Ti-3Al-5Mo-4.5V钛合金棒材冷镦性能及表面微裂纹的研究

Study on the Lateral Surface Microcracks and Cold Upsetting Performance of the Ti-3Al-5Mo-4.5V Titanium Alloy Bar

摘要:

通过冷镦实验和扫描电镜、光学显微镜手段，研究了BT16钛合金棒材表面粗糙度和压缩率对冷镦性能及压缩试样侧表面微裂纹的影响。结果表明：轧制退火态BT16钛合金具有细等轴α+β晶粒组织和良好的冷镦性能。随压缩率和表面粗糙度增加，侧表面微裂纹逐渐增加。当压缩率为75%时，冷镦试样和螺栓侧表面没有任何宏观裂纹，但在高倍电镜下可清楚地观察到侧表面微裂纹，其特征完全区别于一般宏观裂纹。评价了冷镦紧固件表面质量以及表面粗糙度、侧表面微裂纹和压缩率之间的关系。

Abstract:

The influence of surface roughness and compression ratio on the lateral surface microcracks of the compressed specimens of Ti-3Al-5Mo-4.5V titanium alloy (BT16) has been investigated by cold upsetting experiments, scanning electron microscopy (SEM) and optical microscopy (OM). The results show that the rolled and annealed α+β BT16 alloy bars with the finest equiaxed grains have the good cold upsetting performance. With the increasing of compression ratio and surface roughness, the lateral surface microcracks gradually increase. The lateral surface of the cold upsetting specimens and bolts is without macrocracks when the compression ratio reaches 75%, but under high magnification lateral surface microcracks can be distinctly observed, which are entirely different from common macrocracks. Surface quality of cold upsetting fasteners was evaluated and the relation between lateral surface roughness, microcracks and compression ratio was determined in cold upsetting test.