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Alloy 617B镍基高温合金具有优良的长期高温服役性能,是目前先进超超临界发电技术锅炉管的主要候选材料.结合金相显微镜、扫描电镜、透射电镜等研究了Alloy 617B在750℃这3种应力条件下的持久蠕变行为及变形过程中材料的组织演化.研究结果表明,该合金750℃外推105h的蠕变断裂强度可达到约80MPa,蠕变断裂曲线呈典型的三阶段特征;随着应力减小,Alloy 617B合金持久蠕变试样的断口由穿晶向沿晶断裂转变,微裂纹、空洞的数量和尺寸也有所降低;初生M23C6的尺寸随蠕变时间的增长有所粗化,边缘有球化趋势,同时二次M23C6也逐渐增长变粗,分布更加广泛;γ'相在断口附近的分布较少.“,”Alloy 617B is defined as a solid-solution strengthened Ni-base superalloy with excellent long-term high temperature performance, and is also one of the most promising candidate materials for advanced ultra super critical (A-USC) applications, operating with steam target temperatures as high as 700~760℃ and pressures of 35~ 37.5MPa. The present investigation concentrates on linking microstructural evolution of Alloy 617B to the creep deformation characterization at 750℃, by comparing the creep behavior at 3 different stress conditions with experimental data utilizing the optical microscopy (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Results show that the105h creep strength of Alloy 617B at 750℃ reaches 80MPa, and a typical creep curve with distinct primary, secondary, and tertiary creep stages was observed. The fracture surface shows the combined ductile transgranular and intergranular fracture modes; cavities and cracks decreases with lower stress condition and longer rupture time; both the primary and secondary M23C6 carbides experience a growing and coarsening progress, and only limited amount ofγ' was observed.