45号钢微动疲劳门坎值特性研究

Research on 45-carbon steel fretting fatigue damage threshold properties

通过中断性试验研究了45号钢的微动疲劳门坎值,并对不同微动次数下接触面的裂纹特征进行了观察.试验测得45号钢显著存在一个微动疲劳门坎值,微动次数直至超过微动疲劳门坎值时,微动才会使试样疲劳寿命显著下降.以试样上预定的微动循环次数与全微动下试样疲劳基准寿命的比值表示,其微动疲劳门坎值大约在20%～40%范围内.改变载荷条件,该门坎值仍保持在20%～40%范围内;显微观察显示,在微动循环次数超过门坎值之后,在接触磨损面上几乎都能观察到明显的大裂纹.

The fretting fatigue damage threshold studies were conducted on 45-carbon steel through interrupted fretting fatigue tests, and the relationship between the contact surface crack characteristics and the number of fretting wear cycles was also investigated. There exists a fretting fatigue damage threshold on 45-carbon steel, when the number of fretting wear cycles is over the threshold value cycles, the fatigue life of the specimen will be decreased significantly. The damage levels were calculated as a percentage of the total cycles with fretting for 100% of its life to fracture for the baseline fretting fatigue specimen. The value of the threshold is in the range of 20% -40%. The threshold value remains the unchanged with changing the conditions of the load on specimens. Microscopic observation shows that there were obvious long cracks on the contact surface when the fretting cycles were more than the threshold value.