60Si_2Mn钢的低周拉扭复合微动疲劳特性

测量60Si_2Mn钢在拉扭复合载荷作用下的低周微动疲劳特性,研究了不同轴向循环拉伸应力幅值对微动疲劳寿命、循环软化特性以及摩擦磨损表面和断口形貌的影响.结果表明,随着循环拉伸应力幅值的提高,60Si_2Mn钢的微动疲劳寿命降低幅度不同,发生循环软化的时期不断提前,完成循环软化的疲劳周期也不断缩短。同时,微动摩擦副产生的氧化物磨屑对微动磨损性能有重要影响,在疲劳前期加剧摩擦磨损,在疲劳后期减轻摩擦磨损。微动疲劳裂纹源形成于试样发生微动摩擦磨损的表面,并出现疲劳台阶。在扭矩产生的切向剪切应力作用下,疲劳裂纹沿着与轴向45°角的方向扩展,最终在断口上留下显著的舌状凸起,拉应力的幅值越大舌状凸起越明显。

The Low Cycle Tensile-torsion Fretting Fatigue Properties of 60Si_2Mn Steel

The low cycle fretting fatigue properties of 60Si2Mn were investigated in the condition of tensile-torsion multi-axial loading. The results showed that the tensile stress amplitude affect the fretting fatigue performance significantly. With the tensile stress amplitude increasing, the fretting fatigue life reduced nonlinearly, and the cycle softening occurred earlier and completed in less cycles. Oxide wear debris generated on the fretting wear scars have a significant impact on fretting fatigue, which exacerbated fretting wear in the early-stage of fatigue, and eased the wear later. Fretting fatigue crack initialed on the fretting wear scars, propagated along 45^o  angle to the axial direction at the existence of tangential shear stress, and eventually left tongue shape protrusion significantly at fracture. The greater the tensile stress amplitude, the bigger the tongue protrusion.