PRODUCTION OF LOW CARBON STEEL OF SUPERIOR STRESS CORROSION CRACKING RESISTANCE

摘要

PURPOSE:To improve the stress corrosion cracking resistance by heating low carbon steel to the specific temperature range and cooling the same at a cooling rate of 100 deg.C or more in one hour. CONSTITUTION:The low carbon steel containing C; 0.001-0.07%, Si0.5%, Mn; 0.40-3.0% and sol. Al0.10% or further containing one or two or more kinds of Cu; 0.05-0.3%, Cr; 0.05-1.0%, Ni; 0.05-0.60%, Mo; 0.01-0.50% is heated to the temperature range of the AC1 point of said steel +30 deg.C to AC3 point. Ferrite grain boundaries change zigzag, resulting in decreased stress corrosion cracking sensibility. By cooling the later cooling at a cooling rate of 100 deg.C/h or more, spheroidization of the pearlite of the ferrite grain boundaries is prevented and the increase in stress corrosion cracking sensibility is prevented.