Micro welding of dissimilar metals can meet many performance requirements for modern engineering structures. In this experiment, laser micro welding of copper-aluminum dissimilar metals was conducted with an HWLW-300A...Micro welding of dissimilar metals can meet many performance requirements for modern engineering structures. In this experiment, laser micro welding of copper-aluminum dissimilar metals was conducted with an HWLW-300A energy negative feedback Nd:YAG pulse laser. By using the overlap welding method with copper on aluminum, with the laser energy being distributed unevenly, good weld joints were obtained. In this paper, the welding mechanism was analyzed from aspects such as welding temperature and the specific heat capacity of the solid metal. Existing defects were identified, and a feasible improvement scheme was proposed.展开更多
Friction stir spot welding technique was used to join dissimilar combinations of aluminium alloy(Al5052)with copperalloy(C27200)and friction stir spot welding windows such as tool rotational speed–dwell time and tool...Friction stir spot welding technique was used to join dissimilar combinations of aluminium alloy(Al5052)with copperalloy(C27200)and friction stir spot welding windows such as tool rotational speed–dwell time and tool rotational speed?plungedepth diagrams for effective joining of these materials were developed.Using a central composite design model,empirical relationswere developed to predict the changes in tensile shear failure load values and interface hardness of the joints with three processparameters such as tool rotational speed,plunge depth and dwell time.The adequacy of the developed model was verified usingANOVA analysis at95%confidence level.Response surface methodology was used to optimize the developed model to maximizetensile strength and minimize interface hardness.A high tensile shear failure load value of3850N and low interface hardness valueof HV81was observed for joints made under optimum conditions,and validation experiments confirmed the high predictability ofthe developed model with error less than2%.The operating windows developed shall act as reference maps for future designengineers in choosing appropriate friction stir spot welding process parameter values to obtain good joints.展开更多
Aluminium-copper hybrid parts, as a substitution to copper parts, result in weight and cost reduction, and are relevant in applications related to the electronic, heating and cooling sector. However, aluminium to copp...Aluminium-copper hybrid parts, as a substitution to copper parts, result in weight and cost reduction, and are relevant in applications related to the electronic, heating and cooling sector. However, aluminium to copper joined by thermal welding processes presents challenges in terms of achieving good joint quality. This is attributed to their dissimilar mechanical and thermal properties which result in large stress gradients during heating. This study investigated joining of aluminium to copper sheets by electromagnetic pulse welding, which is a solid-state process that uses electromagnetic forces for joining of dissimilar materials. Hybrid sheet welds were obtained for all parameters conditions, selected according to a Taguchi L18 design. The structural and mechanical characteristics were examined and related to the welding parameters by means of a Pareto analysis and response graphs. The welded zone started with a wavy interface with interfacial layers and defects and evolved to a flat interface without interfacial layers. The maximum transferable force depended on the minimum specimen thickness and the strength of the hybrid sheet weld. In case of aluminium sheet thickness reduction, the maximum transferable force was linearly correlated with the aluminium sheet thickness. High quality joints were obtained for no aluminium sheet thickness reduction and for a sheet weld strength which was at least as high as that of the base material. The most effective way to increase the transferable force was to lower the initial gap and to increase the free length, which resulted in no aluminium sheet thickness reduction. Alternatively, the use of a rounded spacer decreased the effect of the aluminium sheet thickness on the transferable force. An increase in weld width was achieved for an increase in capacitor charging energy and gap, whereas an increase in weld length was obtained for a decrease in gap. An increase in weld width did not necessarily result in an increase in the transferable force. In the regarded cases, a hybrid sheet with narrow weld width could therefore have higher quality.展开更多
