PURPOSE: To prepare low temp. steel for a welding joint part excellent in toughness, by subjecting a slab having a specific composition containing C, Si, Mn, Si, acid soluble Al and Cr or Mo and comprising the remainder Fe to hot rolling and heat treatment under a specific condition.
CONSTITUTION: A slab containing 0.01W0.08% C, 0.05W0.50% Si, 0.05W0.90% Mn, 8.00W10,00% Ni, 0.01W0.10% acid soluble Al and, further, 0.10W1.00% Cr and/or 0.05W0.50% Mo and comprising the remainder Fe and inevitable impurities is subjected to hot rolling under a condition for imparting a cumalative draft of 60% or more at 50°C or less and, directly after rooling, the rolled slab is tempered and succeedingly annealed at a temp. of a Ac1 transformation point or less. By this method, the toughness in both fine grain region and (α+γ) two- phase region among welding heat parts can be especially improved and low temp. 9% Ni steel excellent in the toughness of a welding joint part can be obtained.
KAJI HARUO
ISHIOKA CHISATO
KOBAYASHI YOUICHIROU
| JPS5623224A | 1981-03-05 | |||
| JPS5457418A | 1979-05-09 | |||
| JPS5113308A | 1976-02-02 |