Austenitic stainless steels are chrominum-nickel-managanese and chromium-nickel compositions, which can be hardened solely by cold working; heat treatment serves solely to soften them. they're non-magnetic within the annealed condition, though some might become slightly magnetic after cold working.
The austenitic group of stainless steels is characterised as having wonderful corrosion resistance, outstandingly good formability, and therefore the ability to develop high strength. within the annealed condition, they posses most ductility, good yield and tensile strength, high impact strength, and good notch toughness.
Typical of this group is type 304, also wide called 18-8 stainless, a general used stainless steel. There ar numerious compositions in this group. In these variations, (1) the chromium/nickel ratio has been modified to enhance the forming characteristics(Types 301 and 305), (2) the carbon content has been reduced to stop carbide precipitation in weldments.(Types 304L, 316L and 317L), (3) titanium or columbium has been added to stop carbide precipitation ensuing from exposure to high temperature(Type 321 and 347), (4) Mo has been added or the chromium and nickel contents are added to enhance corrosion or oxidization resistance (such as types 316 and 317 with Mo, and 309 and 310 with higher alloy content), and (5) sulfur to Se has been added or increased to enhance machining characteristics ( types 303 and 303 Se).
The two hundred Series stainless steels (Types 201, 202, and 205) just like the 300 Series types except that Mn replaces part of the nickel, and those alloys have higher yield and tensile strengths.