HIGH STRENGTH AND TOUGHNESS SPRING STEEL WIRE HAVING EXCELLENT FATIGUE FRACTURE RESISTANCE, SPRING FOR THE SAME AND METHOD FOR MANUFACTURING THEREOF

摘要

PURPOSE: A high-strength and high-toughness spring steel wire having fatigue fracture resistance, a spring using the same and a manufacturing method thereof are provided to prevent the generation of boron carbide which can cause early fracture. CONSTITUTION: A steel sheet is drawn to be a steel wire. A steel sheet is drawn to be a steel wire. The steel wire is heated to the temperature of 850-1000 degrees Celsius. The heated state maintains over one minute. The steel wire is formed in austenite. The steel wire formed into austenite is oil-cooled. The oil-cooled steel wire is tempered at a temperature of 350 degrees. The steel wire includes Ni of 0.01~2.0% and Cu of 0.01~1.0%. When the steel wire is formed into austenite, the steel wire is heated at the temperature range of 850~980 degrees Celsius for 1~5 minutes.