In this study, metallographic analysis and nanoindentation characterization were used to analyze the properties and microstructures of as-cast nitrogen alloyed 27Cr-7Ni-4Mo super duplex stainless steel （super-DSS）. ...In this study, metallographic analysis and nanoindentation characterization were used to analyze the properties and microstructures of as-cast nitrogen alloyed 27Cr-7Ni-4Mo super duplex stainless steel （super-DSS）. The as-cast microstructure of the super-DSS was characterized by its ferrite and island-like austenite phases. During the solution annealing process, the austenite volume percentage of the steel decreased gradually with increased annealing temperature. As a main element, the chromium content in the ferritic and austenitic phases elevated slightly at first then decreased with increased annealing temperature. The chromium partition coefficient in the steel varied by around 1.0. The contents of nickel, another main alloy element, also increased in the ferritic and austenitic phases with increased annealing temperature, as did the nickel partition coefficient in the steel, which tended to be close to 1.0. The nanoindentation characterization results indicate that the hardness of the austenite phase is slightly greater than that of the ferrite phase. They were similar to each other within a certain temperature range from 1 050 ℃ to 1 100℃. This temperature range was consistent with the temperature range in which the content ratio of the two phases was close to 1： 1. We found the Young＇ s modulus of the ferrite phase to be greater than that of the austenite phase. With increased annealing temperature, the Young＇ s modulus of the ferrite phase decreased while that of the austenite phase remained almost unchanged.展开更多
文摘In this study, metallographic analysis and nanoindentation characterization were used to analyze the properties and microstructures of as-cast nitrogen alloyed 27Cr-7Ni-4Mo super duplex stainless steel （super-DSS）. The as-cast microstructure of the super-DSS was characterized by its ferrite and island-like austenite phases. During the solution annealing process, the austenite volume percentage of the steel decreased gradually with increased annealing temperature. As a main element, the chromium content in the ferritic and austenitic phases elevated slightly at first then decreased with increased annealing temperature. The chromium partition coefficient in the steel varied by around 1.0. The contents of nickel, another main alloy element, also increased in the ferritic and austenitic phases with increased annealing temperature, as did the nickel partition coefficient in the steel, which tended to be close to 1.0. The nanoindentation characterization results indicate that the hardness of the austenite phase is slightly greater than that of the ferrite phase. They were similar to each other within a certain temperature range from 1 050 ℃ to 1 100℃. This temperature range was consistent with the temperature range in which the content ratio of the two phases was close to 1： 1. We found the Young＇ s modulus of the ferrite phase to be greater than that of the austenite phase. With increased annealing temperature, the Young＇ s modulus of the ferrite phase decreased while that of the austenite phase remained almost unchanged.
