マルエージング鋼の耐摩耗性と疲労限度に及ぼす高温溶体化の影響

抄録

Solution treatments at high temperatures in air were performed on maraging steel to facilitate the reaction between the elements contained in the steel and the atmosphere. The aim was to improve the wear resistance and fatigue limit of the steel by forming a high-hardness layer on its surface. The microscopic properties of maraging steel specimens were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, electron backscatter diffraction, nano-indentation test, and micro-Vickers hardness test. The wear resistance and fatigue properties were examined by ball-on-disc wear and four-point bending fatigue tests, respectively. Solution treatments at high temperatures created oxide layers with pores on the surface of maraging steel. Although this process decreased the hardness inside the steel, aging after the solution treatment improved the hardness reduction. The wear resistance of maraging steel was improved by solution at a high temperature, owing to the formation of an oxygen compound layer. The fatigue limit of maraging steel treated with solution at a high temperature and aging was higher than that of the sample treated with conventional solution and aging. However, the brittle compound layer promoted fatigue crack initiation, which decreased the fatigue limit of the maraging steel.