By means of macroscopic analysis,electron microscope and metallographic microscope analysis,the samples of SUP9 stability bar failed in bench test are sampled and analyzed.The results show that the crack source of the fracture sur-face of SUP9 stabilizer bar is located in the inner side of the corner of the stabilizer bar.The crack source is at the local edge of the sample,and there is an obvious indentation on the outer surface of the crack source.A few micro-cracks were found at the bottom of the pit,and the depth of the micro-cracks is about 20-200 μm.No non-metallic inclusions and decarburization are found in the vicinity of the crack after corrosion,and obvious microstructure rheology is observed in the micro-crack,which indicates that the failure of SUP9 rod was not related to the material itself,after heat treatment,the local surface of the stabilizing rod is compressed and deformed by external force,and the stress concentration forms the crack source during the bench test,which results in the fracture failure of the stabilizing rod.
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