화학공학소재연구정보센터
Materials Science Forum, Vol.426-4, 2599-2604, 2003
How to select induction surface hardening and finished grinding conditions in order to ensure high compressive residual stresses on machine parts surface
Induction surface hardening creates very desirable residual stresses in hardened surface layer. Residual stresses are always of compressive nature and are usually present to the depth of the induction-hardened layer. Very important are the existence of compressive residual stresses in the longitudinal and tangential direction, i.e. into the depth of the hardened layer. Under different grinding conditions, different temperature profiles were obtained in the thin surface layer which has effected microstructural changes and changes in the microhardness and residual stress profiles. Manufacturing engineers are often confronted with the:question of how to achieve this kind of residual stress profile. It should be emphasized here that because of their lower heat conductivity alloyed steels for surface hardening are very difficult to treat and it is difficult to ensure desirable residual stresses in the transition area. That is why special alloyed steels are available that in this respect display a more favourable behaviour in heating and quenching. It is due to these difficulties that delamination of the surface to the very core may occur. By right selection of grinding wheel and grinding conditions taking into accounts physical and mechanical properties of the workpiece material will be kept back very favourabe compressive residual stresses in the hardened surface layer.