Taiyuan, China
Taiyuan, China

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Qiao Y.,Taiyuan University of Technology | Wang J.,Taiyuan University of Technology | Zhang Z.,Taiyuan University of Technology | Quan X.,Taiyuan University of Technology | And 3 more authors.
Oxidation of Metals | Year: 2017

The oxidation resistance of austenitic stainless steels modified with various aluminum contents was investigated. The weight gain per unit area is in parabolic relation to oxidation time, and the oxidation rate significantly decreases with increased aluminum content. Outer layer oxides of austenitic stainless steel transform from Cr2O3 to a composite oxide layer comprising Cr and Al, and more dense Al-containing oxides formed with increasing the added Al contents. Since the diffusion of element Al is enhanced and the diffusion of element Cr is inhibited, the oxides enriched in Al dramatically contribute to the improved oxidation resistance of austenitic stainless steels at high temperature. The possible oxidation mechanisms are also proposed based on microstructural observations. © 2017 Springer Science+Business Media New York

Li J.,Taiyuan University of Technology | Li J.,Taiyuan Iron & Steel Co. | Liang W.,Taiyuan University of Technology | Li G.,Taiyuan Iron & Steel Co. | Zhang S.,Taiyuan Iron & Steel Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

Erosion effect on microstructure of duplex stainless steel 2906 was studied with different etching methods such as electrolytic etching in oxalic acid solution or in potassium hydroxide solution and immersed etching way in hot basic potassium ferricyanide solution or chloroazotic acid. The results show that after electrolytic etching with oxalic acid solution the microstructure of duplex stainless steel could be revealed, but the color distinction between the ferrite and austenite phase is not apparent by optical microscope. The microstructure of dual phases is distinguished after immersed etching with hot basic potassium ferricyanide solution or potassium hydroxide solution and the percentage of ferrite or austenite could be determined by metallographic image software, and the harmful phase such as σ phase could be found too. The grain boundary of austenite and ferrite phase would be displayed simultaneously after etching with chloroazotic acid. ©, 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.

Li J.-C.,Taiyuan University of Technology | Li J.-C.,Taiyuan Iron & Steel Co. | Liang W.,Taiyuan University of Technology
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2014

Effects of the solution temperature on the microstructure of 00Cr20Ni18Mo6CuN superaustenitic stainless steel plate were investigated by OM, SEM and TEM. The results showed that the grain size of material was getting coarser with the increase of the solution temperature. A large number of the second phases precipitated when the solution temperature changed between 950~1 250℃. When the solution temperature was more than 1 150℃, no second phases were observed in the microstructure of the steel by SEM. Precipitating phases in the different positions of the austenitic matrix were identified as χ phase and σ phase in the tested steel by TEM. ©, 2014, Northeastern University. All right reserved.

Li H.,University of Science and Technology Beijing | Jiang H.,University of Science and Technology Beijing | Yang L.,University of Science and Technology Beijing | Wang Y.,University of Science and Technology Beijing | Wang Y.,Taiyuan Iron & Steel Co.
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2014

To evaluate the welding performance of TWIP steel, the results of laser welding of 1.2 mm Fe-Mn-C series TWIP steels were presented in this paper. Energy-dispersive X-ray spectrometry (EDX) was used to detect the effect of manganese segregation. Microhardness and tensile tests were performed to evaluate the mechanical properties of the joints. The fracture mechanism was observed by scanning electron microscopy (SEM). The twinning phenomena was assessed by electron back-scatter diffraction (EBSD) analyses. The results indicate that there is no manganese evaporation in the FZ area, it is dendritic structures at room temperature. Fracture all occurs in the FZ due to the welding defects such as voids, and the strength of the joint is similar to that of the base metal. However, the toughness is reduced remarkably. Twinning is the predominant deformation mechanism, the microstructure of welding joint are all austenite. ©, 2014, Harbin Institute of Technology. All right reserved.

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