| 摘要 |
<p>A high-strength steel which is suppressed in the generation of blow holes in welding even when strengthened by nitriding; and a process for producing high-strength steel excellent in weldability with reduction in the rolling load. Specifically, a high-strength steel which contains not more than 0.05% C (by mass, the same applies hereinafter), not more than 1% Si, not more than 1.5% Mn, not more than 0.05% P, not more than 0.05% S, not more than 0.05% Al, 0.02 to 0.3% Ti, and not more than 0.020% N and has a ferrite single phase structure wherein at least 250 Ti nitride grains whose maximum sizes are 20nm or below are coherently precipitated per mum2. In the high-strength steel, Ti nitride grains whose maximum sizes are 6nm or below account for at least 80% of Ti nitride grains whose maximum sizes are 20nm or below.</p> |
