Effect Of Powder Cycles On Selective Laser Melting Of AlSi10Mg Alloy

Selective Lazer Melting(SLM)is a new-type metal Additive Manufacturing(AM)technology,with high mechanical properties and good density being the feature of its formed samples,the development of SLM forming technology,however,is deeply affected by high cost of raw materials and process parameters.Thus,there is a need to determine the process evolution of the powder with different times of recycling,and the structure and properties of large-thickness forming parts prepared by using reasonable process parameters while reducing the cost of raw materials and improving the forming efficiency and quality of the formed parts.Therefore,this paper,by taking the forming of AlSi10Mg alloy as an instance,carries out a study of SLM forming process and powder recycling times on the influence of the process evolution of the powder and the quality of formed parts.Firstly,the SLM forming process parameters of AlSi10Mg alloy with large layer thickness were optimized by orthogonal experimental design.As the processing parameters were: laser power 310 W,scan speed 1450 mm/s,scan spacing 95 μm,and coating thickness 60 μm,the sample density was up to 99.90%,and the forming efficiency was 8.265 mm3/s,both of which reached a higher level.Secondly,in view of AlSi10Mg alloy with large layer thickness,the deformation of powder properties during recycling were studied by adopting characterization methods such as field emission Scanning Electron Microscope(SEM),powder properties multi-function tester and X-ray diffractometer,and the result showed: with the increase of recycling times of AlSi10Mg alloy powder,the change process of the surface to pography of recycling powder was: rough-smooth-rough,the proportion of small particles decreased,the particle size of 15 times recycling powder was larger than that of the original powder,and the particle size distribution was more dispersed.The apparent density and tap density of alloy powder increased at first and then decreased.Meanwhile,with the increase of recycling times,the angle of repose and angle of collapse of powder decreased gradually,while the angle of difference and oxygen content increased obviously;The flowability of powder increased gradually after multiple recycling,and reached the best when the powder was recycled for 15 times.Finally,the microstructure changes of AlSi10Mg alloy with large layer thickness samples with different recycling times were observed by means of metallographic microscope and field emission scanning electron microscope,and the mechanical properties of AlSi10Mg alloy with large layer thickness samples with different recycling times were tested by microhardness test and tensile test,and the result showed:the particle size distribution and surface topography of the original powder changed after 15 times recycling,the number and size of holes in the metallographic structure of the formed sample increased slightly,which led to a slight decrease in the density of the formed part;when the number of powder recycling was less than 10 times,no significant difference had been shown in the mechanical properties of the large layer thickness formed part prepared by the original powder and recycling powder,however,as the number of powder recycling reached 15 times,the tensile strength and microhardness of the formed part were slightly reduced because of the large porosity of the samples.In a word,with the increase of powder recycling times,slight changes in microstructure and mechanical properties of AlSi10Mg alloy with large layer thickness prepared by original powder to 15 times recycling powder did not cause the deterioration of the quality and properties of the alloy samples.