Plasma-MIG {metal inert gas arc welding） hybrid welding of aluminum alloy with 6 mm thickness using ER5356 welding wire was carried out. The microstructures and mechanical properties of the welded joint were inve...Plasma-MIG {metal inert gas arc welding） hybrid welding of aluminum alloy with 6 mm thickness using ER5356 welding wire was carried out. The microstructures and mechanical properties of the welded joint were investigated by optical microscopy, X-ray diffraction （XRD） , energy dispersive spectroscopy （EDS） , tensile test, hardness test and scanning electron microscope （ SEM） were used to judge the type of tensile fracture. The results showed that the tensile strength of welded joint was 142 MPa which was 53. 6% o f the strength o f the base metal. The welding seam zone was characterized by dendritic structure. In the fusion zone, the columnar grains existed at one side of the welding seam. The fibrous organization was found in the base metal, and also in the heat affected zone （HAZ） where the recrystallization occurred. The HAZ was the weakest position of the welded joint due to the coarsening of Mg2Si phase. The type of tensile fracture was ductile fracture.展开更多
Arc spectral information is a rising information source which can solve manyproblems that can not be done with arc electric information and other arc information. It is ofimportant significance to develop automatic co...Arc spectral information is a rising information source which can solve manyproblems that can not be done with arc electric information and other arc information. It is ofimportant significance to develop automatic control technique of welding process. The basic theoryand methods on it play an important role in expounding and applying arc spectral information. Usingconcerned equation in plasma physics and spectrum theory, a system of equations including 12equations which serve as basic theory of arc spectral information is set up. Through analyzing ofthe 12 equations, a basic view that arc spectral information is the reflection of arc state andstate variation, and is the most abundant information resource reflecting welding arc process isdrawn. Furthermore, based on the basic theory, the basic methods of test and control of arc spectralinformation and points out some applications of it are discussesed.展开更多
Ni-based composite coatings with a high content of tungsten carbides(Stelcar65composite coatings)were synthesized by plasma transferred arc(PTA)hardfacing.The welding parameters of Stelcar65composite coatings were opt...Ni-based composite coatings with a high content of tungsten carbides(Stelcar65composite coatings)were synthesized by plasma transferred arc(PTA)hardfacing.The welding parameters of Stelcar65composite coatings were optimized by orthogonal tests.The PTA welding parameters including welding current,powder feed rate and welding speed have significant influence on the tungsten carbide degradation.The values for the optimum welding current,powder feed rate and welding speed were determined to be100A,25g/min and40mm/min,respectively.The produced WC/Ni-based composite coatings were crack-and degradation-free.The microstructure of deposited layers,as well as the microstructure and microhardness of the optimal coating were further analyzed.展开更多
The effect of Ti-Al on microstructures and mechanical properties of SiCp/Al MMC joints produced by plasma arc in-situ weld-alloying was investigated, in which argon-nitrogen mixture was used as plasma gases and Ti-Al ...The effect of Ti-Al on microstructures and mechanical properties of SiCp/Al MMC joints produced by plasma arc in-situ weld-alloying was investigated, in which argon-nitrogen mixture was used as plasma gases and Ti-Al alloy as filling composite. The results show that the formation of needle-like harmful phase Al4C3 is effectively prevented in the weld by in-situ weld-alloying/plasma arc welding with Ti-Al alloy sheet filler whose titanium content is more than 20%. The fluidity of molten pool is improved, and stable molten pool is gained for the addition of the Ti-Al alloy. The mechanical properties of welded joint are effectively enhanced by the compact-grain structure and the new reinforced composites such as Al3Ti, TiN, AlN and TiC welded joint. The test results of mechanical property show that the maximum tensile strength of welded joint gained by adding Ti-60Al alloy is up to 235 MPa. The factors influencing the tensile strength were also investigated.展开更多
The plasma-MIG welding torch was developed.5A06 aluminum alloys with V-grooves were welded in a single pass in the plasma-MIG welding process and the joints were examined by X-ray diffractometry analysis and mechanica...The plasma-MIG welding torch was developed.5A06 aluminum alloys with V-grooves were welded in a single pass in the plasma-MIG welding process and the joints were examined by X-ray diffractometry analysis and mechanical tests.The orthogonal experimental design was used to study the influence of plasma-MIG welding parameters on the aluminum weld porosity.The mixed orthogonal matrix L16(4 4×2 3) and analysis of variance (ANOVA)technique were employed to optimize the welding parameters.The experimental results indicate that the effect of plasma gas flow rate is dominant,the secondary factors are MIG welding voltage,welding speed,wire feed rate and plasma current in turn.Confirmation experiments were conducted under optimum conditions and there was almost no porosity in the welded joints,thus good mechanical performance joints were obtained.展开更多
A new kind of plasma technology with both high deposition rate and low dilution ratio was developed under the calculation and analysis of the arc flame characteristics of plasma arc,the kinematics behavior of powder a...A new kind of plasma technology with both high deposition rate and low dilution ratio was developed under the calculation and analysis of the arc flame characteristics of plasma arc,the kinematics behavior of powder and powder's heating in the arc. Compared with normal plasma surfacing method, the idea using constricting nozzle with small orifice diameter, long plasma arc and increasing the distance from meeting point of the two beams of powder to workpiece, to achieve the goals of high deposition rate and low dilution ratio, was put forward here. In order to prove this idea, a set of experimental system was built up and obtained satisfied results including high deposition rate(more than 25 kg/h )and low dilution ratio(less than 5%). The success of this study offers a promising prospect for developing the powder plasma surface welding in China and may open a way to improve this technology further in efficiency and quality.展开更多
基金Key Laboratory of Advanced Welding Technology of Jiangsu University of Science and Technology (Grant NO. JSAWT-11-02) for its financial support
文摘Plasma-MIG {metal inert gas arc welding） hybrid welding of aluminum alloy with 6 mm thickness using ER5356 welding wire was carried out. The microstructures and mechanical properties of the welded joint were investigated by optical microscopy, X-ray diffraction （XRD） , energy dispersive spectroscopy （EDS） , tensile test, hardness test and scanning electron microscope （ SEM） were used to judge the type of tensile fracture. The results showed that the tensile strength of welded joint was 142 MPa which was 53. 6% o f the strength o f the base metal. The welding seam zone was characterized by dendritic structure. In the fusion zone, the columnar grains existed at one side of the welding seam. The fibrous organization was found in the base metal, and also in the heat affected zone （HAZ） where the recrystallization occurred. The HAZ was the weakest position of the welded joint due to the coarsening of Mg2Si phase. The type of tensile fracture was ductile fracture.
