论文部分内容阅读
材料成形过程中,一个备受关注的问题是能否实现在不发生开裂的基础上达到要求的变形。本实验基于热压缩实验(变形温度为1123~1373 K,应变速率为0.01~10 s~(-1),变形量为70%)获得的开裂样本,证实了铸态Ti40合金的主要开裂模式为45°剪切开裂、自由表面纵向开裂和内部三叉晶界沿晶开裂。借助SEM重点分析了变形参数对开裂机制的影响规律,发现在低温1123 K变形时,主要是穿晶解理脆性断裂,1273 K变形时,转变为韧性断裂,高温1373 K变形时,大量的小韧窝被观察到;应变速率对铸态Ti40合金的开裂行为也具有重要影响,在低应变速率0.01 s~(-1)变形时,样本没有发生开裂,在0.1和1 s~(-1)变形时,在开裂表面观察到大量的韧窝,属于韧性开裂,在高应变速率10 s~(-1)变形时,开裂表面呈现脆性开裂特征。最后深入探讨了铸态Ti40合金的损伤机制和开裂原因,绘制了铸态Ti40合金的开裂原理图。
A major concern in the material forming process is the ability to achieve the required deformation without cracking. In this experiment, based on the hot compressing experiment (deformation temperature of 1123 ~ 1373 K, strain rate of 0.01 ~ 10 s ~ (-1), deformation of 70%) obtained cracking samples, confirmed the as-cast Ti40 alloy cracking mode 45 ° shear cracking, free surface longitudinal cracking and intergranular intergranular cracking. The influence of deformation parameters on the cracking mechanism was analyzed by SEM. It was found that the brittle fracture was mainly transgranular cleavage at 1123 K and the ductile fracture at 1273 K, and the deformation was small at 1373 K The dimples were also observed. The strain rate also had an important effect on the cracking behavior of as-cast Ti40 alloy. At low deformation rate of 0.01 s ~ (-1), the samples did not crack. At 0.1 and 1 s ~ (-1) Deformation, a large number of dimples were observed on the cracked surface, which belonged to ductile cracking. At the high strain rate of 10 s ~ (-1), the cracked surface showed brittle cracking. Finally, the damage mechanism and cracking reason of as-cast Ti40 alloy were discussed in depth, and the cracking principle diagram of as-cast Ti40 alloy was drawn.