1.5MW风力发电机塔架高强连接螺栓断裂研究

Cracking study on high-strength bolt of tubular tower of 1.5 MW wind turbine generator

某1.5 MW风力发电机在运行过程中发生基础环与塔架第一塔节高强连接螺栓断裂失效。利用宏观分析、化学成分分析、力学性能检测、显微组织检测及SEM断口微区分析等试验方法,对断裂的塔架高强连接螺栓进行分析。结果表明:高强螺栓的螺纹根部退刀槽处在脱碳层形成的组织应力及表层材料氢脆的作用下形成沿晶开裂的微裂纹;在风机运行过程中风力冲击载荷、风叶转动产生的冲击载荷及轴向拉应力载荷的叠加作用下,退刀槽处的氢脆微裂纹快速扩展直至整体断裂失效。最后,提出在制造过程中的酸洗工艺后应彻底清理螺栓表面沉积的酸性介质;调质热处理阶段应严格控制热处理炉的碳势等防控措施。

A high strength bolt connecting the base ring with the first tower segment of 1.5 MW wind turbine was broken when the wind turbine was running.The failed bolt was studied by macroscopic examination,chemical composition analysis,mechanical tests test,metallography,fractography,etc.The results show that intergranular microcracks formed in the bolt root relief groove under the action of decarbonization layer microstructure stress and the hydrogen embrittlement of the surface material;under the superposition of the wind shock load,the blade rotation shock load and the axial tensile stress load,the such hydrogen embrittlement microcracks in the relief groove propagated rapidly until the whole fractured and failed.Finally,corresponding suggestions are proposed,such as completely cleaning out the acid after pickling,and strictly carbon potential controlling during heat treatment.