An axial symmetry finite element model coupled with electricity-thermal effect was developed to study the temperature field distribution in process of the flash butt welding (FBW) of frog high-manganese steel. The inf...An axial symmetry finite element model coupled with electricity-thermal effect was developed to study the temperature field distribution in process of the flash butt welding (FBW) of frog high-manganese steel. The influence of temperature dependent material properties and the contact resistance were taken into account in FEM simulation. Meanwhile, the lost materials due to splutter was resolved by using birth and death element. The result of analyzing data shows that the model in the FBW flashing is reasonable and feasible, and can exactly simulate the temperature field distribution. The modeling provides reference for analysis of welding technologies on the temperature field of high-manganese steel in FBW.展开更多
Under the spirit of sustainable development,‘lightweight'has been gradually included into the vehicle design criterion by many manufacturers and used in automobile production. Following this trend,domestic wheel ...Under the spirit of sustainable development,‘lightweight'has been gradually included into the vehicle design criterion by many manufacturers and used in automobile production. Following this trend,domestic wheel suppliers also begin to study the technology of lightweight wheel. One way to achieve this goal is improving strength grade of the steel and optimizing the structure design in the field of steel wheels. But there are a few problems in flash butt welding process in the application of high strength steel,leading to high rejection rates. SW400 steel is a special high strength wheel steel developed by Benxi Steel. Taking SW400 steel as the research material,this article studys the feasibility of improving the properties of rim flash butt welded joints by adding preheating process.展开更多
Many processes are used to join reinforcing bar (steel bar), but only a few of them, e.g. overlapping welding, gas pressure welding, thread joining, cold pressure sleeve joining, are able to be used on building sites ...Many processes are used to join reinforcing bar (steel bar), but only a few of them, e.g. overlapping welding, gas pressure welding, thread joining, cold pressure sleeve joining, are able to be used on building sites because the conditions of building sites are very particular. First, the work of joining reinforcing bar is mobile, that is to say, it must be moved from one place to another after having accomplished one joint. So it demands that the welding equipment (especially the welding head) must be convenient for moving. So it must be small and light. Second, the electricity capacity of the welding equipment can not be too large because the whole electricity capacity of a building site is limited. Third, the welding process ought to be simple because the situation og building sites is very poor and is on the open air. The more complex the process is, the more difficult the work will be. Fourth, the quality of the joint should be reliable and stable because it is impossible to check the quality of every joint, and there is no suitable way to do it even by now. For those reasons, the electroslag pressure butt welding has got great development recent years and is just suitable to be used on building sites to join vertical reinforcing bars. The article introduces its basic principle, processing, chief properties, and some test results.展开更多
In order to propose high effective simulation using finite element method (FEM) for predicting deformation and residual stress generated by one pass butt welding, a series of numerical analyses were carried out. By id...In order to propose high effective simulation using finite element method (FEM) for predicting deformation and residual stress generated by one pass butt welding, a series of numerical analyses were carried out. By idealizing the movement of heat source (the instantaneous heat input method), the tendency of welding out-of-plane deformation and the residual stress distribution could be predicted. The computing time was around 9% of that by the precise model with considering the movement of heat source. On the other hand, applicability of two dimensional shell elements instead of generally used three dimensional solid elements was examined. The heat input model with considering the temperature distribution in the thickness direction was proposed for the simulation by using the shell elements. It was confirmed that the welding out-of-plane deformation and residual stress could be predicted with high accuracy by the model with shell elements and the distributed heat input methods. The computing time was around 8% of that by the precise model with solid elements.展开更多
Arc pressure is the key influencing factor to forming of molten pool. Countering the characteristic of tungsten inert gas arc welding with micro gap for tantalum sheet, according to the fundament of arc physics, a dis...Arc pressure is the key influencing factor to forming of molten pool. Countering the characteristic of tungsten inert gas arc welding with micro gap for tantalum sheet, according to the fundament of arc physics, a distribution model of arc pressure and forming mechanism of molten pool with micro butt gap are proposed, and the influences of arc pressure on forming of molten pool are discussed. Experimental researches for the dynamic formation process of weld molten pool by using high-speed vidicon camera show that when butt gap is appropriate, that is from 0.1 to 0.15 mm, molten metals formed on two workpiece uplift and grow up first, then are fused and form uniform molten pool finally.展开更多
The hardware and software design of two digital control systems based on 80C196KB MCU for flash butt welder is introduced in this paper.The welding power supply is made of six-phase half-wave rectifier.The welding out...The hardware and software design of two digital control systems based on 80C196KB MCU for flash butt welder is introduced in this paper.The welding power supply is made of six-phase half-wave rectifier.The welding outer characteristic of welding machine is realized by digital PI algorithm with the voltage close-loop feedback.The flashing curve is finished by elec- tric-hydraulic servo valve.The process control system transfers datum with power supply system by a serial communication inter- face.The parameters of the control systems are collected by photoelectrical seclusion to avoid the disturbing of the electromagnetism in welding process.展开更多
