Experimental Study On Metal 3D Printing Overhanging Structure And High Efficient Forming Process

Selective Laser Melting(SLM)is a kind of additive manufacturing technology with broad development prospects.The laser beam and metal powder is used as manufacturing tools,the tools and fixtures required is eliminated,so the processing cycle is greatly shortened.The SLM forming technology can directly produce metal parts with metallurgical bonding,high relative density,excellent mechanical properties,high dimensional accuracy and excellent surface quality.In the SLM forming,the difficulty in forming the suspension structure and the low forming efficiency restrict its application and development.Therefore,this paper mainly conducts the following research through the combination of experimental research and theoretical analysis:(1)Foundation process experience and research to find high-quality forming optimization process.Using TiAl alloy powders,the effects of various processes on crack suppression in forming process were studied by using auxiliary processes such as preheating,pre-sintering and remelting of substrates at different temperatures,and the 3D printing experiments of single track and Multi-layer experiences were carried out.(2)An experimental study was carried out on a suspension structure which is difficult to form by optimizing the process.The effects of laser power on the forming quality of 316L stainless steel and Ni-Cr alloy steel at different forming angles were studied,and the effects of different scanning strategies,surface remelting optimization and boundary scanning optimization on the forming of suspension structure were compared.(3)The forming efficiency can be improved by increasing the thickness or increasing the rate of formation,and the forming surface can be optimized by optimizing the process.The experimental study on large-thickness and high-speed forming of 316L stainless steel by selective laser melting was carried out.By narrowing the technological window of single melting channel,the technological parameters of high density Multi-layer forming and the forming principle of defects were explored,and the microstructures and mechanical properties were observed and analyzed in depth.