STEEL FOR LEAF SPRING WITH HIGH FATIGUE STRENGTH AND LEAF SPRING PARTS

摘要

Disclosed 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. (FIG. 1)