Laser welding with filler wire of AZ31 magnesium alloys is investigated using a CO2 laser experimental system. The effect of three different filler wires on the joint properties is researched. The results show that th...Laser welding with filler wire of AZ31 magnesium alloys is investigated using a CO2 laser experimental system. The effect of three different filler wires on the joint properties is researched. The results show that the weld appearance can be effectively improved when using laser welding with filler wire. The microhardness and tensile strength of joints are almost the same us those of the base metal when ER AZ31 or ER AZ61 wire is adopted. However, when the filler wire of ER 5356 aluminum alloy is used, the mechanical properties of flints become worse. For ER AZ31 and ER AZ61 filler wires, the microstructure of weld zone slws small dendrite grains. In comparison, for ER 5356 filler wire, the weld shows a structure of snowy dendrites and many intermetallic compounds and eutectic phases distribute in the dendrites. These intermetallic constituents with low melting point increase the tendency of hot crack and result in fiagile joint properties. Therefore, ER AZ31 and ER AZ61 wire are more suitable filler material than ER 5356 for CO2 laser welding of AZ31 magnesium alloys.展开更多
The process properties and interface behavior of CO_2 laser brazing with automatic wire feed for galvanized steel sheets were investigated, in which the brazing filler metal was CuSi3 and no flux was used. As to the a...The process properties and interface behavior of CO_2 laser brazing with automatic wire feed for galvanized steel sheets were investigated, in which the brazing filler metal was CuSi3 and no flux was used. As to the appearance quality of the brazing seams, the roles of the processing parameters, such as brazing speed, wire feeding rate, inclination and feeding direction of the wire, laser power, spot diameter and heating position, were assessed. The further investigation indicates that the behavior of the active elements Si, Mn and Zn are significantly influenced by energy input. At the interface, the microstructure of the base metal was composed of columnar crystals and the acicular α solid solution was found on the filler metal side.展开更多
The Al-Cu-Li alloy is welded by using laser beam welding,and the welding wire ER4043 is used as filler metal. The microstructure and mechanical property of welded joints are systematically investigated. Microstructure...The Al-Cu-Li alloy is welded by using laser beam welding,and the welding wire ER4043 is used as filler metal. The microstructure and mechanical property of welded joints are systematically investigated. Microstructure analyses show that the fusion zone is mainly composed of α-Al matrix phase and some strengthening phases including T,δ’,θ’,β’ and T1,etc. During welding,the weld formation and joint quality are obviously improved by the addition of Al-Si filler wire. The measurements of mechanical property indicate that,compared with that of the base metal(BM), the microhardness in the weld zone is decreased to a certain extent. Under the appropriate welding parameters,the tensile strength of welded joint reaches 369.4 MPa,which is 67.8% of that of the BM. There are many dimples on the joint fracture surface,and it mainly presents the fracture characteristic of dimple aggregation.展开更多
CO2 laser welding aluminum alloy with filler wire was studied. The results indicate that the problems in CO2 laser welding of Al alloy, such as bad appearance of weld, easily excessive penetration and low strength, ca...CO2 laser welding aluminum alloy with filler wire was studied. The results indicate that the problems in CO2 laser welding of Al alloy, such as bad appearance of weld, easily excessive penetration and low strength, can be improved effectively by using laser welding with filler wire, and the maximum tensile strength of weld can reach 94% for the base metal. It also can be found that, the linear energy have great influence on the microstructure and mechanical properties of the joint. As the heat input increases, the cellular fir-tree crystals in the weld zone become sparse and the form of tensile fracture transforms from gliding fracture to brittle fracture.展开更多
