置氢对钛合金激光焊接接头超塑变形均匀性的影响

采用置氢处理的方法提高TC4钛合金激光焊接接头的超塑性变形均匀性,并提出表征不均匀性系数K进行定量表征.结果表明,当置氢量超过0.29%时,随着含氢量的升高,钛合金焊接板的超塑性能降低,即峰值流动应力增加、截面收缩率降低.但接头的超塑性变形均匀性增加;随置氢量的升高,母材截面收缩率下降幅度大于焊缝截面收缩率下降幅度.变形不均匀系数K可以表征置氢TC4激光焊接接头超塑性变形过程中焊缝与母材变形不均匀性. K值随着含氢量的增大、变形温度的升高以及应变速率的降低而增大. K值在含氢量1.299%,变形温度920℃,应变速率10-4 s-1时达到最大0.84.

Effect of hydrogenation on uniformity of superplastic deformation of titanium alloy laser weld

Hydrogenation can improve the uniformity of superplastic deformation of TC4 titanium alloy laser weld. The non-uniform deformation coefficient K was introduced to quantitatively characterize the non-uniform deformation. The results indicate that when the hydrogen content exceeded 0.2%, the super plastic property of welded joint degraded with the increase of hydrogen, with increase of peak flow stress and decrease of percentage reduction in area, but the uniformity of superplastic deformation increased. With the increasing of hydrogen content, the percentage reduction in area of base metal decreased more than that of welded joint. The non-uniform deformation coefficient K can characterize the non-uniform deformation of the titanium alloy laser weld and base materials with hydrogenation during superplastic deformation. The K value increased with the increase of hydrogen content, the increase of temperature, and the decrease of strain rate. The K value reached the maximum value 0.84 when the hydrogen content was 1.299%, the deformation temperature was 920℃, and the strain rate was 10-4s-1.