800kW风力发电机变速箱输出轴断裂失效分析

Fracture failure analysis on gearbox output shaft of 800 kW wind turbine generator

800 kW风力发电机变速箱输出轴服役6天后发生断裂,通过对断轴进行材质分析、断口分析、金相分析、力学性能试验,以及材料组织模拟与性能检测等研究,分析其断裂失效的原因。结果表明,输出轴的断裂属于早期扭转多源疲劳断裂。断裂源为输出轴R角位置上分布着由于表面处理工艺不当而产生的大小不一的凹坑;输出轴表层存在的过热组织和不均匀硬化层,导致输出轴在高速运行过程中加速疲劳裂纹的萌生和扩展;心部组织较严重的偏析现象对输出轴的疲劳断裂起了促进作用。

The gearbox output shaft of the 800 kW wind turbine generator occured fracture after 6 days services. By use of chemical analysis, fractography, metallographie examination, mechanical properties test, simulation and performance test of coarse grain area, the reason of fracture was researched. The results indicate that the fracture of the output shaft is multi-sources torsional fatigue fracture and the fracture sources are those many concave hollows with various size results in improper surface treatment process, which locate on the round angle. In the meanwhile, the overheated structure defect （coarse grains） and uneven hardened layer accelerate the initiation and propagation of the fatigue crack, which is further promoted by the severe microstrueture segregation in the core of the output shaft.