The microstructures and corrosion behaviors of AA2198-T851 alloy and weld were analyzed under corrosive conditions. Weld was formed using an innovative fiber laser welding process with AA2319 Al-Cu filler wire. The me...The microstructures and corrosion behaviors of AA2198-T851 alloy and weld were analyzed under corrosive conditions. Weld was formed using an innovative fiber laser welding process with AA2319 Al-Cu filler wire. The metallurgic morphology and distribution of the chemical compositions were determined using imaging techniques such as optical micrograph, scanning electron micrograph, high-resolution transmission electron microscopy, energy-dispersive X-ray spectrometry and X-ray diffraction. Corrosion was evaluated using an immersion test and electrochemical impedance spectroscopy in 3.5% NaC1 solution at room temperature. Results indicate that the parent alloy suffered from pitting corrosion during the initial 4-h immersion which was caused by the inhomogeneous distribution of its chemical compo- nents and the different intermetallics formed during the rolling process. The weld experienced dendritic boundary corrosion under the same conditions due to the addition of the Al-Cu filler and rapid solidification during laser welding, which led to the precipitates Cu enrichment along the grain boundary. When a welding joint was immersed in the solution for 5 days, a big crack was observed across the center of the weld. In comparison, there was good corrosion resistance in the heat- affected zone with a compact protective film.展开更多
The characteristics of weld shape,microstructure,mechanical properties and defects of 5A90 Al-Li alloy joint by laser welding (LBW) and laser welding with filler wire (LWFW) were studied and analyzed.The results indic...The characteristics of weld shape,microstructure,mechanical properties and defects of 5A90 Al-Li alloy joint by laser welding (LBW) and laser welding with filler wire (LWFW) were studied and analyzed.The results indicated that the microstructure of joint by LWFW was fine-grained layer and the equiaxed grain in most of seams,which were similar to the joint by LBW.Compared with the joint by LBW,the microstructure of joint by LWFW tended to fine,and the range of the columnar crystals zone was prone to decrease.The Microhardness of the joint by LWFW (92.57HV0.2) was lower than that by LBW (95.65HV0.2),but the uniformity was better.The ultimate tensile strength of the joint by LWFW was lower than that by LBW slightly,which reached to 73.03% and 79.22% of the base metal respectively.However,the elongation of the LWFW joint was higher than that of the LBW joint significantly,which reached to 38.65% and 20.38% of the base metal respectively.The microstructure and mechanical properties of 5A90 Al-Li alloy by LWFW were better than that by LBW.The defects of joint were mainly forming defects which were caused by improper parameters and porosity inside the joint,which was caused by uncleaned surface and incomplete penetration.展开更多
Double-sided weld pool shapes were determined by multiple welding parameters and wire feed parameters during pulsed GTAW with wire filler. Aiming at such a system with multiple inputs and outputs, an effective modelin...Double-sided weld pool shapes were determined by multiple welding parameters and wire feed parameters during pulsed GTAW with wire filler. Aiming at such a system with multiple inputs and outputs, an effective modeling method, consisting of the impulse signal design, model structure and parameter identification and verification, was developed based on MATLAB software. Then, dynamic neural network models, TDNNM (Topside dynamic neural network model) and BHDNNM (Backside width and topside height dynamic neural network model), were established to predict double-sided shape parameters of the weld pool. The characteristic relationship of the welding process was simulated and analyzed with the models.展开更多
In this paper, the weld pool shape control by intelligent strategy was studied. A neuron self-learning PSD controller for backside width of weld pool in pulsed GTAW with wire filler was designed. The PSD control arith...In this paper, the weld pool shape control by intelligent strategy was studied. A neuron self-learning PSD controller for backside width of weld pool in pulsed GTAW with wire filler was designed. The PSD control arithmetic was analyzed, simulating experiment by MATLAB software was done, and the validating experiments on varied heat sink workpiece and varied gap workpiece were successfully implemented. The study results show that the neuron self-learning PSD control method can attain a perfect control effect under different set values and conditions, and is suitable for the welding process with the varied structure and coefficients of control model.展开更多
This research intends to find out the optimal mechanical properties of AISI 4130 steel welded by the GTAW process. Six test plates were joined by two types of filler wire with similar chemical composition to the base ...This research intends to find out the optimal mechanical properties of AISI 4130 steel welded by the GTAW process. Six test plates were joined by two types of filler wire with similar chemical composition to the base metal, and with lower carbon content and slightly higher alloy elements content compared to the first one. Test plates then exerted three different pre-heat and post-heat treatments on both groups. The three types of heat treatments were alternatively without pre-heat and post-heat, with pre-heat only, and finally with pre-heat and post-heat. Tensile, side bends and impact tests (for weld zone and HAZ) have been conducted. Results show that using low-carbon filler wire along with pre- and post-heat resulted in outstanding mechanical properties.展开更多