The fatigue properties of friction stir welded(FSW) butt joint and base metal of MB8 magnesium alloy were investigated.The comparative fatigue tests were carried out using EHF-EM200K2-070-1A fatigue testing machine fo...The fatigue properties of friction stir welded(FSW) butt joint and base metal of MB8 magnesium alloy were investigated.The comparative fatigue tests were carried out using EHF-EM200K2-070-1A fatigue testing machine for both FSW butt joint and base metal specimens.The fatigue fractures were observed and analyzed using a scanning electron microscope of JSM-6063 LA type.The experimental results show that the fatigue performance of the FSW butt joint of MB8 magnesium alloy is sharply decreased.The conditional fatigue limit(2 × 10~6) of base metal and welded butt joint is about77.44 MPa and 49.91 MPa,respectively.The conditional fatigue limit(2 × 10~6) of the welded butt joint is 64.45%of that of base metal.The main reasons are that the welding can lead to stress concentration in the flash area,tensile welding residual stress in the welded joint(The residual stress value was 30.5 MPa),as well as the grain size is not uniform in the heat-affected zone.The cleavage steps or quasi-cleavage patterns present on the fatigue fracture surface,the fracture type of the FSW butt joint belongs to a brittle fracture.展开更多
This paper presents an experimental investigation of laser welding low carbon galvanized steel in butt-joint configurations. The experimental work is focused on the effects of various laser welding parameters on the w...This paper presents an experimental investigation of laser welding low carbon galvanized steel in butt-joint configurations. The experimental work is focused on the effects of various laser welding parameters on the welds quality. The investigations are based on a structured experimental design using the Taguchi method. Welding experiments are conducted using a 3 kW Nd:YAG laser source. The selected laser welding parameters (laser power, welding speed, laser fiber diameter, gap between sheets and sheet thickness) are combined and used to evaluate the variation of four weld quality attributes (bead width, penetration depth, underfill and hardness) and to identify the possible relationship between welding parameters and weld physical and geometrical attributes. The effects of these parameters are studied using ANOVA to find their contributions to the variation of different weld characteristics. Plots of the main effects and the interaction effects are also used to understand the influence of the welding parameters. The results reveal that all welding parameters are relevant to bead width (BDW) and depth of penetration (DOP) with a relative predominance of laser power and welding speed. The effect of laser fiber diameter on penetration depth is insignificant. Typical gap-dependent weld shapes show that a small gap results in a narrower and deeper weld. Due to the standard sheared edge, an underfill between 5% and 10% occurs for no-gap experiments. The resulting hardness values are relatively similar for all the experimental tests.展开更多
文摘An axial symmetry finite element model coupled with electricity-thermal effect was developed to study the temperature field distribution in process of the flash butt welding (FBW) of frog high-manganese steel. The influence of temperature dependent material properties and the contact resistance were taken into account in FEM simulation. Meanwhile, the lost materials due to splutter was resolved by using birth and death element. The result of analyzing data shows that the model in the FBW flashing is reasonable and feasible, and can exactly simulate the temperature field distribution. The modeling provides reference for analysis of welding technologies on the temperature field of high-manganese steel in FBW.
基金supported by the Key Science and Technology of Jilin Province(Grant No.20140204070GX)
文摘Under the spirit of sustainable development,‘lightweight'has been gradually included into the vehicle design criterion by many manufacturers and used in automobile production. Following this trend,domestic wheel suppliers also begin to study the technology of lightweight wheel. One way to achieve this goal is improving strength grade of the steel and optimizing the structure design in the field of steel wheels. But there are a few problems in flash butt welding process in the application of high strength steel,leading to high rejection rates. SW400 steel is a special high strength wheel steel developed by Benxi Steel. Taking SW400 steel as the research material,this article studys the feasibility of improving the properties of rim flash butt welded joints by adding preheating process.
文摘Many processes are used to join reinforcing bar (steel bar), but only a few of them, e.g. overlapping welding, gas pressure welding, thread joining, cold pressure sleeve joining, are able to be used on building sites because the conditions of building sites are very particular. First, the work of joining reinforcing bar is mobile, that is to say, it must be moved from one place to another after having accomplished one joint. So it demands that the welding equipment (especially the welding head) must be convenient for moving. So it must be small and light. Second, the electricity capacity of the welding equipment can not be too large because the whole electricity capacity of a building site is limited. Third, the welding process ought to be simple because the situation og building sites is very poor and is on the open air. The more complex the process is, the more difficult the work will be. Fourth, the quality of the joint should be reliable and stable because it is impossible to check the quality of every joint, and there is no suitable way to do it even by now. For those reasons, the electroslag pressure butt welding has got great development recent years and is just suitable to be used on building sites to join vertical reinforcing bars. The article introduces its basic principle, processing, chief properties, and some test results.
