高强马氏体不锈钢内齿轮裂纹的失效分析

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Failure analysis of cracks in high-strength martensitic stainless steel internal gears

LIXing，HULiming，SHUWenxiang，WANG Chunjian，LUYunxia Beijing Spacecraft Co.，Ltd.，Beijing 10oo90， China

Abstract： The fracture cracks of 9Cr18 stainless steel internal gears were analyzed through chemical composition analysis， mechanical property testing， metallographic structure analysis， macroscopic inspection and SEM morphology observation， withthe nature of the cracks finally determined and the possible cracking causes analyzed. Theresultsshowthatthe internal gearsare treatedbyquenching + low-temperature tempering to a hardness of （60±2） （ HRC，with large structural stressduring the martensitic transformation process，and the material structure is in the state of tempered martensite + carbides at this time.The presence of carbides will significantly reduce the material's crack propagationresistance，greatly increase the britleness of the materialandalso significantly enhance the stress sensitivity of the parts.Coupled withthe stressconcentration parts inherent inthe parts，the abovecomprehensive factors lead to the cracking of the internal gears.The improvement measures are toadd smallround corners at the sharp corners in the structure，and the surface at the transition or sharp corners should not have burrs or protrusions to reduce therisk of stressconcentration，and magnetic particle testing is used to detect surface cracks of the product after heat treatment，so as to ensure that the processed parts are free of cracks through this measure.

Keywords：martensitic; 9Cr18 stainlesssteel; internal gears;crack;failure analysis

1序言

随着我国空间站、深空探测、载人登月及小行星探测等任务的推进，对轻质、高可靠性、高传动精度、长寿命的驱动机构类产品的需求越来越多，尤其是齿轮驱动机构类产品[]。（剩余4738字）