ASTM A240 GRADE 304/304L STAINLESS STEEL PLATES AND SHEETS

One of the most versatile and commonly used stainless steels on the market, Grade 304 stainless steel is the most standard used alloy of this type. Essentially, Grade 304 is an austenitic chromium alloy which is also known as an “18/8” stainless as the make-up of the steel is 18% chromium and 8% nickel.

The chromium content promotes the material’s considerable resistance to the effects of corrosion and oxidation. The stainless steel alloy resists most oxidizing acids and will withstand ordinary rusting though this does not mean that the steel will not tarnish over time. The steel needs to be cold worked to generate higher tensile strength. For stainless steel sections which are welded heavily, post-weld annealing may be necessary to provide maximum corrosive resistance.

Type 304 and Type 304L have very similar chemical and mechanical properties and are often included on a single material test certificate when the actual properties of a stainless steel plate meet the criteria of both types. This is a very common occurrence. Type 304L is a variation of Type 304 and has a lower carbon content which improves weldability and lowers the risk of reduced corrosion resistance around the weld. Type 304L also has a slightly lower yield and tensile strength than Type 304.

As with most steel plate products a number of different designations are used for these steels. The most common are: