EFFECT OF W AND Re ON DEFORMATION AND RECRYSTALLIZATION OF SOLUTION HEAT TREATED Ni-BASED SINGLE CRYSTAL SUPERALLOYS
PU Sheng1, 2, XIE Guang2, 3, ZHENG Wei2, WANG Dong2, 3, LU Yuzhang2, LOU Langhong2, FENG Qiang1
1 State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083; 2 Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016; 3 Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016
Abstract：Ni-based single crystal superalloys have been widely used for blades and vanes in gas turbine. However, recrystallization (RX) induced by residual strain has been a serious problem for the application of single crystal superalloys. In previous work, effect of microstructure, such as ϒ', g/g' eutectics and carbides, as well as heat treatment parameters, on the RX behavior have been studied. However, the effect of alloy elements on the RX behavior has rarely been reported. Therefore, in this work, the effect of the important solution strengthening elements, W and Re, on the deformation and RX of solution heat treated Ni-based single crystal superalloys was investigated. At first, two single crystal superalloys were prepared, and W and Re were added into one alloy among them. After solution heat treatment, these two single crystal superalloys were deformed by shot-peening or Brinell indentation. Then these deformed samples were heat treated to observe the microstructure of RX. It indicated that RX depth decreased with the addition of W and Re irrespective of deformation mode and heat treatment temperature. Short time heat treatment experiment of indented and shot-peened samples both indicated that incubation period of RX was prolonged and nucleation of RX was slowed with the addition of W and Re, which verified that RX was suppressed by W and Re. After shot-peening, micro-hardness of the alloy with W and Re increased, but the depth of deformation zone was obviously reduced. Higher density of dislocation was found in the single crystal superalloy with W and Re, and also lots of dislocation tangles were observed. So, in this alloy, dislocation annihilated slowly, that is, recovery was slowed down, which prolonged the incubation period of RX. During the process of RX grain growth, the maximum RX grain boundary migration velocity was reduced with the addition of W and Re. Moreover, the change of mean RX grain boundary migration velocity showed the same trend with the micro-hardness along the direction of RX depth。
濮晟, 谢光, 郑伟, 王栋, 卢玉章, 楼琅洪, 冯强. W和Re对固溶态镍基单晶高温合金变形和再结晶的影响*[J]. 金属学报, 2015, 51(2): 239-248.
PU Sheng, XIE Guang, ZHENG Wei, WANG Dong, LU Yuzhang, LOU Langhong, FENG Qiang. EFFECT OF W AND Re ON DEFORMATION AND RECRYSTALLIZATION OF SOLUTION HEAT TREATED Ni-BASED SINGLE CRYSTAL SUPERALLOYS. Acta Metall, 2015, 51(2): 239-248.