プラズマ高濃度浸炭による炭化物形態制御と疲れ特性

概要

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Super carburizing is characterized by its high surface carbon content up to 2-4% and carbide dispersion in the case. This process is a promising heat treatment to strengthen case hardened parts, such as gears and bearings. However, it can be predicted that the carbide morphology will change with a difference in the heat cycle, mass and shape of the workpiece.Therefore, the influence of carbide morphology in the case on fatigue properties was investigated. Plasma carburizing was used to disperse carbides in case of new grade steel (0.18% C-0.5% Si-0.3% Mn-2.25% Cr-0.4% Mo). The size and area fraction of the carbides was varied 0.6-1.8μm and 9-40%, respectively. It is confirmed that the carbide morphology has little influence on both the 107 cycle bending fatigue limit and the fatigue strength in the low cycle region.