STEEL FOR MANUFACTURING SPRING HAVING LOW DECARBURIZATION RATIO AND MANUFACTURING METHOD OF THE SAME

摘要

A steel for a spring in which decarburization is less and a manufacturing method thereof is provided to reduce the decarburization caused from that carbon reacts to the external atmosphere by making a combined oxide layer. A steel for a spring in which decarburization is less comprises as follows. An internal unit of the steel material is consisting of pearlite and ferrite. The fraction of the low temperature structure is 1% or less within the internal unit of the steel material. An oxide layer of Cu and Ni is formed on the surface of the steel material. Ni produces the scale layer in which the base material and adhesion are improved in order to efficiently suppress the surface decarburization. C prevents the surface decarburization along with the Ni, and improves the corrosion resistance. B improves the corrosion resistance and increases the grain boundary intensity and hardenability.