FERRITIC STAINLESS STEEL SHEET FOR FORMED SPRING AND MANUFACTURING METHOD THEREFOR

• Main Authors: YASHIRO TOSHIYUKI, HIRANO TAKAAKI, KAJIYA TSUTOMU
• Format: Patent
• Language: English
• Published: 07.09.2006
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PROBLEM TO BE SOLVED: To provide an inexpensive ferritic stainless steel sheet for a formed spring, which has spring characteristics comparable to those of austenitic stainless steel used for various formed springs, and uses few expensive component elements such as Ni, and to provide a manufacturing method therefor. SOLUTION: The ferritic stainless steel for the sheet comprises not more than 0.03% C, not more than 0.03% N, not more than 1.00% Si, not more than 1.00% Mn, 16-20% Cr, not more than 0.60% Ni, 8×(C+N)% to 0.80% Nb by mass% and the balance Fe with unavoidable impurities. The method for manufacturing the sheet comprises the steps of: cold-rolling the ferritic stainless steel so as to store distortion corresponding to that stored by cold rolling with a reduction of 15% or higher inside it; and subjecting to final heat treatment in a temperature range of 550 to 750°C. Thus manufactured stainless steel sheet has a 0.2% yield strength σ of 600 MPa or higher, and such elongation (%) as to satisfy both relationships of ≥-0.02×σ+22 and ≥5. COPYRIGHT: (C)2006,JPO&NCIPI