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METALWORKING GUIDES

TYPE 302 STAINLESS

Stainless Type 302, once the most widely used grade, is a slightly higher carbon version of Type 304 and is most frequently used for wire applications. In the annealed condition it is austenitic, nonmagnetic, extremely tough and ductile, and has excellent corrosion resistance.

Some typical applications are springs, stampings, moldings, woven screens, cables, etc. Specific uses are salt water fishing tackle, nitric acid vessels, dairy equipment, ice cream molds, camera parts, thermometers, and aerosol springs.

It is frequently used in the annealed condition for its non-magnetic properties, which are vital importance to certain instruments.

HEAT TREATMENT:

Annealing: Heat to 1850/2050^o F (1010/1121^o C) and quench in water. Brinell hardness approximately 150.

Hardening: Can be hardened only by cold working.

WORKABILITY:

Hot Working: Type 302 can be readily forged, hot headed, riveted and upset. Because of its high red-hardness, more power for a given reduction is required than with mild steel. Heat uniformly to 2100/2300^o F (1149/1260^o C). Do not forge below 1700^o F (927^o C). Forgings can be air-cooled without danger of cracking. For full corrosion resistance, forging must be annealed by heating to at least 1900^o F (1030^o C) and water quenched. If pieces are allowed to cool slowly, there is likely to be some carbide precipitation, which will result in interganular corrosion. 

Cold Working: Type 302 is readily fabricated by cold working. It is extremely tough and ductile and responds well to deep drawing, bending, forming and up-setting. After cold working, it is slightly magnetic. The tensile strength and hardness of Type 302 can be significantly increased by cold working.

Machining: Type 302 produces a long gummy chip, and chip curlers and breakers are important on the tool. Since it work hardens very rapidly, glazing can be prevented by keeping the tools cutting - increasing the feed and slowing the speed will also be helpful. In turning operations speeds of 70/80 sfm are suggested. It machines quite similar to copper-nickel alloys, except the Type 302 work hardens. The machinability can be somewhat improved by using moderately cold drawn bars.

Welding: Type 320 can be satisfactorily brazed and welded by all methods. The weld does not air-harden and is very tough. When weld rods are used, they should be AWS E/R 308. Due to carbide precipitation in the grain boundaries, welding may cause the problem of interganular corrosion. When corrosive conditions are severe, the weldment should receive a post weld heat treatment to solution the interganular carbide precipitation. A typical heat treatment would be 1900o F (1038o C) for one hour per inch of thickness and quench rapidly. Water quench if possible.

Forms Available:

Forgings and tube billets
Hot rolled bars
Cold drawn and ground bars
Wire and wire rods
Strip
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Last modified: March 03, 2002