The microstructures and mechanical properties of Cr13 super martensitic stainless steel after different heat treatments were studied. The results show that the structures of the steel after quenching are of lath marte...The microstructures and mechanical properties of Cr13 super martensitic stainless steel after different heat treatments were studied. The results show that the structures of the steel after quenching are of lath martensite mixed with a small amount of retained austenite. With the raising quenching temperature, the original austenite grain size increases and the lath martensite gradually becomes thicker. The structures of the tempered steel are mixtures of tempered martensite and reversed austenite dispersed in the martensite matrix. The amount of reversed austenite is from 7.54% to 22. 49%. After different heat treatments, the tensile strength, the elongation and the HRC hardness of the steel are in the range of 813 1 070 MPa, 10.1%--21.2% and 21.33--32.37, respectively. The steel displays the best comprehensive mechanical properties after the sample is quenched at 1 050 ℃ followed by tempering at 650 ℃.展开更多
The effect of different heat treatments on the reversed austenite in Cr15 super martensitic stainless steel was investigated. The experimental results indicate that the microstructure of the steel is composed of tempe...The effect of different heat treatments on the reversed austenite in Cr15 super martensitic stainless steel was investigated. The experimental results indicate that the microstructure of the steel is composed of tempered martensite and diffused reversed austenite after quenching at 1 050 ℃ and tempering from 550 to 750 ℃. The volume fraction and size of reversed austenite increase with increasing tempering temperature and both of them reach the maximum value at 700 ℃. The volume fraction and size of reversed austenite decrease when the temperature is above 700 ℃. The transmission electron microscope （TEM） results indicate that the orientation relationship between tempered martensite and reversed austenite belongs to Kurdjmov-Sach （K-S） relationship.展开更多
The passivation behaviors of super martensitic stainless steels （SMSS） were studied by polarization curves at passive potential of -0.1 V and in various NaC1 solutions, electrochemical impedance spectroscopy （EIS）...The passivation behaviors of super martensitic stainless steels （SMSS） were studied by polarization curves at passive potential of -0.1 V and in various NaC1 solutions, electrochemical impedance spectroscopy （EIS） and X- ray photoelectron spectroscopy （XPS） analysis. Electrochemical test results showed that, in alkaline solutions, pas- sivation region width was wider, passivation current was smaller, and polarization resistance was greater~ thus, the passive film of SMSS in alkaline solutions had better passivation behaviors than that in acidic solutions. The polariza- tion curve and EIS of samples SMSS1 and SMSS2 were also used to study which sample had better passivation be- haviors. All results demonstrated that passive film structure of SMSS1 sample was more stable, and capacity of pas- sive film was enhanced. The impact of alloying elements on the passive film （SMSS） passivation capability was also discussed by XPS depth profiling, and XPS depth profiling showed that the composition of the passive film was mainly composed of Fe-oxide and Cr-oxide. So the passive film structures were mixed layers of Fe-oxide and Cr-ox- ide. Fe oxidation product and Cr oxidation product would help to improve the protective property of passive film, which could promote the formation of a passive film structure more stably and densely.展开更多
文摘The microstructures and mechanical properties of Cr13 super martensitic stainless steel after different heat treatments were studied. The results show that the structures of the steel after quenching are of lath martensite mixed with a small amount of retained austenite. With the raising quenching temperature, the original austenite grain size increases and the lath martensite gradually becomes thicker. The structures of the tempered steel are mixtures of tempered martensite and reversed austenite dispersed in the martensite matrix. The amount of reversed austenite is from 7.54% to 22. 49%. After different heat treatments, the tensile strength, the elongation and the HRC hardness of the steel are in the range of 813 1 070 MPa, 10.1%--21.2% and 21.33--32.37, respectively. The steel displays the best comprehensive mechanical properties after the sample is quenched at 1 050 ℃ followed by tempering at 650 ℃.
文摘The effect of different heat treatments on the reversed austenite in Cr15 super martensitic stainless steel was investigated. The experimental results indicate that the microstructure of the steel is composed of tempered martensite and diffused reversed austenite after quenching at 1 050 ℃ and tempering from 550 to 750 ℃. The volume fraction and size of reversed austenite increase with increasing tempering temperature and both of them reach the maximum value at 700 ℃. The volume fraction and size of reversed austenite decrease when the temperature is above 700 ℃. The transmission electron microscope （TEM） results indicate that the orientation relationship between tempered martensite and reversed austenite belongs to Kurdjmov-Sach （K-S） relationship.
基金Item Sponsored by Education Department Scientific Research Fund Project from Yunnan Province of China(2012Y544)
文摘The passivation behaviors of super martensitic stainless steels （SMSS） were studied by polarization curves at passive potential of -0.1 V and in various NaC1 solutions, electrochemical impedance spectroscopy （EIS） and X- ray photoelectron spectroscopy （XPS） analysis. Electrochemical test results showed that, in alkaline solutions, pas- sivation region width was wider, passivation current was smaller, and polarization resistance was greater~ thus, the passive film of SMSS in alkaline solutions had better passivation behaviors than that in acidic solutions. The polariza- tion curve and EIS of samples SMSS1 and SMSS2 were also used to study which sample had better passivation be- haviors. All results demonstrated that passive film structure of SMSS1 sample was more stable, and capacity of pas- sive film was enhanced. The impact of alloying elements on the passive film （SMSS） passivation capability was also discussed by XPS depth profiling, and XPS depth profiling showed that the composition of the passive film was mainly composed of Fe-oxide and Cr-oxide. So the passive film structures were mixed layers of Fe-oxide and Cr-ox- ide. Fe oxidation product and Cr oxidation product would help to improve the protective property of passive film, which could promote the formation of a passive film structure more stably and densely.
