Type 304 stainless steel is basically the same as Type 302 except for a higher chromium and lower carbon content. Its lower carbon minimizes chromium carbide precipitation due to welding and its susceptibility to intergranular corrosion. In many instances, Type 304 can be used in the "as welded" condition while Type 302 must be annealed in order to retain adequate corrosion resistance.

Type 304 has the same excellent combination of strength, corrosion resistance and workability as Type 302, and it costs the same. Consequently this type is widely used and is more popular than type 302.

Type 304L is an extra low carbon variation of Type 302. The .03% maximum carbon content eliminate carbide precipitation due to welding. Consequently, the alloy can be used in the "as welded" condition even in severe corrosive conditions. In many cases it eliminates the necessity of annealing weldments except for applications where stress relief is specified. Type 304L has slightly lower mechanical properities than Type 304.

Types 304 and 304L stainless steel is available in:

• Bar
• Wire
• Sheet
• Strip
• Billets

The following specifications are generally applicable:

Sheets and Plates

• MIL-S-5059
• AMS 5513
• ASTM A 167
• ASTM A 24

Bars, Wire and Billets

• MIL-S-7720
• QQ-S-763
• AMS 5639
• ASTM A 276
• ASTM A 479

• Low carbon Content of 304 and 304L is more conducive to welding than type 302
• Applications include architectural mouldings and trim and kitchen equipment
• Alloys are widely used for welded components of processing equipment for textile

Types 304 and 304L have very good drawability. Their combination of low yield strength and high elongation permits successful forming complex shapes. However,these grades work harden rapidly. To relieve stresses produced in severe forming spinning, parts should be full annealled or stress-relief annelaed as soon as possible after forming

• When machined, Types 304 and 304L will work-harden. Therefore tools must not ride or glaze the surface without cutting. Heavy feeds and slow speeds are recommended

• Like Type 302, Types 304 and 304L stainless steel have excellent resistance to a wide range of corrosive media and to atmospheric exposures. The low carbon content of Type 304 and especially 304L, by reducing or eliminating carbide precipitation due to welding, makes these types of stainless suitable for a much wider range of corrosive service than Type 302.

• Both these stainless steels are readily welded by most welding processes such as TIG, MIG and resistance welding. However, all arc welding not using a shielded gas should have the filler rods coated. Type 308 and 308L welding rods are suggested for best results.