整体预热对TNM合金电子束焊接接头组织的影响  

Effect of Overall Preheating on Microstructure of Electron Beam Welded Joint of TNM Alloy

作　　者：贾国钊 付鹏飞 毛智勇 林博超 李立航 杨洋 李嘉文 JIA Guozhao;FU Pengfei;MAO Zhiyong;LIN Bochao;LI Lihang;YANG Yang;LI Jiawen(Science and Technology on Power Beam Processes Laboratory,VIC Manufacturing Technology Institute,Beijing 100024,China)

机构地区：[1]中国航空制造技术研究院高能束流加工技术重点实验室,北京100024

出　　处：《真空科学与技术学报》2023年第6期481-486,共6页Chinese Journal of Vacuum Science and Technology

摘　　要：为抑制发动机TiAl合金新材料的焊接裂纹、改善接头组织,采用整体预热的方式在300℃和500℃恒温环境下,对TNM(Ti-43.5Al-4Nb-1Mo-0.1B)合金试板进行电子束焊接工艺试验,利用光学显微镜(OM)、扫描电镜(SEM)及电子背散射衍射(EBSD)等方法对焊接接头显微组织进行表征,分析了预热温度对焊接裂纹、焊缝形貌、晶粒尺寸、相组成以及硬度等的影响。结果表明,随着预热温度的升高,焊缝宽度有所增加,并且裂纹在预热温度为500℃时消失;靠近焊缝侧的热影响区晶粒明显长大,而远离焊缝侧的热影响区晶粒出现细化;当预热温度升高,焊缝组织中α_(2)相含量减少,γ相含量增加,预热温度为500℃时,γ相含量增加至85.5%,成为焊接接头的主相,同时α_(2)相的类片层状特征消失;通过提升预热温度,TNM合金焊缝位错密度和硬度有明显降低。In order to suppress the welding crack of TiAl alloy for aero engines,the electron beam welding test on TNM(Ti-43.5Al-4Nb-1Mo-0.1B)alloy test plate was carried out at 300℃and 500℃under overall preheating.The microstructure of the joint was characterized by optical microscopy(OM),scanning electron microscopy(SEM)and electron backscattering diffraction(EBSD),and the effects of preheating temperature on the microstructure such as cracks,weld morphology,grain size,phase composition and hardness were analyzed.The results show that the weld width increases with the preheating temperature,and the crack disappears when the preheating temperature is 500℃.Grain coarsening in the near-heat affected zone and refinement in the far-heat affected zone were observed.With increasing preheating temperature,the content ofα_(2)phase decreased and the content ofγphase increased in the welded joint,γphase became the main phase under the preheating temperature of 500℃.In addition,the nearly lamellar feature ofα_(2)phase disappears under the preheating temperature of 500℃.With increasing preheating temperature,the dislocation density and hardness of the weld are obviously reduced.

关 键 词：TNM合金 真空电子束焊接 整体预热 显微组织 

分 类 号：TG456.3[金属学及工艺—焊接]