ATI Allegheny Ludlum Stainless Steel Type 439/AL 439HP™ (ASTM XM-8; UNS S43035)

Allegheny Ludlum Stainless Steel Type 439, a titanium stabilized, 18 percent chromium alloy, also known as ASTM XM-8 and by the UNS designation S43035, is a ferritic stainless steel designed to resist corrosion in a variety of oxidizing environments from fresh water to boiling acids. It may be used in either the annealed, cold formed or as-welded condition. Type 439 may also be used in many oxidizing environments where Type 304 is considered adequate in term of general corrosion resistance but is subject to chloride stress corrosion cracking.The composition of Type 439 stainless steel has been balanced to provide a completely ferritic structure at all temperatures, to avoid the loss of ductility after welding and to provide resistance to intergranular corrosion. Type 439 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 and ideal consideration for many applications. For shell and tube heat exchangers where carbon steel shells are used with Type 439 tubes the close match of thermal expansion coefficients may possibly eliminate the need for an expansion joint in the heat exchanger. Type 439 has a low carbon content making it an attractive consideration for nuclear applications. Type 439 also provides good oxidation and corrosion resistance for many automotive exhaust system components and residential furnace primary heat exchangers.Information provided by Allegheny Ludlum Corporation.