为探明Ti-V-Cr系阻燃钛合金的焊接性能,采用激光焊接对模拟有非贯通裂纹的 Ti-25 V-10 Cr阻燃钛合金薄板进行了焊接修复,较为系统地研究了激光焊接对其微观组织、显微硬度和拉伸性能的影响.结果表明, Ti-25V-10Cr阻燃钛合金焊缝组织为粗大的铸态β柱状晶,在焊缝中心能清晰地看到焊缝两侧β柱状晶相对生长的交界面；热影响区仍为单一β等轴晶,仅近熔合线处晶粒变得粗大；同时,焊缝区的硬度已达约570 HV(为母材硬度的1．78倍),而热影响区的硬度相对于母材则变化不大；此外,焊接接头的拉伸强度约为405 MPa,仅为母材拉伸强度的40％左右,拉伸断裂发生在焊缝中心附近处,并呈现以脆性断裂为主的混合断裂.可见,Ti-25V-10Cr阻燃钛合金的焊接性能将会是制约其进一步广泛应用的主要因素之一.
To explore welding performance of Ti-V-Cr burn-resistant titanium alloy,welding repair of Ti-25V-10Cr burn-resistant titanium alloy sheet with a simulative non-through crack was carried out by adopting laser welding,and effects of laser welding on microstructure,microhardness and tensile property were investigated. Results show that the welding seam microstructure is coarse as-castβcolumnar crystals,and the relative growth interface ofβcolumnar crystals on both sides is visible in welding seam center.The heat-affected zone (HAZ)microstructure remains singleβequiaxed crystals,and only some grains closed to the fusion line is coarsening.Meanwhile,the microhardness of welding seam reaches to about 570 HV that is 1.78-fold of the one of base metal,but the microhardness of HAZ changes a little.Moreover,the tensile strength of welded joint is about 405 MPa that is only 40% or so of base metal.The fracture of the tensile samples occurres near the weld-ing seam center,and the tensile fracture presents a mixed rupture and the brittle rupture is prominent.It can be concluded that the welding performance of Ti-25V-10Cr burn-resistant titanium alloy will be a main restricting factor for its widespread application.
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