钛合金GTAW焊接温度场对焊缝微观组织影响研究  

Study on the influence of GTAW welding temperature field on the microstructure of titanium alloys welded joints

作　　者：龚亚 张玉佳 张林[1] 周苏婷 芦丽莉[1] 付超 丁涛 陈浩瀚 GONG Ya;ZHANG Yujia;ZHANG Lin;ZHOU Suting;LU Lili;FU Chao;DING Tao;CHEN Haohan(Nuclear Power Institute of China,Chengdu 610213,Sichuan,China)

机构地区：[1]中国核动力研究设计院,四川成都610213

出　　处：《金属加工（热加工）》2024年第12期18-29,共12页MW Metal Forming

摘　　要：及近α钛合金具有比强度高、耐蚀性优异等特点,因此被广泛应用于船舶、航空航天及原子能等诸多领域。在钛合金的焊接过程中,焊接温度场对焊接接头的微观组织具有显著影响,进而影响到构件的力学性能。采用钨极惰性气体保护焊(GTAW)制备了Ti-2Al-2.5Zr和Ti-4Al-2V钛合金的对接焊缝,对其焊接过程进行了温度场仿真,并进行了焊缝截面的微观组织表征及晶粒取向分析。结果表明:采用分区焊接工艺调节可获得分布较均匀的温度场,在β相变温度时,各特征位置冷却速率大小受热传递影响呈现一定顺序。从热影响区到熔合区,焊缝组织形貌由等轴晶过渡到针状α相及α片层,晶体呈现出一定程度的变体选择,倾向于向60°/[11-20]、60.83°/[-1.377-12.3770.359]两类变体转变。β→α相变时,冷却速率较低位置的60°/[11-20]和60.83°/[-1.377-12.3770.359]两种变体减少,63.26°/[-1055-3]类变体增多。焊缝织构类型主要为{0001}<10-10>及{10-10}<11-20>两类板织构。本研究对提高钛合金焊接结构的可靠性,以及为钛合金在高端装备制造领域的进一步应用提供了科学依据。αand near-αtitanium alloys possess various good characteristics,including high specific strength,corrosion resistance ect.and are extensively utilized in many fields such as shipbuilding,aerospace,and atomic energy.The temperature field during titanium alloy welding significantly influences the microstructure of the welded joint,therefore affecting the mechanical properties of the component.In this paper,Gas Tungsten Arc Welding process(GTAW)was used to fabricate the butt joints of Ti-2Al-2.5Zr and Ti-4Al-2V alloys.The temperature field simulation of the welding process and the microstructure characterization and grain orientation analysis of the weld section were carried out.The results indicate that using zone welding process adjustment can obtain a relatively uniform temperature field.During theβphase transition,the cooling rate at each characteristic position is influenced by thermal transfer,thus exhibiting a certain order.From the Heat-affected zone to the Fusion zone,the microstructure of the weld seam transitions from equiaxed grains to elongatedα'phases andαlayers,and the crystals exhibit a certain degree of variant selection,tending more towards two variant types:60°/[11-20]and 60.83°/[-1.377-123770.359].During theβ→αphase transition,the positions with lower cooling rates showed a decrease in the 60°/[11-20]and 60.83°/[-1.377-12.3770.359]variants,while the 63.26°/[-1055-3]variants increased.The main two types of texture are{0001}<10-10>,and{10-10}<11-20>plate texture.This study provides a scientific basis for improving the reliability of titanium alloy welded structures and the further application of titanium alloys in the field of high-end equipment manufacturing.

关 键 词：钛合金 焊接温度场 微观组织演变 晶粒取向 变体选择 

分 类 号：TG444.74[金属学及工艺—焊接]