利用电子背散射衍射技术, 对激光立体成形GH4169镍基高温合金沉积态试样以及1100 ℃保温5和30 min水淬后试样的显微组织、晶界特点和晶体取向等进行了分析. 结果表明, 再结晶过程中随晶粒尺寸得到细化的同时, 各晶粒的晶体取向逐渐变得随机, 消除了沉积态材料中原本存在的各向异性, 合金的界面特点也发生变化, 大角度晶界数量逐渐增多, 且再结晶后期<111>60°孪晶界大量出现, 占总界面体积分数的44%, 孪晶的形成对激光立体成形GH4169合金的晶粒细化起了很重要的作用; 再结晶形核机制在再结晶初期以原始晶界的亚晶形核和晶界弓出机制为主, 孪晶相关的晶粒细化机制是再结晶后期晶粒细化的重要机制.

The dynamic-load mechanical of laser solid forming (LSF) GH4l69 Ni-based superalloy is influenced by the coarse columnar grains formed in LSF processing and then its application in jet engines like turbine disks is limited. The previous study showed that the grain structure of the LSF GH4l69 superalloy can be refined by recrystallization processing during post heat treatment. In this work, the microstructure, interface and crystal orientation of the as-deposited and heat treated LSF GH4169 superalloy samples were investigated by EBSD analysis. It was found that the crystal orientations of grains become more randomly organized as the grain structure of the LSF GH4169 superalloy was refined by heat treatment and the holding time of heat treatment was increased. Subsequently, microstructural anisotropy existed in the as-deposited samples was disappeared in the heat treated samples and the fraction of high angle grain boundary was increased greatly. < 111> 60° twin crystal boundary was presented during the later period of recrystallization and the volume fraction of the twin crystal boundary reached up to 44%. This indicated that the formation of twin crystal boundary during static recrystallization of LSF GH4169 samples played an important role in the refinement of grain structure. Sub-grain and grain-boundary migration nucleation were the main nucleation mechanisms at the beginning of the recrystallization and nucleation related to twin was one of the most important mechanisms in the later period of the recrystallization.