风能发电机组叶片连接高强度螺栓断裂失效分析

Fracture Failure Analysis of High Strength Bolts Connecting Blades of Wind Turbine Generator systems

针对风能发电机组用于连接叶片与整机轮毂的螺栓大量断裂的现象,采用断口宏观形貌、化学成分、力学性能测试、金相组织、断口微观形貌分析重点研究螺栓断裂原因。结果表明:螺栓沿轧制方向的金相组织为带状分布的回火索氏体及细小块状铁素体,带状组织的各向异性是力学性能下降、点腐蚀易于发生的主要原因;裂纹起源于螺纹根部的点腐蚀位置,在运行过程受到交变载荷而在应力集中最为严重的螺纹根部发生疲劳断裂。

Because large number of bolts used to connect the blade and the hub of the whole machine are broken,the reasons for the fracture were mainly studied by analyzing the macroscopic morphology of the fracture, chemical composition, mechanical properties test, metallographic structure, and microscopic fracture of the fracture. The results show that the metallographic structure of the bolt along the rolling direction is tempered sorbite and fine block ferrite in a banded distribution, and the anisotropy of the banded structure is the main reason for the decline of mechanical properties and the easy occurrence of pitting corrosion. The crack originates from the pitting corrosion position at the root of the thread,and the fatigue fracture occurs at the root of the thread where the stress concentration is the most serious due to alternating loads during operation.