Ti-23Al-17Nb激光焊接接头的组织性能研究

通过室温和高温拉伸性能测试研究焊后热处理和同步预热对Ti-23Al-17Nb(原子分数,下同)合金CO_2激光焊接接头性能的影响.结果表明,接头室温和高温拉伸性能低,焊后真空热处理提高接头室温和高温拉伸性能,仍低于母材;同步预热接头室温强度和塑性与母材相当,高温强度与焊后热处理效果相当.组织分析显示,焊缝存在两个腐蚀衬度区,组织为B2相,热影响区晶粒由熔合线到母材逐渐细化,焊后热处理和同步预热改变β相基体上α2相的析出.

Study on Microstructures and Properties of Laser Welding Ti-23Al-17Nb Joint

The CO_2 laser welding was conducted to investigate the effect of heat treatment post welding (HTPW) and the synchro preheating on joint microstructures and properties of Ti-23Al-17Nb intermetallics. The results reveal that the tension property of joints both at room temperature and at 650 ℃ is low. Vacuum heat treatment post welding at 850 ℃ improves joint tension property at room temperature and high temperature, but it is lower than that of base metal. And synchro preheating results in increase of the room temperature tension property of joints, even to be equal to that of base metal. Moreover, the high temperature tension strength of joints with synchro preheating is lower than that of HTPW joints and the high temperature elongation of joints using synchronic preheating is nearly the same as that of HTPW joints. Ti-23Al-17Nb weld section can be divided into dark and bright corrosion area. The weld microstructure of laser welding Ti-23Al-17Nb intermetallics is mainly B2 phase, and grain size of heat effect zone (HAZ) becomes finer range from fusion line to base metal. There are α2 phase separating out in strip from β phase in phase transformation area of HAZ. HTPW and synchro preheating have effect on α2 phase precipitation.