HIGH-STRENGTH STEEL EXCELLENT IN WELDABILITY AND PROCESS FOR PRODUCTION THEREOF

摘要

The present invention is even strengthened by the nitriding , which can suppress the occurrence of the blow holes in the welding provides a high strength steel . It also provides a way to manufacture these weldability while reducing the rolling load to excellent high-strength steel . The present invention , C: 0.05% or less ( mean % by mass or less , relative to the same chemical composition .), Si: less than 1%, Mn: less than 1.5%, P: 0.05% or less , S: 0.05% or less, Al: 0.05% or less , Ti: 0.02 ~ 0.3%, and N: 0.020% or less comprising a metal and organizations ferrite phase , and Ti nitride is not more than the maximum diameter 20 , 1 ² per More than 250 high-strength steel , which is a matched precipitation . The high-strength steel material , the maximum diameter is less than or equal to the number of Ti nitride 6 is , the maximum diameter is less than 80 % relative to the number of Ti nitride or less 20 .