An innovative physical simulation apparatus, including high speed camera, red thermal imaging system, and mechanical quantity sensor, was used to investigate the friction heat generation and atom diffusion behavior du...An innovative physical simulation apparatus, including high speed camera, red thermal imaging system, and mechanical quantity sensor, was used to investigate the friction heat generation and atom diffusion behavior during Mg-Ti friction welding process. The results show that the friction coefficient mainly experiences two steady stages. The first steady stage corresponds to the Coulomb friction with material abrasion. The second steady stage corresponds to the stick friction with fully plastic flow. Moreover, the increasing rates of axial displacement, temperature and friction coefficient are obviously enhanced with the increase of rotation speed and axial pressure. It can also be found that the there exists rapid diffusion phenomenon in the Mg-Ti friction welding system. The large deformation activated diffusion coefficient is about 105 higher than that activated by thermal.展开更多
Aluminum alloys are subjected to large deformation and decreased strength due to the high expansion modulus caused by heat effects during friction stir welding （FSW）.The optimum conditions for friction stir welding ...Aluminum alloys are subjected to large deformation and decreased strength due to the high expansion modulus caused by heat effects during friction stir welding （FSW）.The optimum conditions for friction stir welding of 5052-O and 6061-T6 Al alloys were determined.The optimum traveling and rotation speeds were identified to be 61mm/min and 1600r/min using various mechanical characteristic evaluation methods.展开更多
A356 is a high strength aluminium-silicon cast alloy used in food,chemical,marine,electrical and automotive industries.Fusion welding of this cast alloy will lead to many problems such as porosity,micro-fissuring,and ...A356 is a high strength aluminium-silicon cast alloy used in food,chemical,marine,electrical and automotive industries.Fusion welding of this cast alloy will lead to many problems such as porosity,micro-fissuring,and hot cracking.However,friction stir welding（FSW） can be used to weld this cast alloy without above mentioned defects.An attempt was made to study the effect of FSW process parameters on the tensile strength of cast A356 aluminium alloy.Joints were made using different combinations of tool rotation speed,welding speed and axial force.The quality of weld zone was analyzed by macrostructure and microstructure analyses.Tensile strengths of the joints were evaluated and correlated with the weld zone hardness and microstructure.The joint fabricated using a rotational speed of 1000 r/min,a welding speed of 75 mm/min and an axial force of 5 kN showed a higher tensile strength compared to the other joints.展开更多
The friction stir lap welding of AISI304 stainless steel to AA7075 aluminium alloy was investigated using the conventional friction stir welding (C-FSW) and the reverse dual rotation friction stir welding (DR-FSW) pro...The friction stir lap welding of AISI304 stainless steel to AA7075 aluminium alloy was investigated using the conventional friction stir welding (C-FSW) and the reverse dual rotation friction stir welding (DR-FSW) processes. In order to reduce the heat input, a dual rotation tool with a lower shoulder rotating speed was used. The results showed that both processes provide welds with excellent appearance and free of internal defects. The use of the DR-FSW process with the tool shoulder rotating reversely at low speed results in larger grain refinement in the nugget and less change in the microstructure of the aluminium alloy than using the C-FSW. The use of DR-FSW process at low speed of rotation allows to reduce the amount of intermetallic compounds in the welding interface, but does not prevent their formation. Although DR-FSW welding exhibits tensile strength superior to that achieved with the conventional process (C-FSW), both exhibit brittle behaviour with fracture at the weld interface.展开更多
基金Projects (51101126, 51071123) supported by the National Natural Science Foundation of ChinaProjects (20110491684, 2012T50817) supported by the China Postdoctoral Science FoundationProject (20110942K) supported by the Open Fund of State Key Laboratory of Powder Metallurgy of Central South University, China
文摘An innovative physical simulation apparatus, including high speed camera, red thermal imaging system, and mechanical quantity sensor, was used to investigate the friction heat generation and atom diffusion behavior during Mg-Ti friction welding process. The results show that the friction coefficient mainly experiences two steady stages. The first steady stage corresponds to the Coulomb friction with material abrasion. The second steady stage corresponds to the stick friction with fully plastic flow. Moreover, the increasing rates of axial displacement, temperature and friction coefficient are obviously enhanced with the increase of rotation speed and axial pressure. It can also be found that the there exists rapid diffusion phenomenon in the Mg-Ti friction welding system. The large deformation activated diffusion coefficient is about 105 higher than that activated by thermal.
文摘Aluminum alloys are subjected to large deformation and decreased strength due to the high expansion modulus caused by heat effects during friction stir welding （FSW）.The optimum conditions for friction stir welding of 5052-O and 6061-T6 Al alloys were determined.The optimum traveling and rotation speeds were identified to be 61mm/min and 1600r/min using various mechanical characteristic evaluation methods.
文摘A356 is a high strength aluminium-silicon cast alloy used in food,chemical,marine,electrical and automotive industries.Fusion welding of this cast alloy will lead to many problems such as porosity,micro-fissuring,and hot cracking.However,friction stir welding（FSW） can be used to weld this cast alloy without above mentioned defects.An attempt was made to study the effect of FSW process parameters on the tensile strength of cast A356 aluminium alloy.Joints were made using different combinations of tool rotation speed,welding speed and axial force.The quality of weld zone was analyzed by macrostructure and microstructure analyses.Tensile strengths of the joints were evaluated and correlated with the weld zone hardness and microstructure.The joint fabricated using a rotational speed of 1000 r/min,a welding speed of 75 mm/min and an axial force of 5 kN showed a higher tensile strength compared to the other joints.
基金funding support of Babol Noshirvani University of Technology(No.BNUT/370167/97)support of programme COMPETE+1 种基金Programa Operacional Factores de CompetitividadeFCT-Fundacao Portuguesa para a Ciência e a Tecnologia,under the project UID/EMS/00285/2013.
文摘The friction stir lap welding of AISI304 stainless steel to AA7075 aluminium alloy was investigated using the conventional friction stir welding (C-FSW) and the reverse dual rotation friction stir welding (DR-FSW) processes. In order to reduce the heat input, a dual rotation tool with a lower shoulder rotating speed was used. The results showed that both processes provide welds with excellent appearance and free of internal defects. The use of the DR-FSW process with the tool shoulder rotating reversely at low speed results in larger grain refinement in the nugget and less change in the microstructure of the aluminium alloy than using the C-FSW. The use of DR-FSW process at low speed of rotation allows to reduce the amount of intermetallic compounds in the welding interface, but does not prevent their formation. Although DR-FSW welding exhibits tensile strength superior to that achieved with the conventional process (C-FSW), both exhibit brittle behaviour with fracture at the weld interface.
