合金元素Cr对粉末冶金凸轮材料摩擦学特性的影响

Effect of Cr Content on Tribological Behavior of P/M Cam Materials

研究了不同Cr含量对3种状态下(烧结态、高频淬火和激光表面淬火)的粉末冶金凸轮材料的密度、硬度以及摩擦磨损特性的影响。研究结果表明,不同Cr含量的铁基粉末冶金凸轮材料经高频淬火和激光表面淬火后,材料的表面硬度和耐磨性得到了明显的提高,激光表面淬火比高频淬火提高得更多;随着Cr含量的增加,硬化层的硬度和深度都有所增加;随着Cr含量的增加,凸轮材料的磨损率和摩擦系数曲线均表现为先降后升,含Cr量1·0%(质量分数)处为最低点;随着Cr含量的增加,材料由马氏体+下贝氏体的复相组织逐渐变为单相马氏体组织,具有强韧性搭配的复相组织在较高载荷下表现出更好的耐磨性。

The effect of Cr content on the density, hardness, friction and wear behaviors of powder metallurgy （P/M） cam materials under three states （ sintered, high-frequency induction quenched and laser surface hardened） were systematically studied. The experimental results show that surface hardness and wear resistance of Fe matrix P/M cam materials with different Cr content are obviously improved after laser surface hardening more than high-frequency induction quenching. With the increasing of Cr content, the hardness and depth of hardened layer are increased. Wear rate and friction coefficient curves of the cam materials have a nadir at Cr content of 1.0% with the change of Cr content. With the increasing of Cr content, the microstructure of the materials is gradually changed from martensite/bainite duplex microstructure to martensite single microstructure. Martensite/bainite duplex microstructure exhibits better wear resistance because it has more reasonable combination of hard and soft phase.