微視組織に及ぼす微粒子衝突処理の影響

抄録

In this study, fine particle bombarding treatment (FPB) was applied to SCM435 chromium molybdenum steel and A5052 aluminum alloy. The effects of various FPB conditions on mechanical properties and microstructures were examined. In the result, the grain refinement layer observed, the maximum thicknesses were respectively about 30μm for SCM435 and about 15μm for A5052 in sufficiently bombarding. In this layer, two types of microstructures were formed, the ultrafine grained microstructures, and the lamellar structures. In the ultrafine grained microstructures grains were refined into the size of several hundred nanometers. On the other hand lamellar structures involved fragments of shot materials and the grain size was several ten nanometers. The ultrafine grained microstructures have a lot of dislocations, but the lamellar structures were little. The lamellar structure occupied 50% of the FPB treated surface. In accordance with Hall-Petch relationship, the hardness of the FPB treated surface was increased with grain size.