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

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2017,（11）
• 页码范围: 1300-1307
• 页数: 8页
• 语种: 英文

摘要

The effect of solution annealing on the microstructure and mechanical properties of a Ni-Cr-W-Fe alloy developed for advanced 700 ℃ ultra-supercritical power plants was investigated.Test samples in this study were subjected to different solution treatments and the same aging treatment (at 760 ℃ for 1 h).When solution annealing temperature was elevated from 1020 ℃ to 1150 ℃,the stress-rupture life at 750℃/320MPa was increased from 60h to 300h,the stress-rupture elongation was enhanced from 12％ to 17％,and the elongation of the tensile at 750 ℃ 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.