激光选区熔化成形TC4钛合金薄壁件变形与残余应力

增材制造(3-D打印)作为一种近净成形技术,为钛合金薄壁件高质量毛坯制造提供了新途径,但在薄壁件成形过程中产生的变形与残余应力会影响试件的成形质量与后续加工。为了解决这一问题,采用激光选区熔化成形TC4钛合金薄壁件,研究了激光功率、扫描速率、薄壁厚度和扫描路径方向对试件变形与残余应力的影响,测量了试件不同深度的表面残余应力。结果表明,变形主要在薄壁件顶层两侧,最大残余应力主要分布在试件底层与薄壁件中间;当激光功率为180W、扫描速率为1200mm/s时,试件变形最小;当壁厚为0.6mm、扫描路径方向45°时,试件残余应力最小;薄壁件的未处理表面残余应力大于内层表面残余应力。该研究为钛合金薄壁高质量毛坯制造提供了技术帮助。

Deformation and residual stress of TC4 titanium alloy thin-wall parts by selective laser melting

Additive manufacturing (3-D printing) is a near-net forming technology. It provides a new way for manufacturing high quality blanks of thin-wall titanium alloy parts. However, in the forming process of thin-wall parts, deformation and residual stress will affect forming quality and subsequent processing of the specimens. In order to solve this problem, TC4 titanium alloy thin-wall parts were formed by selective laser melting. The effects of laser power, scanning speed, thickness of thin-wall and direction of scanning path on deformation and residual stress of specimens were studied. Surface residual stresses at different depths were measured. The results show that deformation occurs mainly on both sides of the top layer of thin-wall parts. The maximum residual stress is mainly distributed in the bottom and the middle of thin walls. With laser power of 180W and scanning speed of 1200mm/s, the deformation of specimen is the smallest. With wall thickness of 0.6mm and scanning path direction of 45°, residual stress of the specimen is the smallest. Residual stress of the untreated surface of thin-walled parts is larger than that of the inner surface. This research provides technical assistance for the manufacture of high quality thin-wall titanium alloy blanks.