STEEL WIRE FOR HIGH-STRENGTH SPRING HAVING EXCEPTIONAL COILING PERFORMANCE AND HYDROGEN EMBRITTLEMENT RESISTANCE, AND METHOD FOR MANUFACTURING SAME

摘要

The present invention provides a spring steel wire that demonstrates high strength without being doped with large quantities of alloy elements, and makes it possible to obtain a cold winding spring having exceptional coiling performance and improved hydrogen embrittlement resistance. The spring steel wire is characterized in comprising 0.40 to 0.65 percent by mass of C, 1.0 to 3.0 percent by mass of Si, 0.6 to 2.0 percent by mass of Mn, 0.015 mass percent or less (excluding 0%) of P, 0.015 percent by mass or less (excluding 0%) of S, and 0.001 to 0.10 percent by mass of Al, the balance being made up of iron and impurities; 70% or more of the area of the entire structure being tempered martensite, and 6 to 15% of the area of the entire structure being residual austenite, the old austenite crystal grain size number as determined using the method defined in JIS G 0551 being 10.0 or higher and the tensile strength being 1900 MPa or higher.