Distortion analysis of gears quenched in different cooling gases

摘要

This article presents analysis of the mechanical properties, structure and deformation of gearsafter vacuum carburizing process followed by quenching with gases at high pressure.These case-hardened (to the effective case depth of 0.3 mm and 0.6 mm for the criterion　450HV1) gears of module 2 (16MnCr5) and 5 (15CrNi6) were investigated. The processes were　carried out in temperatures 950℃ and 1000℃. The cooling ratios in nitrogen and helium and　their effects on microstructure, shape and dimensional changes in the characteristic points of the　geometry of gears was compared and analyzed.Moreover, processes were also carried out for layers of thickness 1.2 mm what aimed to investigate the effect of case depth layer thickness on the deformation with the invariant other parameters of heat treatment.On the basis of research results, the basic relations between the temperature of the process,carburized layer thickness, the type of cooling medium and their influence on the volume gears　deformation after heat treatment processes were determined. These results were compared with　the results of heat treatments realized with oil quenching with vigorous agitation.