are recommended because this alloy has an abrasive action on tools.  For parts that require extensive machining, the two free-machining versions, Type 430 and Type 430F Se offer fabrication economies.

Weldability

Because of the air hardening characteristics of Type 420, it has only fair weldability and is seldom welded.

Formability

If annealed for maximum softness, Type 420 can be moderately cold formed, and cold headed. It can be readily forged and hot-headed.  Preheating prior to hot working insures the best results.  Because this steel is air hardening, all hot worked parts should be furnace cooled to prevent cracking.

Corrosion Resistance

Type 420 has its full corrosion resistance only in the hardened or hardened and stress relieved conditions. In these conditions its corrosion resistance is similar to Type 410. Type 420 resists corrosion by the atmosphere, fresh water, mine water, steam, carbonic acid, crude oil, gasoline, perspiration, alcohol, ammonia, mercury, sterilizing solutions, soaps, and other similar corrosive media.

Heat Treatment

ANNEALING: For maximum softness, heat uniformly to 1600-1650° F and cool down slowly in the furnace.
HARDENING: Preheat, then heat to 1800-1950° F, soak at temperature and air cool or quench in warm oil.
STRESS RELIEVING:  Heat at 300-800° F for 1 to 3 hours, cool in air or quench in oil or water.