Stainless 420F

Annealing Procedure

1550-1650 F (843-900 C), slow furnace cooling.

Applications

Dental and surgical instruments, cutlery, pump shafts, gears pinions and cams, steel balls, and various hand tools. Not recommended for vessels containing high pressure gases or liquids or for plastic molds where high surface finishes are required.

Cold Workability

420F will withstand only minor cold work. Radical forming operations will result in cracking.

Hardening Procedure

Soak at 1850-1950 F (1010-1066 C) at quench in heated oil.

Hot Workability

Bring temperatures slowly up to 1400 F (760 C), then on to 2000-2200 F (1097-1204 C), after working, furnace cool slowly to avoid cracking. Reheat often to keep the working temperature above 1600 F.

Machinability

Good machining characteristics due to the addition of sulfur. High speeds and feeds combined with short brittle chips.

Principle Design Features

This alloy is a general purpose free machining version of 420 stainless, a heat treatable chromium steel.

Tempering Procedure

300-400 F (149-204 C), air cool for maximum hardness (Rc 52) and corrosion resistance.

Weldability

Not commonly welded due to its air hardening characteristics. Welding may be performed after preheating to 300-400 F (149-204 C) with post weld tempering at temperature for 2 hours . Filler metal should be AWS E/ER420.