This paper mainly concentrated on the feasibility of friction stir welding of dissimilar metal of aluminum alloy to copper （I2） and a preliminary analysis of welding parameters influencing on the microstructures and...This paper mainly concentrated on the feasibility of friction stir welding of dissimilar metal of aluminum alloy to copper （I2） and a preliminary analysis of welding parameters influencing on the microstructures and properties of joint was carried out. The results indicated that the thickness of workpiece played an important role in the welding parameters which could succeed in the friction stir welding of dissimilar metal of copper to aluminum alloy, and the parameters were proved to be a narrow choice. The interfacial region between copper and aluminum in the dissimilar joint was not uniformly mixed, constituted with part of incomplete mixing zone, complete mixing zone, dispersion zone and the most region＇ s boundary was obvious. Meantime a kind banded structure with inhomogeneous width was formed. The intermetallic compounds generated during friction stir welding in the interfacial region were mainly CugAl4, Al2Cu etc, and their hardness was higher than oihers.展开更多
An optical sensing system was constructed to study the coating when joining ahtminium alloy to zinc-coated steel by MIG welding-brazing process. The results showed that the coating fused to form a liquid zinc film on ...An optical sensing system was constructed to study the coating when joining ahtminium alloy to zinc-coated steel by MIG welding-brazing process. The results showed that the coating fused to form a liquid zinc film on surface during process. The Al-Si filler metal reacted with the liquid zinc film to improve the spreadability of filler metal and thus a new method was established to join aluminium alloy and uncoated steel by depositing a mixed layer on steel surface.展开更多
采用冷金属过渡(Cold metal transfer,CMT)技术,以镍铝青铜ERCuNiAl焊丝作为填充材料,对钛合金Ti6Al4V和纯铜T2异种金属薄板进行钛板在上铜板在下的搭接连接。使用扫描电镜和能谱分析研究焊接接头的显微组织和反应界面金属间化合物的组...采用冷金属过渡(Cold metal transfer,CMT)技术,以镍铝青铜ERCuNiAl焊丝作为填充材料,对钛合金Ti6Al4V和纯铜T2异种金属薄板进行钛板在上铜板在下的搭接连接。使用扫描电镜和能谱分析研究焊接接头的显微组织和反应界面金属间化合物的组成,并通过横向拉伸试验对接头的力学性能进行评定。研究结果表明,冷金属过渡技术可以实现于钛/铜异种金属的有效连接。焊接过程中电弧比较稳定,焊缝成形良好。在电弧热的作用下,铜板完全熔透,与焊缝金属形成铜-焊缝界面,钛板部分熔化,铜板和焊丝熔化包围在钛板的周围,形成了钛和焊缝的三个界面,提高了接头的力学性能。钛侧金属间化合物层包含TiCu、TiAl、Ti2Cu、AlCu2Ti和铜基固溶体等多种金属间化合物。拉伸试验时,断裂发生在铜母材的热影响区,拉剪强度可达200 MPa。展开更多
运用相位摩擦焊技术实现电解铝阳极铝-钢的大端面焊接,替代了传统电解铝中铝-钢爆炸焊块作过渡的连接方式。在此主要研究了铝-钢摩擦焊接头的各项力学性能,并模拟真实电解环境对焊接件进行了电阻检测试验,试验结果表明:铝-钢摩擦焊接头...运用相位摩擦焊技术实现电解铝阳极铝-钢的大端面焊接,替代了传统电解铝中铝-钢爆炸焊块作过渡的连接方式。在此主要研究了铝-钢摩擦焊接头的各项力学性能,并模拟真实电解环境对焊接件进行了电阻检测试验,试验结果表明:铝-钢摩擦焊接头可承受的最高平均负载为88 t,高于传统型接头59 t;温度350℃、通电电流7 k A条件下,铝-钢摩擦焊技术可实现降低阳极压降约8 m V。展开更多
文摘Micro welding of dissimilar metals can meet many performance requirements for modern engineering structures. In this experiment, laser micro welding of copper-aluminum dissimilar metals was conducted with an HWLW-300A energy negative feedback Nd:YAG pulse laser. By using the overlap welding method with copper on aluminum, with the laser energy being distributed unevenly, good weld joints were obtained. In this paper, the welding mechanism was analyzed from aspects such as welding temperature and the specific heat capacity of the solid metal. Existing defects were identified, and a feasible improvement scheme was proposed.
文摘Friction stir spot welding technique was used to join dissimilar combinations of aluminium alloy(Al5052)with copperalloy(C27200)and friction stir spot welding windows such as tool rotational speed–dwell time and tool rotational speed?plungedepth diagrams for effective joining of these materials were developed.Using a central composite design model,empirical relationswere developed to predict the changes in tensile shear failure load values and interface hardness of the joints with three processparameters such as tool rotational speed,plunge depth and dwell time.The adequacy of the developed model was verified usingANOVA analysis at95%confidence level.Response surface methodology was used to optimize the developed model to maximizetensile strength and minimize interface hardness.A high tensile shear failure load value of3850N and low interface hardness valueof HV81was observed for joints made under optimum conditions,and validation experiments confirmed the high predictability ofthe developed model with error less than2%.The operating windows developed shall act as reference maps for future designengineers in choosing appropriate friction stir spot welding process parameter values to obtain good joints.
