UNS S43035
Type 439 is a titanium stabilized, 18 percent chromium alloy that is a ferritic stainless steel designed to resist corrosion in a variety of oxidizing environments from fresh water to boiling acids. Type 439 may also be used in many oxidizing environments where Type 304 is considered adequate in terms of general corrosion resistance but is subject to chloride stress corrosion cracking. This variation does not require annealing after welding to restore ductility or to provide intergranular corrosion resistance.
Excellent resistance to stress corrosion cracking, good weldability, high thermal conductivity and low thermal expansion characteristics make Type 439 stainless steel an ideal consideration for many applications.