Effect of Solution Annealing on Microstructure and Mechanical Properties of a Ni-Cr-W-Fe Alloy
Effect of Solution Annealing on Microstructure and Mechanical Properties of a Ni-Cr-W-Fe Alloy
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DOI：
10.1016/j.jmst.2016.06.026
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发表时间：
2017-11
影响因子：
10.9
通讯作者：
Meiqiong Ou;Yingche Ma;Xianchao Hao;B. Wan;Tian Liang;Kui Liu
中科院分区：
文献类型：
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作者：
Meiqiong Ou;Yingche Ma;Xianchao Hao;B. Wan;Tian Liang;Kui Liu
研究了固溶退火对一种用于先进700 °C超超临界电厂的Ni-Cr-W-Fe合金组织和力学性能的影响。本研究中的测试样品经受不同的溶液处理和相同的老化处理（在760 °C下1小时）。当固溶退火温度从1020 °C提高到1150 °C时，750 °C/320 MPa持久寿命从60 h提高到300 h，持久伸长率从12%提高到17%，750 °C拉伸伸长率从11%提高到24%。所有拉伸和持久试样均表现为沿晶韧窝混合断裂。晶界微裂纹的产生与晶界碳化物的形态有很大关系。大部分碳化物保持球状和连续薄板状形貌。拉伸和持久试验后，少量碳化物转变为片层状。结果表明，连续薄板状碳化物比球状碳化物更容易形成沿晶微裂纹。层状碳化物几乎不引起微裂纹的形核。此外，持久试验中晶界滑移和元素扩散导致无析出相区的形成，加速了微裂纹的扩展，影响持久寿命。
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 at 750 °C/320 MPa was increased from 60 h to 300 h, the stress-rupture elongation was enhanced from 12% 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 stress-rupture tests led to the formation of precipitate free zones, which accelerated the extension of micro-cracks and influenced the stress-rupture life.