| 摘要 |
PROBLEM TO BE SOLVED: To provide a spring steel having fine tempered martensite enabling an inexpensive steel to have high strength and high toughness, and a spring.SOLUTION: A method of producing a spring steel is provided that performs: a hardening step of quickly cooling a steel material from an austenite range of Ac3 point or higher to generate martensite, the steel material having a composition containing, by mass%, C:0.10 to 0.90%, Si:0.10 to 2.50%, Mn:0.10 to 2.00%, Cr:0.10 to 2.00% and the balance Fe with inevitable impurities; a hot plastic working step of increasing a temperature of the steel material to 500 to 650°C at a rate of 2°C/sec. or more, holding the steel material for 0 to 5 sec. and then conducting plastic working with equivalent distortion of 0.7 or more; an ultra short time hardening step of increasing the temperature of the steel material to an austenite range of Ac3 point or higher at a rate of 25°C/sec. or more, holding the steel material for 0 to 2 sec. and quickly cooling it to generate fine martensite; and a tempering step of heating and holding the steel material.SELECTED DRAWING: None |
