The effect of rare earth(RE) on Mo partitioning and resultant mechanical and microstructural behavior of a duplex stainless steel during hot working condition was investigated. It was found that RE effect was sensit...The effect of rare earth(RE) on Mo partitioning and resultant mechanical and microstructural behavior of a duplex stainless steel during hot working condition was investigated. It was found that RE effect was sensitive to temperature. At the high temperature, the development of dynamic recovery(DRV) in α phase was slowed down while the dynamic recrystallization(DRX) process in γ phase was accelerated by RE, whereby both work hardening rate(at low strain) and dynamic softening rate(at high strain) increased and moreover, the discrepancy on the hardness of the both phase reduced. Whereas at the low temperature, the effect of RE was opposite as compared with those in the high temperature. Mo partitioning analysis by EPMA indicated that RE enhanced the partitioning of Mo in α phase while reduced Mo concentration in γ phase at higher temperature whereby the mismatch between two phases could be improved indicated by the elimination of voids and cracks at α/γ interface, but it was contrary to that at the low temperature. Mo partitioning was believed to be an important cause for the RE effect on the differences of mechanical and microstructural behavior. Also this result provided a reasonable evidence for micro-alloying of RE in DSSs.展开更多
The effect of rare earth(RE) on creep rupture of economical 21Cr-11Ni-N heat-resistant austenitic steel was investigated at 650 °C under different stress levels. It was found that RE could increase the time to ...The effect of rare earth(RE) on creep rupture of economical 21Cr-11Ni-N heat-resistant austenitic steel was investigated at 650 °C under different stress levels. It was found that RE could increase the time to creep rupture, especially at long-term creep duration. The logarithm of the time to creep rupture(lgtr) was a linear function of the applied stress(σ). RE addition was favorable to generating a high fraction of low-coincidence site lattice(CSL) boundaries which was a possible cause for improving the creep rupture resistance. The fracture surface of RE-added steel exhibited less intergranular cracks suggesting the alteration on the nature of grain boundaries due to the presence of RE. RE addition changed the morphology of the intergranular chromium carbides from continuous network shape to fragmentary distribution which was another cause for longer creep duration. These results strongly suggested that the effect of RE alloying played a crucial role in improving the creep rupture resistance.展开更多
基金supported by the National Natural Science Foundation of China(51101136)Natural Science Foundation of Hebei Province(E2012203013)+1 种基金National High Technology Research and Development of China(863 program,2010AA03A407)College Innovation Team Leader Training Program of Hebei Province(LJRC012)
文摘The effect of rare earth(RE) on Mo partitioning and resultant mechanical and microstructural behavior of a duplex stainless steel during hot working condition was investigated. It was found that RE effect was sensitive to temperature. At the high temperature, the development of dynamic recovery(DRV) in α phase was slowed down while the dynamic recrystallization(DRX) process in γ phase was accelerated by RE, whereby both work hardening rate(at low strain) and dynamic softening rate(at high strain) increased and moreover, the discrepancy on the hardness of the both phase reduced. Whereas at the low temperature, the effect of RE was opposite as compared with those in the high temperature. Mo partitioning analysis by EPMA indicated that RE enhanced the partitioning of Mo in α phase while reduced Mo concentration in γ phase at higher temperature whereby the mismatch between two phases could be improved indicated by the elimination of voids and cracks at α/γ interface, but it was contrary to that at the low temperature. Mo partitioning was believed to be an important cause for the RE effect on the differences of mechanical and microstructural behavior. Also this result provided a reasonable evidence for micro-alloying of RE in DSSs.
基金Project supported by the National Natural Science Foundation of China(51101136)Natural Science Foundation of Hebei Province(E2012203013)+1 种基金College Science and Technology Research Project of Hebei Province,China(QN2014107)College Innovation Team Leader Training Program of Hebei Province,China(LJRC012)
文摘The effect of rare earth(RE) on creep rupture of economical 21Cr-11Ni-N heat-resistant austenitic steel was investigated at 650 °C under different stress levels. It was found that RE could increase the time to creep rupture, especially at long-term creep duration. The logarithm of the time to creep rupture(lgtr) was a linear function of the applied stress(σ). RE addition was favorable to generating a high fraction of low-coincidence site lattice(CSL) boundaries which was a possible cause for improving the creep rupture resistance. The fracture surface of RE-added steel exhibited less intergranular cracks suggesting the alteration on the nature of grain boundaries due to the presence of RE. RE addition changed the morphology of the intergranular chromium carbides from continuous network shape to fragmentary distribution which was another cause for longer creep duration. These results strongly suggested that the effect of RE alloying played a crucial role in improving the creep rupture resistance.