Method of producing members using a weldable steel of high strenght and high toughness.

摘要

Disclosed are a weldable steel of high strength and high toughness and a method of producing members of machine parts. The steel consists essentially of, by weight %, C: 0.10-0.16%, Si: 0.05-0.50%, Mn: 1.3-2.3%, Cu: up to 0.5%, Ni: up to 0.5%, Cr: up to 0.5%, Mo: up to 0.3% and Ti: 0.025-0.035%, and the balance of Fe and inevitable impurities, and satisfying the condition that the weld-cracking susceptibility, Pcm, defined by the formula 1A below is less than 0.35, and the condition that the manganese equivalent, Mneq, defined by the formula 2A below is larger than 2.0.
1A: Pcm=C(%)+Si(%)/30+Mn(%)/20+Ni(%)/60+Cr(%)/20+Mo(%)/15 +Cu(%)/20
2A: Mneq=Mn(%)+Cu(%)+Ni(%)/2+Cr(%)+Mo(%)