INVAR ALLOY WITH EXCELLENT WELDING HIGH TEMPERATURE CRACK RESISTANCE AND STRAIN CORROSION CRACK RESISTANCE

摘要

PURPOSE:To enhance welding high temperature crack resistance and strain corrosion crack resistance of an invar alloy by a method wherein, in an invar alloy, Co is limited to below a specific amount and, when S and Al are a minute amount, Mn is contained in a content of below a specific amount. CONSTITUTION:This invar alloy contains Ni; 34.5-37.5%, S; =0.015%, Al; =0.02%, O; =0.025%, Co; =0.05% and, when S is =0.005% and Al is = 0.005%, Mn; =1.2% and comproses a balance of Fe and inevitable impurities. By the above described limination of a Co amount, a property with excellent strain corrosion crack resistance is attained and, by including Mn; =1.2% when S is =0.005% and Al is =0.005% as well as Mn; 0.5-1.2% when S is =0.005% and Al is 0.005% or Al is =0.005% and S is 0.005%, welding high temperature crack resistance is enhanced.