The laser-cladding technique for welding of bridge wires is reported for the first time.The essen- tial feature of this technique different from the cur- rent methods is the realization of mutual melting of workpieces...The laser-cladding technique for welding of bridge wires is reported for the first time.The essen- tial feature of this technique different from the cur- rent methods is the realization of mutual melting of workpieces.Thus the stability of products is im- proved in an order of magnitude.The main points of the technique and the microanalyses of the weld- ing spot and other features are given.The technique presented is a novel method of welding between tiny piece and workpiece of different sizes and proper- ties.展开更多
Effect of laser scanning speed on phase constitution,microstructure,microhardness and wear resistance of laser-cladding hard facing alloy Stellite 12 has been investigated by means of a cross-flow-type CO_2 laser of 1...Effect of laser scanning speed on phase constitution,microstructure,microhardness and wear resistance of laser-cladding hard facing alloy Stellite 12 has been investigated by means of a cross-flow-type CO_2 laser of 1.5 kW.The laser-cladding layer on the alloy consists of ma- trix phase of suppersaturated solid solution γ(Co,Cr)and complex hexagonal carbide M_7C_3.Under certain condition,at higher laser scanning speed,the suppersaturated solubility of elements increases in γ(Co,Cr),and the precipitation of the complex carbtde M_7C_3 de- creases,so the microhardness increases and the wear resistance decreases.But at slower laser scanning speed,more complex carbide M_7C_3 may precipitate,and the wear resistance may be improved.Therefore,it is believed that the principal factor in improving wear resistance is the precipitation of carbide M_7C_3,while increment of microhardness is the suppersaturated solu- bility of elements in matrix phase γ(Co,Cr).展开更多
An Al-Si/Al+Al2O3 coating was prepared on an AZ91D Mg alloy substrate by laser cladding of the plasma-sprayed coating.X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the phases and...An Al-Si/Al+Al2O3 coating was prepared on an AZ91D Mg alloy substrate by laser cladding of the plasma-sprayed coating.X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the phases and to study the morphology,respectively.The adhesion strength and the porosity ratio of the coating were measured by using a tensile testing machine and an optical microscope (OM),respectively.The microhardness was measured using a micro Vickers hardness tester.The results show that after laser cladding,the adhesion strength of the coating increased from 10.78 to 25.17 MPa.When the laser power was 1400W,the metastable γ-Al2O3 phase in the coating transformed completely into the stable α-Al2O3 phase.Along with the increase of the laser power,the porosity ratio of the coating decreased.But when the laser power was over 1400W,the porosity ratio increased.The microhardness of the surface was the hardest which was improved from HV0.05125 to HV0.05221.The larger the power of the laser was,the harder the coating was.But when the power was 1600W,the microhardness increased slightly,even the microhardness of the internal decreased.展开更多
文摘The laser-cladding technique for welding of bridge wires is reported for the first time.The essen- tial feature of this technique different from the cur- rent methods is the realization of mutual melting of workpieces.Thus the stability of products is im- proved in an order of magnitude.The main points of the technique and the microanalyses of the weld- ing spot and other features are given.The technique presented is a novel method of welding between tiny piece and workpiece of different sizes and proper- ties.
文摘Effect of laser scanning speed on phase constitution,microstructure,microhardness and wear resistance of laser-cladding hard facing alloy Stellite 12 has been investigated by means of a cross-flow-type CO_2 laser of 1.5 kW.The laser-cladding layer on the alloy consists of ma- trix phase of suppersaturated solid solution γ(Co,Cr)and complex hexagonal carbide M_7C_3.Under certain condition,at higher laser scanning speed,the suppersaturated solubility of elements increases in γ(Co,Cr),and the precipitation of the complex carbtde M_7C_3 de- creases,so the microhardness increases and the wear resistance decreases.But at slower laser scanning speed,more complex carbide M_7C_3 may precipitate,and the wear resistance may be improved.Therefore,it is believed that the principal factor in improving wear resistance is the precipitation of carbide M_7C_3,while increment of microhardness is the suppersaturated solu- bility of elements in matrix phase γ(Co,Cr).
基金Foundation item:Project(20085451039)supported by the Aeronautical Foundation of China
文摘An Al-Si/Al+Al2O3 coating was prepared on an AZ91D Mg alloy substrate by laser cladding of the plasma-sprayed coating.X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the phases and to study the morphology,respectively.The adhesion strength and the porosity ratio of the coating were measured by using a tensile testing machine and an optical microscope (OM),respectively.The microhardness was measured using a micro Vickers hardness tester.The results show that after laser cladding,the adhesion strength of the coating increased from 10.78 to 25.17 MPa.When the laser power was 1400W,the metastable γ-Al2O3 phase in the coating transformed completely into the stable α-Al2O3 phase.Along with the increase of the laser power,the porosity ratio of the coating decreased.But when the laser power was over 1400W,the porosity ratio increased.The microhardness of the surface was the hardest which was improved from HV0.05125 to HV0.05221.The larger the power of the laser was,the harder the coating was.But when the power was 1600W,the microhardness increased slightly,even the microhardness of the internal decreased.
