The results show that the axle has defects in heat treatment, which leads to micro crack in early stage of service life and the extended crack finally causes fatigue fracture.
结果表明，该轴热处理上存在的不合理之处，导致轴在服役早期出现微裂纹，部分微裂纹在工作应力的作用下疲劳扩展，最终产生疲劳断裂。
The fracture occurres at heat affected zone (HAZ) of most fatigue specimens. This is due to the structure inhomogeneity and the higher hydrogen content of materials at HAZ.
疲劳试样多数断于接头的热影响区，造成这一结果的主要原因是热影响区的组织不均匀性和氢含量相对较高。
The fracture occurres at heat affected zone (HAZ) of most fatigue specimens. This is due to the structure inhomogeneity and the higher hydrogen content of materials at HAZ.
疲劳试样多数断于接头的热影响区，造成这一结果的主要原因是热影响区的组织不均匀性和氢含量相对较高。
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