| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that, in the conventional technique, when the strength of a steel is made higher, sufficient toughness can not be imparted to a laser weld metal zone and a weld heat-affected zone (HAZ). SOLUTION: The steel has a composition comprising 0.05 to 0.13% C,≤0.35% Si, 0.5 to 2% Mn,≤0.01% P and≤0.005% S, and in which Ceq=C+Mn/6+Si/24+Ni/40+Cr/5+Mo/4+V/14 satisfies 0.45 to 0.55%, and the balance Fe with inevitable impurities. Regarding the steel, the grain size of austenite in a laser weld metal zone upon laser welding is≤100μm, and also, the ratio occupied by martensite in its microstructure is≥75%. COPYRIGHT: (C)2008,JPO&INPIT
|