文摘Aluminium-copper hybrid parts, as a substitution to copper parts, result in weight and cost reduction, and are relevant in applications related to the electronic, heating and cooling sector. However, aluminium to copper joined by thermal welding processes presents challenges in terms of achieving good joint quality. This is attributed to their dissimilar mechanical and thermal properties which result in large stress gradients during heating. This study investigated joining of aluminium to copper sheets by electromagnetic pulse welding, which is a solid-state process that uses electromagnetic forces for joining of dissimilar materials. Hybrid sheet welds were obtained for all parameters conditions, selected according to a Taguchi L18 design. The structural and mechanical characteristics were examined and related to the welding parameters by means of a Pareto analysis and response graphs. The welded zone started with a wavy interface with interfacial layers and defects and evolved to a flat interface without interfacial layers. The maximum transferable force depended on the minimum specimen thickness and the strength of the hybrid sheet weld. In case of aluminium sheet thickness reduction, the maximum transferable force was linearly correlated with the aluminium sheet thickness. High quality joints were obtained for no aluminium sheet thickness reduction and for a sheet weld strength which was at least as high as that of the base material. The most effective way to increase the transferable force was to lower the initial gap and to increase the free length, which resulted in no aluminium sheet thickness reduction. Alternatively, the use of a rounded spacer decreased the effect of the aluminium sheet thickness on the transferable force. An increase in weld width was achieved for an increase in capacitor charging energy and gap, whereas an increase in weld length was obtained for a decrease in gap. An increase in weld width did not necessarily result in an increase in the transferable force. In the regarded cases, a hybrid sheet with narrow weld width could therefore have higher quality.
基金This project is supported by National Natural Science Foundation of China ( NSFC)(10577010)
文摘This paper mainly concentrated on the feasibility of friction stir welding of dissimilar metal of aluminum alloy to copper （I2） and a preliminary analysis of welding parameters influencing on the microstructures and properties of joint was carried out. The results indicated that the thickness of workpiece played an important role in the welding parameters which could succeed in the friction stir welding of dissimilar metal of copper to aluminum alloy, and the parameters were proved to be a narrow choice. The interfacial region between copper and aluminum in the dissimilar joint was not uniformly mixed, constituted with part of incomplete mixing zone, complete mixing zone, dispersion zone and the most region＇ s boundary was obvious. Meantime a kind banded structure with inhomogeneous width was formed. The intermetallic compounds generated during friction stir welding in the interfacial region were mainly CugAl4, Al2Cu etc, and their hardness was higher than oihers.
基金Acknowledgements The research was sponsored by Project 50905045 supported by the National Natural Science Foundation of China and State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology.
文摘An optical sensing system was constructed to study the coating when joining ahtminium alloy to zinc-coated steel by MIG welding-brazing process. The results showed that the coating fused to form a liquid zinc film on surface during process. The Al-Si filler metal reacted with the liquid zinc film to improve the spreadability of filler metal and thus a new method was established to join aluminium alloy and uncoated steel by depositing a mixed layer on steel surface.
文摘采用冷金属过渡(Cold metal transfer,CMT)技术,以镍铝青铜ERCuNiAl焊丝作为填充材料,对钛合金Ti6Al4V和纯铜T2异种金属薄板进行钛板在上铜板在下的搭接连接。使用扫描电镜和能谱分析研究焊接接头的显微组织和反应界面金属间化合物的组成,并通过横向拉伸试验对接头的力学性能进行评定。研究结果表明,冷金属过渡技术可以实现于钛/铜异种金属的有效连接。焊接过程中电弧比较稳定,焊缝成形良好。在电弧热的作用下,铜板完全熔透,与焊缝金属形成铜-焊缝界面,钛板部分熔化,铜板和焊丝熔化包围在钛板的周围,形成了钛和焊缝的三个界面,提高了接头的力学性能。钛侧金属间化合物层包含TiCu、TiAl、Ti2Cu、AlCu2Ti和铜基固溶体等多种金属间化合物。拉伸试验时,断裂发生在铜母材的热影响区,拉剪强度可达200 MPa。
文摘运用相位摩擦焊技术实现电解铝阳极铝-钢的大端面焊接,替代了传统电解铝中铝-钢爆炸焊块作过渡的连接方式。在此主要研究了铝-钢摩擦焊接头的各项力学性能,并模拟真实电解环境对焊接件进行了电阻检测试验,试验结果表明:铝-钢摩擦焊接头可承受的最高平均负载为88 t,高于传统型接头59 t;温度350℃、通电电流7 k A条件下,铝-钢摩擦焊技术可实现降低阳极压降约8 m V。
