347/347H Stainless Steel

UNS S34700

Grade 347/347H is an austenitic stainless steel made of .08% maximum carbon, 17% to 19% chromium, 2% maximum manganese, 9% to 13% nickel, 1% maximum silicon, traces of phosphorus and sulfur, 1% minimum to 10% maximum columbium and tantalum with the balance of iron. Grade 347 is advantageous for high temperature service because of its mechanical properties; it also has excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800° to 1500° F. It is similar to Grade 321 with respect to intergranular corrosion which is achieved through the use of columbium as a stabilizing element to maximize this feature. Grade 347 cannot be hardened through heat treating, but elevated properties may be obtained through cold reduction.