Cold mannered null cold in order to produce the billet which is disconnected to the band steel or the band-like of the marageing steel which is rolled

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a maraging steel having an excellent fatigue resistance.;SOLUTION: Before applying a hardening heat-treatment, a strip steel or a steel slab is subjectedc to a cold-plastic deformation at 30% cold-working ratio, and fine crystal particle having 8 ASTM index, is obtained and the chemical composition of a maraging steel is composed by wt.% of 12-24.5% Ni, 2.5-12% Mo, 4.17-20% Co, ≤0.15% Al, ≤0.1% Ti, ≤0.0003% N, ≤0.1% Si, ≤0.1% Mn, ≤0.005% C, ≤0.001% S, ≤0.005% P, ≤0.0003% H, ≤0.001% O and the balance Fe with impurities depending to the refining and further, the following chemical compositions satisfies the following relationships: 20%≤Ni+Mo≤27%, 50≤Co×Mo≤200, Ti×N≤20×10^-4.;COPYRIGHT: (C)2009,JPO&INPIT