The weld pool shape control by intelligent strategy was studied. In order to improve the ability of self-learning and self-adaptation of the ordinary fuzzy control, a self-learning fuzzy neural network controller (FNN...The weld pool shape control by intelligent strategy was studied. In order to improve the ability of self-learning and self-adaptation of the ordinary fuzzy control, a self-learning fuzzy neural network controller (FNNC) for backside width of weld pool in pulsed gas tungsten arc welding (GTAW) with wire filler was designed. In FNNC, the fuzzy system was expressed by an equivalence neural network, the membership functions and inference rulers were decided through the learning of the neural network. Then, the FNNC control arithmetic was analyzed, simulating experiment was done, and the validating experiments on varied heat sink workpiece and varied gap workpiece were implemented. The maximum error between the real value and the given one was 0.39mm, the mean error was 0.014mm, and the root-mean-square was 0.14mm. The real backside width was maintained around the given value. The results show that the self-learning fuzzy neural network control strategy can achieve a perfect control effect under different set values and conditions, and is suitable for the welding process with the varied structure and coefficients of control model.展开更多
文摘Laser welding with filler wire of AZ31 magnesium alloys is investigated using a CO2 laser experimental system. The effect of three different filler wires on the joint properties is researched. The results show that the weld appearance can be effectively improved when using laser welding with filler wire. The microhardness and tensile strength of joints are almost the same us those of the base metal when ER AZ31 or ER AZ61 wire is adopted. However, when the filler wire of ER 5356 aluminum alloy is used, the mechanical properties of flints become worse. For ER AZ31 and ER AZ61 filler wires, the microstructure of weld zone slws small dendrite grains. In comparison, for ER 5356 filler wire, the weld shows a structure of snowy dendrites and many intermetallic compounds and eutectic phases distribute in the dendrites. These intermetallic constituents with low melting point increase the tendency of hot crack and result in fiagile joint properties. Therefore, ER AZ31 and ER AZ61 wire are more suitable filler material than ER 5356 for CO2 laser welding of AZ31 magnesium alloys.
文摘The process properties and interface behavior of CO_2 laser brazing with automatic wire feed for galvanized steel sheets were investigated, in which the brazing filler metal was CuSi3 and no flux was used. As to the appearance quality of the brazing seams, the roles of the processing parameters, such as brazing speed, wire feeding rate, inclination and feeding direction of the wire, laser power, spot diameter and heating position, were assessed. The further investigation indicates that the behavior of the active elements Si, Mn and Zn are significantly influenced by energy input. At the interface, the microstructure of the base metal was composed of columnar crystals and the acicular α solid solution was found on the filler metal side.
基金supported by the Key Research and Development Program of Zhenjiang City(No. GY2019004).
文摘The Al-Cu-Li alloy is welded by using laser beam welding,and the welding wire ER4043 is used as filler metal. The microstructure and mechanical property of welded joints are systematically investigated. Microstructure analyses show that the fusion zone is mainly composed of α-Al matrix phase and some strengthening phases including T,δ’,θ’,β’ and T1,etc. During welding,the weld formation and joint quality are obviously improved by the addition of Al-Si filler wire. The measurements of mechanical property indicate that,compared with that of the base metal(BM), the microhardness in the weld zone is decreased to a certain extent. Under the appropriate welding parameters,the tensile strength of welded joint reaches 369.4 MPa,which is 67.8% of that of the BM. There are many dimples on the joint fracture surface,and it mainly presents the fracture characteristic of dimple aggregation.
文摘CO2 laser welding aluminum alloy with filler wire was studied. The results indicate that the problems in CO2 laser welding of Al alloy, such as bad appearance of weld, easily excessive penetration and low strength, can be improved effectively by using laser welding with filler wire, and the maximum tensile strength of weld can reach 94% for the base metal. It also can be found that, the linear energy have great influence on the microstructure and mechanical properties of the joint. As the heat input increases, the cellular fir-tree crystals in the weld zone become sparse and the form of tensile fracture transforms from gliding fracture to brittle fracture.
