PROCESS FOR PRODUCING HIGH-STRENGTH SPRING

摘要

A process for producing a high-strength spring capable of having a compressive residual stress greater than in the prior art. In particular, the process comprises subjecting to shotpeening a spring having undergone final heating, such as tempering (for heat-treated spring) or stress relieving annealing (for cold formed spring), while the surface temperature of the spring is in the range of 265 to 340°C (preferably 300 to 340°C). The spring after shotpeening is quenched. It is preferred that setting be performed prior to shotpeening, or after shotpeening but before quenching. The quenching can be accomplished by water cooling or oil cooling with no preference. When the wire diameter of the spring is small, forced air cooling can be used.