Introduction the new grades of stainless steel 24511 and new national standards
Intergranular anti-corrosion technology during Stainless steel production
Stainless steel decorative tube, 201 stainless steel pipes, 304 stainless steel of decorative tube, 304 stainless steel pipe and other products will be processed in the following ways to improve their intergranular anti-corrosion abilities.
(1) Reduce the content of carbon steel and make it less than the saturated solubility in austenite at equilibrium: It solve the problem that chromium carbide (Cr23C6) is precipitated in the grain boundary fundamentally. Typically when the carbon steel is below 0.03%, it will meet the requirements of resistance to intergranular anti-corrosion. (2) By adding Ti, Nb, and other elements which can form stable carbides, it will be helpful to avoid Cr23C being precipitated in the grain boundary to prevent the intergranular corrosion of Austenite stainless steel. (3) By adjusting the ratio of austenitic and ferritic forming elements to make the steel has austenitic + ferritic duplex structure where ferrite accounts for 5% -12 %, this duplex structure is not easy to be in intergranular corrosion. (4) By using appropriate heat treatment, it can prevent intergranular corrosion and get the best corrosion resistance.