基金financially supported by the National Natural Science Foundation of China (Grant Number: 51505010)Beijing Natural Science Foundation (Grant Number: 2152007)
文摘The microstructures and corrosion behaviors of AA2198-T851 alloy and weld were analyzed under corrosive conditions. Weld was formed using an innovative fiber laser welding process with AA2319 Al-Cu filler wire. The metallurgic morphology and distribution of the chemical compositions were determined using imaging techniques such as optical micrograph, scanning electron micrograph, high-resolution transmission electron microscopy, energy-dispersive X-ray spectrometry and X-ray diffraction. Corrosion was evaluated using an immersion test and electrochemical impedance spectroscopy in 3.5% NaC1 solution at room temperature. Results indicate that the parent alloy suffered from pitting corrosion during the initial 4-h immersion which was caused by the inhomogeneous distribution of its chemical compo- nents and the different intermetallics formed during the rolling process. The weld experienced dendritic boundary corrosion under the same conditions due to the addition of the Al-Cu filler and rapid solidification during laser welding, which led to the precipitates Cu enrichment along the grain boundary. When a welding joint was immersed in the solution for 5 days, a big crack was observed across the center of the weld. In comparison, there was good corrosion resistance in the heat- affected zone with a compact protective film.
文摘The characteristics of weld shape,microstructure,mechanical properties and defects of 5A90 Al-Li alloy joint by laser welding (LBW) and laser welding with filler wire (LWFW) were studied and analyzed.The results indicated that the microstructure of joint by LWFW was fine-grained layer and the equiaxed grain in most of seams,which were similar to the joint by LBW.Compared with the joint by LBW,the microstructure of joint by LWFW tended to fine,and the range of the columnar crystals zone was prone to decrease.The Microhardness of the joint by LWFW (92.57HV0.2) was lower than that by LBW (95.65HV0.2),but the uniformity was better.The ultimate tensile strength of the joint by LWFW was lower than that by LBW slightly,which reached to 73.03% and 79.22% of the base metal respectively.However,the elongation of the LWFW joint was higher than that of the LBW joint significantly,which reached to 38.65% and 20.38% of the base metal respectively.The microstructure and mechanical properties of 5A90 Al-Li alloy by LWFW were better than that by LBW.The defects of joint were mainly forming defects which were caused by improper parameters and porosity inside the joint,which was caused by uncleaned surface and incomplete penetration.
文摘Double-sided weld pool shapes were determined by multiple welding parameters and wire feed parameters during pulsed GTAW with wire filler. Aiming at such a system with multiple inputs and outputs, an effective modeling method, consisting of the impulse signal design, model structure and parameter identification and verification, was developed based on MATLAB software. Then, dynamic neural network models, TDNNM (Topside dynamic neural network model) and BHDNNM (Backside width and topside height dynamic neural network model), were established to predict double-sided shape parameters of the weld pool. The characteristic relationship of the welding process was simulated and analyzed with the models.
文摘In this paper, the weld pool shape control by intelligent strategy was studied. A neuron self-learning PSD controller for backside width of weld pool in pulsed GTAW with wire filler was designed. The PSD control arithmetic was analyzed, simulating experiment by MATLAB software was done, and the validating experiments on varied heat sink workpiece and varied gap workpiece were successfully implemented. The study results show that the neuron self-learning PSD control method can attain a perfect control effect under different set values and conditions, and is suitable for the welding process with the varied structure and coefficients of control model.
文摘This research intends to find out the optimal mechanical properties of AISI 4130 steel welded by the GTAW process. Six test plates were joined by two types of filler wire with similar chemical composition to the base metal, and with lower carbon content and slightly higher alloy elements content compared to the first one. Test plates then exerted three different pre-heat and post-heat treatments on both groups. The three types of heat treatments were alternatively without pre-heat and post-heat, with pre-heat only, and finally with pre-heat and post-heat. Tensile, side bends and impact tests (for weld zone and HAZ) have been conducted. Results show that using low-carbon filler wire along with pre- and post-heat resulted in outstanding mechanical properties.
文摘The weld pool shape control by intelligent strategy was studied. In order to improve the ability of self-learning and self-adaptation of the ordinary fuzzy control, a self-learning fuzzy neural network controller (FNNC) for backside width of weld pool in pulsed gas tungsten arc welding (GTAW) with wire filler was designed. In FNNC, the fuzzy system was expressed by an equivalence neural network, the membership functions and inference rulers were decided through the learning of the neural network. Then, the FNNC control arithmetic was analyzed, simulating experiment was done, and the validating experiments on varied heat sink workpiece and varied gap workpiece were implemented. The maximum error between the real value and the given one was 0.39mm, the mean error was 0.014mm, and the root-mean-square was 0.14mm. The real backside width was maintained around the given value. The results show that the self-learning fuzzy neural network control strategy can achieve a perfect control effect under different set values and conditions, and is suitable for the welding process with the varied structure and coefficients of control model.
