Effect of impurities on the creep behavior of centrifugally cast 25Cr-35Ni-Nb alloy
This paper describes the effect of impurities on the creep and stress rupture behavior at high temperature of a centrifugally cast 25Cr-35Ni-Nb alloy which is widely used as furnace tubes in ethylene pyrolysis and reformer furnace.Stress rupture tests were conducted at the temperature of 1100 ℃ and the constant stress of 17 MPa in air.Microstructural features of the 25Cr-35Ni-Nb alloy with impurities addition have been investigated by field emission gun scanning electron microscopy (FEG-SEM) equipped with an Oxford INCA energy dispersive X-ray spectrometer (EDS).The results showed that impurities including S, Pb and Bi had a seriously detrimental effect on creep performance.Microstructural observation results indicated that the grain boundary segregations of S, Pb and Bi took place at the temperature of 1100 ℃.The presence of impurities caused increased amounts of grain boundary voids and microcracks which resulted in premature failure.The results were consistent with those obtained for superalloys.The recent developments in the understanding of mechanisms of creep deformation and fracture of centrifugally cast 25Cr-35Ni-Nb alloy had been also discussed.
25Cr-35Ni-Nb alloy Creep Segregation Impurity S Pb Bi
Tao Chen Xuedong Chen Xiaoming Lian Chunjiao Liu Jiafan Sun
National Engineering & Technical Research Center on Pressure Vessels and Piping Safety,Hefei General Machinery Research Institute Hefei 230031,China
国际会议
2015 International Symposium on Structural Integrity(2015年国际结构完整性学术会议)
沈阳
英文
37-42
2015-05-16（万方平台首次上网日期，不代表论文的发表时间）