Effect of Solution Annealing on Microstructure and Mechanical Properties of a Ni-Cr-W-Fe Alloy  

作　　者：Meiqiong Ou Yingche Ma Xianchao Hao Baifang Wan Tian Liang Kui Liu 

机构地区：[1]Institute of Metal Research, ChineseAcademy of Sciences, Shenyang 110016, China [2]School of Materials Science and Engineeringl University of Science and Technology of China, Hefei 230026, China [3]Jiangsu Toland Alloy Co., Ltd. Danyang 212352, China

出　　处：《Journal of Materials Science & Technology》2017年第11期1300-1307,共8页材料科学技术（英文版）

摘　　要：The effect of solution annealing on the microstructure and mechanical properties of a Ni-Cr-W-Fe alloy developed for advanced 700？C ultra-supercritical power plants was investigated. Test samples in this study were subjected to different solution treatments and the same aging treatment（at 760？C for 1 h）.When solution annealing temperature was elevated from 1020？C to 1150？C, the stress-rupture life at750？C/320 MPa was increased from 60 h to 300 h, the stress-rupture elongation was enhanced from12% to 17%, and the elongation of the tensile at 750？C was improved from 11% to 24%. All tensile and stress-rupture samples displayed an intergranular dimple mixed fracture. Intergranular micro-cracks had a great relationship with the morphology of grain boundary carbides. Most carbides retained the morphology of globular shape and continuous thin plate. After tensile and stress-rupture tests, a few carbides were converted into lamellar. The results showed that intergranular micro-cracks were easier to form at continuous thin plate carbides than at globular shape carbides. Lamellar carbides hardly caused the nucleation of micro-cracks. Besides, grain boundaries sliding and elements diffusion during stressrupture tests led to the formation of precipitate free zones, which accelerated the extension of microcracks and influenced the stress-rupture life.The effect of solution annealing on the microstructure and mechanical properties of a Ni-Cr-W-Fe alloy developed for advanced 700？C ultra-supercritical power plants was investigated. Test samples in this study were subjected to different solution treatments and the same aging treatment（at 760？C for 1 h）.When solution annealing temperature was elevated from 1020？C to 1150？C, the stress-rupture life at750？C/320 MPa was increased from 60 h to 300 h, the stress-rupture elongation was enhanced from12% to 17%, and the elongation of the tensile at 750？C was improved from 11% to 24%. All tensile and stress-rupture samples displayed an intergranular dimple mixed fracture. Intergranular micro-cracks had a great relationship with the morphology of grain boundary carbides. Most carbides retained the morphology of globular shape and continuous thin plate. After tensile and stress-rupture tests, a few carbides were converted into lamellar. The results showed that intergranular micro-cracks were easier to form at continuous thin plate carbides than at globular shape carbides. Lamellar carbides hardly caused the nucleation of micro-cracks. Besides, grain boundaries sliding and elements diffusion during stressrupture tests led to the formation of precipitate free zones, which accelerated the extension of microcracks and influenced the stress-rupture life.

关 键 词：Ni-Cr-W-Fe alloy Solution annealing Grain boundaries carbides Precipitate free zones Mechanical properties 

分 类 号：TG146.15[一般工业技术—材料科学与工程] TG166[金属学及工艺—金属材料]