This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of lo...This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of low carbon steel were processed firstly by laser cladding with Fe-based alloy powders and then by electrospark deposition with WC-SCo cemented carbide. It is shown that, for these two treatments, the electrospark coating possesses finer microstructure than the laser coating, and the thickness and surface hardness of the electrospark coating can be substantially increased.展开更多
Ni60-WC particles are used to improve the wear resistance of hard-facing steel due to their high hardness. An emerging technology that combines laser with cold spraying to deposit the hard-facing coatings is known as ...Ni60-WC particles are used to improve the wear resistance of hard-facing steel due to their high hardness. An emerging technology that combines laser with cold spraying to deposit the hard-facing coatings is known as supersonic laser deposition. In this study, Ni60-WC is deposited on low-carbon steel using SLD. The microstructure and performance of the coatings are investigated through SEM, optical microscopy, EDS, XRD, microhardness and pin-on-disc wear tests. The experimental results of the coating processed with the optimal parameters are compared to those of the coating deposited using laser cladding.展开更多
Laser micro cladding deposition manufacturing(Ll CDM) is a newly developed rapid manufacturing method for metals.The Ll CDM technology adopts a novel powder feeding method based on alternating friction and inertia for...Laser micro cladding deposition manufacturing(Ll CDM) is a newly developed rapid manufacturing method for metals.The Ll CDM technology adopts a novel powder feeding method based on alternating friction and inertia force, and this powder feeding method can effectively improve the accuracy and orientation of the powder injection, resulting in a smaller molten pool size and a higher cooling rate of liquid metal.Therefore, the components fabricated by Ll CDM could obtain the finer microstructures and the improved mechanical properties.It is found that the components fabricated by Ll CDM are fully dense free of cracks or pores and exhibit columnar prior b grains with a finer acicular a0 phase microstructure.The microhardness(HV0.2) of the thin-wall component is HV 400–HV 500 in the majority part of the cross section and can reach about HV 850 in the top region.The ultimate tensile strength(UTS) and elongation show insignificant dependence on the testing directions of the tensilespecimens.The UTS is between 1,002 and 1,100 MPa, and the elongation is between 10.0 % and 14.7 %.展开更多
Laser cladding deposited Ti-6Al-4V titanium alloy universally shows more complex microstructures,each of which has significant effect on mechanical properties. Of particular α/β interface phase has been observed in ...Laser cladding deposited Ti-6Al-4V titanium alloy universally shows more complex microstructures,each of which has significant effect on mechanical properties. Of particular α/β interface phase has been observed in this paper under certain conditions. It demonstrates that the influence of the α/β interface phase on the tensile properties is closely associated with dislocations and twin substructure through comparison experiments. The results show that the α/β interface phase hinders dislocation motion and decreases effective slip length. In addition, the twin substructure has been activated in the α/β interface phase during tensile process and has acted somehow like grain boundaries. Therefore, the strength and the work-hardening rate of the laser cladding deposited Ti-6Al-4V titanium alloy have been significantly improved due to the dynamic Hall-Petch effect. Besides, the α/β interface phase leads to more uniform dislocations distribution, which implies that relative lower local concentrated stress will be produced along the α/β interface phase or colony boundary after the same amount of plastic deformation. Moreover,the twinning-induced plasticity effects in the α/β interface phase further increase the plastic deformation capacity. These results in higher elongation for the laser cladding deposited Ti-6Al-4V titanium alloy.It can be concluded that the current work suggests an effective method to simultaneously improve the strength and plasticity of laser cladding deposited Ti-6Al-4V titanium alloy based on the α/β interface phase.展开更多
Recent advances in laser coating technology including laser cladding,laser surface alloying and laser vapour deposition in China are reviewed in this paper.
文摘This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of low carbon steel were processed firstly by laser cladding with Fe-based alloy powders and then by electrospark deposition with WC-SCo cemented carbide. It is shown that, for these two treatments, the electrospark coating possesses finer microstructure than the laser coating, and the thickness and surface hardness of the electrospark coating can be substantially increased.
基金sponsored by the Centre for Industrial Photonics, Institute for Manufacture, Department of Engineering, University of Cambridgethe Natural Science Foundation of China (51271170)+1 种基金China International Science and Technology Cooperation Project (2011DFR50540)Major Scientific and Technological Special Key Industrial Project of Zhejiang Province (2012C11001)
文摘Ni60-WC particles are used to improve the wear resistance of hard-facing steel due to their high hardness. An emerging technology that combines laser with cold spraying to deposit the hard-facing coatings is known as supersonic laser deposition. In this study, Ni60-WC is deposited on low-carbon steel using SLD. The microstructure and performance of the coatings are investigated through SEM, optical microscopy, EDS, XRD, microhardness and pin-on-disc wear tests. The experimental results of the coating processed with the optimal parameters are compared to those of the coating deposited using laser cladding.
基金financially supported by the National Natural Science Foundation of China (No. 50975152)
文摘Laser micro cladding deposition manufacturing(Ll CDM) is a newly developed rapid manufacturing method for metals.The Ll CDM technology adopts a novel powder feeding method based on alternating friction and inertia force, and this powder feeding method can effectively improve the accuracy and orientation of the powder injection, resulting in a smaller molten pool size and a higher cooling rate of liquid metal.Therefore, the components fabricated by Ll CDM could obtain the finer microstructures and the improved mechanical properties.It is found that the components fabricated by Ll CDM are fully dense free of cracks or pores and exhibit columnar prior b grains with a finer acicular a0 phase microstructure.The microhardness(HV0.2) of the thin-wall component is HV 400–HV 500 in the majority part of the cross section and can reach about HV 850 in the top region.The ultimate tensile strength(UTS) and elongation show insignificant dependence on the testing directions of the tensilespecimens.The UTS is between 1,002 and 1,100 MPa, and the elongation is between 10.0 % and 14.7 %.
基金supported by the National Key Research And Development Plan, China (No. 2016YFB1100100)the Research Fund of the State Key Laboratory of Solidification Processing (NWPU), China (No. KP201611)the National Natural Science Foundation of China (No. 51475380)
文摘Laser cladding deposited Ti-6Al-4V titanium alloy universally shows more complex microstructures,each of which has significant effect on mechanical properties. Of particular α/β interface phase has been observed in this paper under certain conditions. It demonstrates that the influence of the α/β interface phase on the tensile properties is closely associated with dislocations and twin substructure through comparison experiments. The results show that the α/β interface phase hinders dislocation motion and decreases effective slip length. In addition, the twin substructure has been activated in the α/β interface phase during tensile process and has acted somehow like grain boundaries. Therefore, the strength and the work-hardening rate of the laser cladding deposited Ti-6Al-4V titanium alloy have been significantly improved due to the dynamic Hall-Petch effect. Besides, the α/β interface phase leads to more uniform dislocations distribution, which implies that relative lower local concentrated stress will be produced along the α/β interface phase or colony boundary after the same amount of plastic deformation. Moreover,the twinning-induced plasticity effects in the α/β interface phase further increase the plastic deformation capacity. These results in higher elongation for the laser cladding deposited Ti-6Al-4V titanium alloy.It can be concluded that the current work suggests an effective method to simultaneously improve the strength and plasticity of laser cladding deposited Ti-6Al-4V titanium alloy based on the α/β interface phase.
文摘Recent advances in laser coating technology including laser cladding,laser surface alloying and laser vapour deposition in China are reviewed in this paper.
