Is superior in dimensional stability at the time of the low temperature annealing the stainless steel steel null for the spring

摘要

PURPOSE: To obtain steel for a spring in which the dimensional change is hard to occur at the time of low temp. annealing treatment after spring forming by subjecting steel constituted of a polyphase mixed structure to solution treatment and regulating the volume ratio of body-centered cubic lattices contained therein into a specific one. ;CONSTITUTION: A steel material constituted of a polyphase mixed structure contg. a face-centered cubic lattice phase and a body-centered cubic lattice phase and subjected to solution treatment is used as a raw material, which is subjected to forming to regulate its dimension into a prescribed shape one to obtain the steel for a spring. At this time, the volume ratio of the body- centered cubic lattice phase contained in the steel subjected to solution treatment is regulated to 30 to 70%. In this steel, the dimensional changes of the face- centered cubic lattice phase and body-centered cubic lattice phase are mutually compensated in low temp. annealing after spring forming, and the dimensional variation can securely be reduced in the extreme. Thus, by using this steel for a spring, the productivity of springs improve without requiring a preliminary test, and the high accuracy of the spring dimension after annealing can be attained.;COPYRIGHT: (C)1995,JPO