不同材质的重载齿轮热处理后的疲劳性能研究

Fatigue Property of Heavy Gears of Different Materials After Heat Treating

齿轮是一种普遍使用的传动件,其疲劳性能对机械装备的使用寿命具有极其重要的影响。为了弄清齿轮的材料和热处理工艺对齿轮疲劳性能的影响,分别采用42CrMo、22CrNi2MoNb、20CrMnMo和20CrMnTi钢等4种材料制作了一种推土机用重载齿轮,并进行了不同工艺的热处理:42CrMo钢齿轮离子渗氮,渗层深度>0.4 mm;22CrNi2MoNb、20CrMnMo和20CrMnTi钢齿轮渗碳和淬火,渗层深度1.8～2.4 mm。随后检测了齿轮的显微组织和硬度,进行了断口分析,并在120 kN的载荷下进行了疲劳试验。结果表明:经离子渗氮的42CrMo钢齿轮由于渗层较浅,其疲劳性能比渗碳淬火的其余三种钢齿轮差;而三种经渗碳和淬火处理的齿轮中,22CrNi2MoNb钢齿轮由于含碳量稍高,晶粒较细小及强韧性较好,疲劳性能最佳。

Gear is a commonly used transmission part, and its fatigue property will have an extremely important effect on service life of mechanical equipments. In order to identify the effect of materials from which gears are made and heat treating processes on fatigue property of gear, one type of heavy gears for bulldozer were made from four materials such as 42CrMo, 22CrNi2MoNb, 20CrMnMo and 20CrMnTi steels respectively, and the 42CrMo steel gear was ion nitrided to a depth of more than 0.4 mm, and the other three types of gear were carburized to a depth of 1.8 to 2.4 mm then hardened. Subsequently, the gears were subjected to microstructure survey, hardness measurements, fracture analysis, and fatigue tests at a load of 120 kN. The results indicated that the 42CrMo steel gear was inferior to the 22CrNi2MoNb, 20CrMnMo and 20CrMnTi steel gears in fatigue property because of its relatively shallow case, and that 22CrNi2MoNb gear exhibited the best fatigue property because of its slightly higher carbon content, finer grains and better strength and toughness of the three types of gears that were carburized and hardened.