700℃超超临界机组用617B镍基合金的组织结构和析出相

使用扫描电子显微镜(SEM)和透射电子显微镜(TEM)对比分析了617B镍基合金在750℃持久试样和时效态试样的组织结构和析出相。结果表明:在蠕变和时效过程中在晶内和晶界都析出复杂面心立方结构的M23C6,晶内析出有序立方结构γ′相,前者为多边形或条形,后者为粒状;随着试验时间的延长析出物的颗粒尺寸出现长大的趋势;应力对γ′相的生长影响不明显,但是对晶界碳化物有明显的影响;在长时间应力条件下,M23C6碳化物聚集长大。

Microstructure and mechanical properties of alloy 617B

The microstructure and mechanical properties of alloy 617 B in the process of 5000 h aging at 750 °C were systematically investigated by means of SEM, TEM and mechanical analysis. M23C6 particles were dispersed inside grains and distributed discontinuously along grain boundaries and γ′ phases were situated at intragranular sites in the process of aging. The size of precipitates increased with increasing aging time. Inter- and intra-granular carbide and γ′ phase particles inside grains resulted in the precipitation strengthening of this aged alloy, enhancing the strength and hardness. The aged alloy possessed good stabilities of hardness and strength during aging. An obvious decrease of the toughness of this aged alloy was due to γ′ phase particles limiting plastic deformation to the area nearby grain boundaries, resulting in the occurrence of crack along grain boundaries. Additionally, the intergranular cracks apparently led to a decrease in the toughness for this aged alloy due to carbide particles at grain boundaries. The toughness of this aged alloy was fairly stable possibly due to the unchanged distribution of the precipitates during aging.

镍基合金617B的组织结构与力学性能稳定性

研究了镍基合金617B在700℃下时效10 000 h过程组织结构与力学性能的稳定性。供货态镍基合金617B晶内分布Ti N,晶界分布M_(23)C_6。时效后晶内和晶界析出M_(23)C_6,晶内析出γ'相。整个时效过程合金析出相的分布形态和相组成未发生明显变化,γ'相与基体保持共格关系,硬度和强度保持良好的稳定性,时效10 000 h后的时效态合金仍具有较高韧性。