Forming Processes And Microstructures And Properties Of W-Re Alloy By Selective Laser Melting

W and its alloys have many excellent properties,and have been widely used in aerospace,national defense,mineral exploitation,metal processing,oil drilling and other fields.At present,due to the high temperature strength and high melting point,the forming of metal W is a great challenge,so that most of the W parts were fabricated by powder metallurgy technology.With the requirements of more complex shapes and lower cost for refractory metals,the traditional powder metallurgy method is difficult to meet the requirement of today’s engineering.Selective laser melting（SLM）has become one of the most potential forming methods for W parts.In this paper,the SLM forming process,microstructures and properties of pure W and W-Re alloys were investigeted.The effects of processing parameters on the forming quality of pure W and W-Re alloy were studied by changing laser power,scan velocity and scan distance during the forming processes of SLM;The effect of 5wt%Re addition on the forming quality,microstructures and properties of SLM W alloy was emphasized on.The results were as follow:With proper matching of SLM process parameters,W and W-Re alloy parts with density more than 90%were obtained.The addition of 5wt%Re improved the microstructures and properties of the W-shaped parts prepared by selective laser melting.Surface morphology,the density,defects,hardness and corrosion resistance of the parts of pure W and W-Re alloy parts were compared under the same laser processing parameters.Under the same processing parameters,it is found that the addition of Re can improve the density and hardness of W-Re alloy parts with the highest density of 96.1%and the maximum hardness of 550HV,which is 20%higher than that of pure W part,The addition of Re in W is beneficial to the complete melting of the powder,reduce the holes and cracks in the selective laser melting process,and improve the microstructures of SLM parts;W-Re alloy has fewer cracks than pure W.No matter in 0.5mol/l H₂SO₄ solution or in 1mol/l Na OH solution,W-Re alloy has shown the better corrosion resistance than that of pure W.By changing the laser power,scanning speed and scanning distance,the properties of W and W-Re alloys changed greatly.Under the laser power of 180 W,combined with the scanning speed of 600 mm/s and the scanning distance of 0.03mm,the multiple performances of the parts were promoted.Within a certain range of parameters,the density and hardness of W-Re alloy parts increased with the increase of laser power,and decreased with the increase of scanning speed and scanning distance.The XRD pattern of W-Re alloy sample showed that the W diffraction peak shifted to the right.The higher the laser power was,the better the corrosion resistance of W-Re alloy sanmple had shown.