Abstract
A creep tempering is done in production process of a spring designed for a fuel-injection nozzle of diesel engine. It is because that creep deformation occurs during use at high temperature and mechanical properties may change. But, conditions (temperature, time) in the creep tempering depend on empirical data that are not necessarily reasonable. In this study, effects of creep tempering on mechanical properties and residual stress of spring are investigated experimentally and theoretically. It is found that shear residual stress increases and spring constant does not so change after creep tempering process. Calculation methods of both shear residual stress and shear creep constitutive expressions of spring are proposed.
