Steel for leaf spring with high fatigue strength and leaf spring parts

摘要

pDisclosed is steel for a leaf spring with high fatigue strength containing  in mass percentage  C: 0.40 to 0.54%  Si: 0.40 to 0.90%  Mn: 0.40 to 1.20%  Cr: 0.70 to 1.50%  Ti: 0.070 to 0.150%  B: 0.0005 to 0.0050%  N: 0.0100% or less  and a remainder composed of Fe and impurity elements. Also disclosed is a high fatigue-strength leaf spring part obtained by forming the steel. The steel for a leaf spring is prepared to have a Ti content and a N content to satisfy a relation of Ti/N=10. Preferably  the leaf spring part is subjected to a shot peening treatment in a temperature range of the room temperature through 400?C with a bending stress of 650 to 1900 MPa being applied to it./p