摘要
采用喷丸引入表层残余应力,分析循环载荷时7075铝合金试样的应力松弛现象,讨论喷丸工艺引入的初始残余应力状态、表层显微硬度和表面粗糙度对疲劳抗性和残余应力松弛的影响。结果表明,喷丸引入的表层残余压应力是提高试样疲劳抗性的主要因素,但表层冷作程度与表面缺口效应对喷丸试样的低周与高周疲劳抗性与残余应力松弛有很大影响。循环应力水平接近高周疲劳极限时,经历高周疲劳残余应力无明显松弛;应力水平接近低周疲劳极限时,残余应力发生早期大幅松弛,且残余应力峰外移。
The effect of shot peening trea^nents on the cyclic loading fatigue of 7075 A1 alloy was studied by X-ray diffraction measurements to analyze the impacts of initial residual stress state, surface microhardness and surface roughness on fatigue performance and residual stress relief. The improvement of aluminum alloy specimens＇ fatigue resistance can attribute to the compressive residual stress field in the surface layers. The results show that no significant residual stress relief occurs under the load level corresponding to the fatigue endurance at 4 × 10s cycles. Large residual stress relief occurs at an early stage under the load level corresponding to the fatigue endurance at 5 × 104 cycles. Accordingly, the residual peak stress moves outside from the surface layers. Surface cold work by shot peening impacts and surface notch effect exerted by roughness dimples can provide great influences to fatigue performance at low or high cycles as well as to residual stress relief.
出处
《热加工工艺》
CSCD
北大核心
2013年第14期27-30,33,共5页
Hot Working Technology
基金
广西自然科学基金项目(2012GXNSFBA053150)
