Electron Beam Welding (EBW) is employed to both melt and unite materials, influencing their thermal history and subsequently determining the microstructure and properties of the welded joint. Welding Titanium alloys i...Electron Beam Welding (EBW) is employed to both melt and unite materials, influencing their thermal history and subsequently determining the microstructure and properties of the welded joint. Welding Titanium alloys involves undergoing local melting and rapid solidification, subjecting the material to thermal stresses induced by a thermal expansion coefficient of 9.5 × 10 m/m°C. This process, reaching range temperatures from the full melting alloy to room temperature, results in phase formation dictated by the thermodynamic preferences of the alloyed elements, posing a significant challenge. Recent efforts in simulation and calculations have been undertaken elsewhere to address this challenge. This study focuses on a joint of two plates with differing cross-sectional areas, influencing heat transfer during welding. This report presents a case study focusing on the metallurgical changes observed in the microstructure within the welded zone, emphasizing alterations in the cooling rate of the welded joint. The investigation utilizes optical metallography, Vickers’s Hardness testing, and SEM (scanning electron microscopy) to comprehensively characterize the observed changes in addition to heat transfer simulation of the welded zone.展开更多
Nitriding of the surface in martensitic stainless steels is commonly carried out to improve their wear resistance. The process of plasma nitriding in stainless steel is influenced by two mechanisms: physical diffusion...Nitriding of the surface in martensitic stainless steels is commonly carried out to improve their wear resistance. The process of plasma nitriding in stainless steel is influenced by two mechanisms: physical diffusion through the surface and chemical gas-metal reaction. The inner nitriding interaction involves the simultaneous penetration and formation of a solid solution, as well as the interaction of nitrogen with specific alloying elements, resulting in the development of homogeneous and heterogeneous structures. Our study concludes that the observed intergranular hydrogen embrittlement and crack formation during the surface nitridation process of AMS 5719 martensite alloy steel can be attributed to the ammonium concentration of approximately 50% at a temperature of 530˚C.展开更多
In our study, stress-rupture tests were conducted at elevated temperatures to examine the impact of high temperature on MarM247 LC (low carbon). Our main objective was to investigate the alterations in the microstruct...In our study, stress-rupture tests were conducted at elevated temperatures to examine the impact of high temperature on MarM247 LC (low carbon). Our main objective was to investigate the alterations in the microstructure, particularly the carbon precipitation, during long-term stress-rupture tests. It was observed that cracks developed near the sample neck, following the path of the carbides and the gamma matrix, rather than occurring in the gamma-gamma prime eutectic. This occurred despite the formation of carbides because of prolonged exposure to high temperature and load, and the crack propagation did not follow that path. Based on these findings, we suggest that a reduction in the carbon content of Mar-M247 LC can enhance the sample's lifespan when subjected to temperatures below 760˚C and a stress of 690 MPa.展开更多
文摘Electron Beam Welding (EBW) is employed to both melt and unite materials, influencing their thermal history and subsequently determining the microstructure and properties of the welded joint. Welding Titanium alloys involves undergoing local melting and rapid solidification, subjecting the material to thermal stresses induced by a thermal expansion coefficient of 9.5 × 10 m/m°C. This process, reaching range temperatures from the full melting alloy to room temperature, results in phase formation dictated by the thermodynamic preferences of the alloyed elements, posing a significant challenge. Recent efforts in simulation and calculations have been undertaken elsewhere to address this challenge. This study focuses on a joint of two plates with differing cross-sectional areas, influencing heat transfer during welding. This report presents a case study focusing on the metallurgical changes observed in the microstructure within the welded zone, emphasizing alterations in the cooling rate of the welded joint. The investigation utilizes optical metallography, Vickers’s Hardness testing, and SEM (scanning electron microscopy) to comprehensively characterize the observed changes in addition to heat transfer simulation of the welded zone.
文摘Nitriding of the surface in martensitic stainless steels is commonly carried out to improve their wear resistance. The process of plasma nitriding in stainless steel is influenced by two mechanisms: physical diffusion through the surface and chemical gas-metal reaction. The inner nitriding interaction involves the simultaneous penetration and formation of a solid solution, as well as the interaction of nitrogen with specific alloying elements, resulting in the development of homogeneous and heterogeneous structures. Our study concludes that the observed intergranular hydrogen embrittlement and crack formation during the surface nitridation process of AMS 5719 martensite alloy steel can be attributed to the ammonium concentration of approximately 50% at a temperature of 530˚C.
文摘In our study, stress-rupture tests were conducted at elevated temperatures to examine the impact of high temperature on MarM247 LC (low carbon). Our main objective was to investigate the alterations in the microstructure, particularly the carbon precipitation, during long-term stress-rupture tests. It was observed that cracks developed near the sample neck, following the path of the carbides and the gamma matrix, rather than occurring in the gamma-gamma prime eutectic. This occurred despite the formation of carbides because of prolonged exposure to high temperature and load, and the crack propagation did not follow that path. Based on these findings, we suggest that a reduction in the carbon content of Mar-M247 LC can enhance the sample's lifespan when subjected to temperatures below 760˚C and a stress of 690 MPa.
