Ti-15-3合金中短裂纹萌生与扩展的微观机理

利用扫描电镜(SEM)和背散射电子衍射(EBSD)技术研究了Ti-15-3合金中晶粒取向差对短裂纹萌生与扩展的影响.结果表明:在Ti-15-3合金中,98%相邻晶粒之间的取向差大于10°;相邻晶粒中,大的晶粒取向差有利于短裂纹的萌生,小的晶粒取向差有利于短裂纹的扩展;短裂纹的尖端方向与下一个晶粒的滑移带方向夹角大于35°时,裂纹穿过此晶粒时容易发生曲折,走"Z"字形路线;小于35°,裂纹沿着滑移带方向扩展;短裂纹尖端扩展到晶界时,如果裂纹尖端方向与晶界的方向之间的夹角小于35°,裂纹沿晶扩展;大于35°,裂纹穿晶扩展.

Micromechanism of Short Crack Initiation and Propagation in Ti-153 Alloy

Effects of grain misorientation angles on the short crack initiation and propagation in Ti-15-3 alloy were studied by means of electron back scattered diffraction (EBSD) and scanning electronic microscope (SEM). In Ti-15-3 alloy, 98% of misorientation angles between adjacent grains are greater than 10°. Among adjacent grains the big misorientation angles are favorable to short crack initiation, whereas the small ones are favorable to short crack propagation. If the included angle between the orientation of short crack tip and that of slip band of next grain is greater than 35°, the crack is easy to zigzag when passing through the next grain; if the angle is less than 35°, the crack propagates along the orientation slip band. When the short crack tip propagates to reach grain boundary and if the included angle between the orientation of short crack tip and that of grain boundary is less than 35°, the short crack propagates along grain boundary and if the angle is greater than 35°, a transgranular crack propagates.