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一前言接触疲劳是轴承、齿轮等机械零件的失效形式,它是在压应力周期性的循环作用下形成的一种表面剥落损坏。根据材料的热处理和表面强化处理工艺不同、显微组织的差异、试样和试验条件不同,疲劳源可以在试样表面或次表层(试样内部)形成。这种破损具有疲劳源的萌生、疲劳裂纹的扩展和最终断裂三个过程。目前接触疲劳试验没有统一标准,要建立试验标准,除了统一试样标准和试验方法外,还需对影响接触疲劳寿命的其它因素和破损机理进行研究。本次试验采用淬火+低温回火的GCr15钢,观察试样失效后表面剥落坑的断口形态,疲劳源的形成部位、疲劳裂纹中主裂纹、次生裂纹的形态和在金相组织中的扩展途径。并从断口形态和疲劳裂纹扩展方式二方面来分析和探讨剥落坑的形成机理。
Preface Contact fatigue is the failure form of mechanical parts such as bearings and gears. It is a kind of surface spalling damage caused by the cyclic circulation of compressive stress. According to the material heat treatment and surface hardening process, the microstructure difference, the sample and the test condition are different, the fatigue source can be formed on the sample surface or subsurface (sample interior). This damage has the source of fatigue initiation, fatigue crack growth and final fracture of the three processes. At present, there is no uniform standard for contact fatigue test. To establish the test standard, besides the unified test standards and test methods, other factors that affect the contact fatigue life and the damage mechanism need to be studied. In this experiment, GCr15 steel with quenching and lowtemperature tempering was used to observe the fracture morphology of the surface peeling pits after fatigue failure, the formation site of the fatigue source, the morphology of the primary cracks and secondary cracks in the fatigue crack, and the expansion in the microstructure way. And from the fracture morphology and fatigue crack growth mode to analyze and explore the formation mechanism of peel pits.