基金This project is supported by National Natural Science Foundation of China(No.59975068) and Municipal Natural Science Foundation of Tianjin Municipal(No.99360291).
文摘Arc spectral information is a rising information source which can solve manyproblems that can not be done with arc electric information and other arc information. It is ofimportant significance to develop automatic control technique of welding process. The basic theoryand methods on it play an important role in expounding and applying arc spectral information. Usingconcerned equation in plasma physics and spectrum theory, a system of equations including 12equations which serve as basic theory of arc spectral information is set up. Through analyzing ofthe 12 equations, a basic view that arc spectral information is the reflection of arc state andstate variation, and is the most abundant information resource reflecting welding arc process isdrawn. Furthermore, based on the basic theory, the basic methods of test and control of arc spectralinformation and points out some applications of it are discussesed.
基金Project (2016YFB0300502) supported by the National Key Research and Development Program of ChinaProjects (51601129,51775386) supported by the National Natural Science Foundation of China+2 种基金Project (16PJ1410000) supported by Shanghai Pujiang Program,ChinaProject (16ZR1438700) supported by the Natural Science Foundation of Shanghai,ChinaProject (TPL1706) supported by Traction Power State Key Laboratory of Southwest Jiaotong University,China
文摘Ni-based composite coatings with a high content of tungsten carbides(Stelcar65composite coatings)were synthesized by plasma transferred arc(PTA)hardfacing.The welding parameters of Stelcar65composite coatings were optimized by orthogonal tests.The PTA welding parameters including welding current,powder feed rate and welding speed have significant influence on the tungsten carbide degradation.The values for the optimum welding current,powder feed rate and welding speed were determined to be100A,25g/min and40mm/min,respectively.The produced WC/Ni-based composite coatings were crack-and degradation-free.The microstructure of deposited layers,as well as the microstructure and microhardness of the optimal coating were further analyzed.
基金Project(50475126) supported by the National Natural Science Foundation of ChinaProject(JSAWT-07-04) supported by Key Lab of Jiangsu Province for Advanced Joining Technology, China
文摘The effect of Ti-Al on microstructures and mechanical properties of SiCp/Al MMC joints produced by plasma arc in-situ weld-alloying was investigated, in which argon-nitrogen mixture was used as plasma gases and Ti-Al alloy as filling composite. The results show that the formation of needle-like harmful phase Al4C3 is effectively prevented in the weld by in-situ weld-alloying/plasma arc welding with Ti-Al alloy sheet filler whose titanium content is more than 20%. The fluidity of molten pool is improved, and stable molten pool is gained for the addition of the Ti-Al alloy. The mechanical properties of welded joint are effectively enhanced by the compact-grain structure and the new reinforced composites such as Al3Ti, TiN, AlN and TiC welded joint. The test results of mechanical property show that the maximum tensile strength of welded joint gained by adding Ti-60Al alloy is up to 235 MPa. The factors influencing the tensile strength were also investigated.
文摘The plasma-MIG welding torch was developed.5A06 aluminum alloys with V-grooves were welded in a single pass in the plasma-MIG welding process and the joints were examined by X-ray diffractometry analysis and mechanical tests.The orthogonal experimental design was used to study the influence of plasma-MIG welding parameters on the aluminum weld porosity.The mixed orthogonal matrix L16(4 4×2 3) and analysis of variance (ANOVA)technique were employed to optimize the welding parameters.The experimental results indicate that the effect of plasma gas flow rate is dominant,the secondary factors are MIG welding voltage,welding speed,wire feed rate and plasma current in turn.Confirmation experiments were conducted under optimum conditions and there was almost no porosity in the welded joints,thus good mechanical performance joints were obtained.
文摘A new kind of plasma technology with both high deposition rate and low dilution ratio was developed under the calculation and analysis of the arc flame characteristics of plasma arc,the kinematics behavior of powder and powder's heating in the arc. Compared with normal plasma surfacing method, the idea using constricting nozzle with small orifice diameter, long plasma arc and increasing the distance from meeting point of the two beams of powder to workpiece, to achieve the goals of high deposition rate and low dilution ratio, was put forward here. In order to prove this idea, a set of experimental system was built up and obtained satisfied results including high deposition rate(more than 25 kg/h )and low dilution ratio(less than 5%). The success of this study offers a promising prospect for developing the powder plasma surface welding in China and may open a way to improve this technology further in efficiency and quality.
