Study On The Processing Properties Of Selective Laser Melting Ti6Al4V

The products in Aerospace,medical equipment and other fields need long life,high safety performance,but also to meet the high strength,lightweight requirements.This is often on the product's own material and structure has a high technical requirements.Titanium Alloy is a new type of alloy material,which is wear-resisting,corrosion-resisting,light weight and high strength,which have a very high application prospects in these areas.It can be directly melted and cooled to form metal parts with complex structure and difficult to machine,high manufacturing speed and small product development cycle.It's perfect for titanium alloys.In this paper,Ti6Al4V(TC4)was used as research material.Studied the forming process and process optimization of TC4 titanium alloy prepared by SLM.Described the crack morphology and mechanism of TC4 titanium alloy sample formed by SLM,and the cracks suppression scheme was proposed and verified by experiment.This research is expected to be the basis and technical basis for the formation of TC4 titanium alloy with high performance and complex structure by SLM.The specific conclusions are as follows:(1)The SLM forming process parameters of TC4 alloy were optimized.The results showed that the quality and morphology of the parts are directly affected by the different process parameters.When the laser power is 190 W ? 250 W,the scanning speed is 600 mm / s ? 720 mm / s,and the overlap ratio is 50%,the forming quality is the best,the relative density of the sample reaches the highest 99.3%,and the corresponding linear energy density is 0.26 J/ mm ? 0.36 J / mm.The experiments also showed that the quality of direct forming parts with high or low linear energy density is poor,and the porosity appears when the linear energy density is too high.(2)Studied the cracks morphology and mechanism of TC4 alloy sample formed by SLM,and the cracks suppression measures.Under the influence of residual stress,the cracks begin at the side edge of the workpiece,and begin at the edge notch,the unmleted powder adhesion.The Brittle phase was produced during the melting and re-cooling process of titanium alloy,which also leads to the crack initiation and propagation.The experimental results showed that the preheated substrate can effectively restrain the crack,when the laser power is 250 W,the scanning speed is 800 mm / s,the overlap ratio is 50%,the thickness of the layer is 80 um,the preheated substrate is 300?,the residual stress is reduced obviously,the crack suppression effect is very obvious.In summary,the optimum process parameters of Ti6Al4 V alloy formed by SLM are obtained,and the crack morphology and crack mechanism in SLM forming process are described.The research laid a foundation for the crack-free TC4 titanium alloy parts formed by SLM.