工艺参数对7075铝合金室温等通道转角拉伸载荷的影响

Effect of process parameters on room temperature equal channel angular drawing load of 7075 aluminum alloy

为探讨拉伸载荷在等通道转角拉伸过程中的变化规律,以7075铝合金为研究对象,基于上限法推导圆柱试样等通道转角拉伸峰值载荷的解析式;利用载荷测量系统分析了7075铝合金拉伸载荷的分布特征,揭示了工艺参数对拉伸载荷变化和各阶段拉伸载荷峰值的影响。结果表明,等通道转角拉伸理论计算峰值载荷与实验峰值载荷的相对误差在10%以内,表明解析式具有较高的可信度;等通道转角拉伸载荷经历了弹性阶段(Ta)、屈服阶段(Tb)、稳定阶段(Tc)和卸荷阶段(Td),其中峰值载荷出现在弹性阶段的末尾;峰值载荷随着模具内角和外角的增大出现下降的趋势,但下降的幅度有所放缓;峰值载荷随着拉伸道次的增加而减小;拉伸路径对峰值载荷影响的顺序为路径C>路径B>路径A,并且第2道次的路径B在拉伸时会出现载荷失稳现象;高速拉伸对拉伸峰值载荷的影响不大,但在低速拉伸时拉伸载荷曲线会出现“爬行”抖动现象。

To explore the variation laws of drawing load during equal channel angular drawing process,taking 7075 aluminum alloy as the research object,and the analytical formula for the peak drawing load of equal channel angular drawing of cylindrical specimens was derived based on the upper limit method;the distribution characteristics of 7075 aluminum alloy drawing load were analyzed using the load measurement system,and the influence of process parameters on the variation of drawing load and the peak drawing load at each stage was revealed.The results show that the relative error between the theoretically calculated peak load of equal channel angular drawing and the experimental peak load is within 10%,indicating that the analytical formula has high reliability;the equal channel angular drawing load goes through the elastic stage(Ta),yield stage(Tb),stable stage(Tc)and unloading stage(Td),with the peak load appearing at the end of the elastic stage;the peak load shows decreasing trend with the increase of the inner and outer angles of the mold,but the decreasing range slows down;the peak load decreases with the increase of drawing passes;the influencing order of drawing path on the peak load is path C>path B>path A,and load instability phenomenon occurs during drawing in the second pass of path B;high speed drawing has little influence on the peak drawing load,but the drawing load curves exhibit phenomenon of“crawling”and shaking during drawing with low speed.