文摘In order to propose high effective simulation using finite element method (FEM) for predicting deformation and residual stress generated by one pass butt welding, a series of numerical analyses were carried out. By idealizing the movement of heat source (the instantaneous heat input method), the tendency of welding out-of-plane deformation and the residual stress distribution could be predicted. The computing time was around 9% of that by the precise model with considering the movement of heat source. On the other hand, applicability of two dimensional shell elements instead of generally used three dimensional solid elements was examined. The heat input model with considering the temperature distribution in the thickness direction was proposed for the simulation by using the shell elements. It was confirmed that the welding out-of-plane deformation and residual stress could be predicted with high accuracy by the model with shell elements and the distributed heat input methods. The computing time was around 8% of that by the precise model with solid elements.
文摘Arc pressure is the key influencing factor to forming of molten pool. Countering the characteristic of tungsten inert gas arc welding with micro gap for tantalum sheet, according to the fundament of arc physics, a distribution model of arc pressure and forming mechanism of molten pool with micro butt gap are proposed, and the influences of arc pressure on forming of molten pool are discussed. Experimental researches for the dynamic formation process of weld molten pool by using high-speed vidicon camera show that when butt gap is appropriate, that is from 0.1 to 0.15 mm, molten metals formed on two workpiece uplift and grow up first, then are fused and form uniform molten pool finally.
文摘The hardware and software design of two digital control systems based on 80C196KB MCU for flash butt welder is introduced in this paper.The welding power supply is made of six-phase half-wave rectifier.The welding outer characteristic of welding machine is realized by digital PI algorithm with the voltage close-loop feedback.The flashing curve is finished by elec- tric-hydraulic servo valve.The process control system transfers datum with power supply system by a serial communication inter- face.The parameters of the control systems are collected by photoelectrical seclusion to avoid the disturbing of the electromagnetism in welding process.
基金supported by the National Natural Science Foundation(No.51265013)the Natural Science Foundation of Jiangxi Province(No.20151BAB206007)
文摘The fatigue properties of friction stir welded(FSW) butt joint and base metal of MB8 magnesium alloy were investigated.The comparative fatigue tests were carried out using EHF-EM200K2-070-1A fatigue testing machine for both FSW butt joint and base metal specimens.The fatigue fractures were observed and analyzed using a scanning electron microscope of JSM-6063 LA type.The experimental results show that the fatigue performance of the FSW butt joint of MB8 magnesium alloy is sharply decreased.The conditional fatigue limit(2 × 10~6) of base metal and welded butt joint is about77.44 MPa and 49.91 MPa,respectively.The conditional fatigue limit(2 × 10~6) of the welded butt joint is 64.45%of that of base metal.The main reasons are that the welding can lead to stress concentration in the flash area,tensile welding residual stress in the welded joint(The residual stress value was 30.5 MPa),as well as the grain size is not uniform in the heat-affected zone.The cleavage steps or quasi-cleavage patterns present on the fatigue fracture surface,the fracture type of the FSW butt joint belongs to a brittle fracture.
文摘This paper presents an experimental investigation of laser welding low carbon galvanized steel in butt-joint configurations. The experimental work is focused on the effects of various laser welding parameters on the welds quality. The investigations are based on a structured experimental design using the Taguchi method. Welding experiments are conducted using a 3 kW Nd:YAG laser source. The selected laser welding parameters (laser power, welding speed, laser fiber diameter, gap between sheets and sheet thickness) are combined and used to evaluate the variation of four weld quality attributes (bead width, penetration depth, underfill and hardness) and to identify the possible relationship between welding parameters and weld physical and geometrical attributes. The effects of these parameters are studied using ANOVA to find their contributions to the variation of different weld characteristics. Plots of the main effects and the interaction effects are also used to understand the influence of the welding parameters. The results reveal that all welding parameters are relevant to bead width (BDW) and depth of penetration (DOP) with a relative predominance of laser power and welding speed. The effect of laser fiber diameter on penetration depth is insignificant. Typical gap-dependent weld shapes show that a small gap results in a narrower and deeper weld. Due to the standard sheared edge, an underfill between 5% and 10% occurs for no-gap experiments. The resulting hardness values are relatively similar for all the experimental tests.
