AA5454-O aluminum alloy plates with the thicknesses of 1.4 and 1.0 mm were friction-spot-joined (FSJed).The plunge speed of the joining tool was changed in a range of 100 500 mm/min under a constant rotation speed of ...AA5454-O aluminum alloy plates with the thicknesses of 1.4 and 1.0 mm were friction-spot-joined (FSJed).The plunge speed of the joining tool was changed in a range of 100 500 mm/min under a constant rotation speed of 500 r/min.The plunge depth was ranged from 1.6 mm to 2.2 mm.The tool plunge speed did not make a remarkable effect on the surface appearance and macro-structure of the FSJed zone.The average hardness of the FSJed zone was greater than or equal to that of the base metal.However,there was no remarkable tendency in the average hardness change of the FSJed zone in spite of the variation in the tool plunge speed and tool plunge depth.The increase of the tool plunge depth resulted in the increase of the tensile shear load.However,the change of the tool plunge speed did not lead to the remarkable variation in the tensile shear load of the FSJed plates.It was noteworthy that the FSJed plate exhibited the highest tensile shear load of about 4.0 kN.展开更多
Friction stir spot welding of A6061 sheets was conducted using a tool with thread pin. The hook geometries, hook formation and mechanical properties of the joints welded with different rotary directions and speeds wer...Friction stir spot welding of A6061 sheets was conducted using a tool with thread pin. The hook geometries, hook formation and mechanical properties of the joints welded with different rotary directions and speeds were investigated. The results show that the hook in the joint welded in clockwise was curved upwards and that in anticlockwise was curved downwards. The hook formation was related to the plastic material flow in the joint. With increasing the rotary speed in clockwise direction, the hook moved upwards and far way from the center of the keyhole, resulting in an increase in the effective weld width and a decrease in the effective sheet thickness. Three types of fractuces were observed and they were affected by the hook geometries. The tensile shear load increased firstly and then decreased when the rotary speed increased in clockwise direction, which was related to the hook geometries.展开更多
The weld nugget formation in the resistance spot welding(RSW) of aluminum alloy was investigated in the present study. The nugget formation process was directly observed by using a digital high-speed camera. Numerical...The weld nugget formation in the resistance spot welding(RSW) of aluminum alloy was investigated in the present study. The nugget formation process was directly observed by using a digital high-speed camera. Numerical simulation was also employed to investigate the nugget formation process. The results showed that for the RSW of two aluminum alloy sheets, a nugget was first formed in the workpiece/workpiece(W/W) interface and grew along the radial direction and axial direction of the sheets, and then it became a large elliptical nugget. For the RSW of three aluminum alloy sheets, two small nuggets were firstly formed in two W/W interfaces and grew along the axial direction and radial direction; finally they fused into one nugget. Besides, there existed a critical welding time, after which the nugget size remained nearly unchanged. This indicates that a long welding time is unnecessary for the RSW of aluminum alloy. In addition, the calculated nugget radius was compared with the experimental results, which showed that the simulation results agreed well with the experimental results.展开更多
采用高速摄影和光谱诊断的方法研究了真空弧离子源脉冲工作瞬间的放电行为。拍摄了离子源放电瞬间吸氢电极上阴极斑的形成过程,分析了不同放电电流时阴极斑的发射光谱。实验结果表明,当脉冲工作电流为 101—102 A 时,真空弧离子源放电...采用高速摄影和光谱诊断的方法研究了真空弧离子源脉冲工作瞬间的放电行为。拍摄了离子源放电瞬间吸氢电极上阴极斑的形成过程,分析了不同放电电流时阴极斑的发射光谱。实验结果表明,当脉冲工作电流为 101—102 A 时,真空弧离子源放电区一般只有单个阴极斑,阴极斑的位置在同一次放电中的变化很小;较大的脉冲工作电流有利于提高阴极斑的温度,并最终导致氢离子浓度的增加,但也会使阴极材料的溅射更加严重,造成离子源等离子体品质下降。展开更多
基金financially supported by the Ministry of Education,Science Technology(MEST)and National Research Foundation of Korea(NRF)through the Human Resource Training Project for Regional Innovationby the development program of local science park funded by the ULSAN Metropolitan City and the Ministry of Education,Science and Technology(MEST)
文摘AA5454-O aluminum alloy plates with the thicknesses of 1.4 and 1.0 mm were friction-spot-joined (FSJed).The plunge speed of the joining tool was changed in a range of 100 500 mm/min under a constant rotation speed of 500 r/min.The plunge depth was ranged from 1.6 mm to 2.2 mm.The tool plunge speed did not make a remarkable effect on the surface appearance and macro-structure of the FSJed zone.The average hardness of the FSJed zone was greater than or equal to that of the base metal.However,there was no remarkable tendency in the average hardness change of the FSJed zone in spite of the variation in the tool plunge speed and tool plunge depth.The increase of the tool plunge depth resulted in the increase of the tensile shear load.However,the change of the tool plunge speed did not lead to the remarkable variation in the tensile shear load of the FSJed plates.It was noteworthy that the FSJed plate exhibited the highest tensile shear load of about 4.0 kN.
基金This work was sponsored by the National Natural Science Foundation of China （51364037）, the Landed Plan of Science and Technology in Colleges and Universities of Jiangxi Province （KJLD12074）, the Aerospace Science Foundation of China （20111156004）.
文摘Friction stir spot welding of A6061 sheets was conducted using a tool with thread pin. The hook geometries, hook formation and mechanical properties of the joints welded with different rotary directions and speeds were investigated. The results show that the hook in the joint welded in clockwise was curved upwards and that in anticlockwise was curved downwards. The hook formation was related to the plastic material flow in the joint. With increasing the rotary speed in clockwise direction, the hook moved upwards and far way from the center of the keyhole, resulting in an increase in the effective weld width and a decrease in the effective sheet thickness. Three types of fractuces were observed and they were affected by the hook geometries. The tensile shear load increased firstly and then decreased when the rotary speed increased in clockwise direction, which was related to the hook geometries.
基金Supported by the National Natural Science Foundation of China(No.51275342 and No.51275338)
文摘The weld nugget formation in the resistance spot welding(RSW) of aluminum alloy was investigated in the present study. The nugget formation process was directly observed by using a digital high-speed camera. Numerical simulation was also employed to investigate the nugget formation process. The results showed that for the RSW of two aluminum alloy sheets, a nugget was first formed in the workpiece/workpiece(W/W) interface and grew along the radial direction and axial direction of the sheets, and then it became a large elliptical nugget. For the RSW of three aluminum alloy sheets, two small nuggets were firstly formed in two W/W interfaces and grew along the axial direction and radial direction; finally they fused into one nugget. Besides, there existed a critical welding time, after which the nugget size remained nearly unchanged. This indicates that a long welding time is unnecessary for the RSW of aluminum alloy. In addition, the calculated nugget radius was compared with the experimental results, which showed that the simulation results agreed well with the experimental results.
文摘采用高速摄影和光谱诊断的方法研究了真空弧离子源脉冲工作瞬间的放电行为。拍摄了离子源放电瞬间吸氢电极上阴极斑的形成过程,分析了不同放电电流时阴极斑的发射光谱。实验结果表明,当脉冲工作电流为 101—102 A 时,真空弧离子源放电区一般只有单个阴极斑,阴极斑的位置在同一次放电中的变化很小;较大的脉冲工作电流有利于提高阴极斑的温度,并最终导致氢离子浓度的增加,但也会使阴极材料的溅射更加严重,造成离子源等离子体品质下降。
