Study On Mechanical Properties Of TC4 Titanium Alloy By Laser Additive Connection Technology

Aiming at the traditional connection technology cannot connect the structure with large thickness,the laser additive connection technology is put forward to break through the limit of connection thickness and improve the precision of the connector.In this paper,the laser additive connection technology was used to study the microstructure and properties of the connectors,which provided a scientific basis for the laser additive connection technology.The main research contents of this paper are as follows:The TC4 titanium alloy was fabricated by laser additive manufacturing as the connecting substrate,and the laser additive connection technology was used to connect substrate.The influence of the sampling method on the mechanical properties and the difference in tensile strength and plasticity were studied.The stress of the grain boundary under different sampling methods is different which resulted in the performance is different.The strength of the connectors is similar to that of the substrate,but the plasticity is lower than that of the substrate.The maximum difference of the elongation is 3.8%,and the maximum difference of the shrinkage of the section is 12.45%.Choosing three groups of annealing temperature to optimize microstructure.It was found that as the annealing temperature was increased,the length,width and length-width ratio of?phase were decreased.The microhardness is proportional to the relative volume fraction of?phase.When annealing temperature is up to 920?,the relative volume fraction of?phase is least?0.45%?,and the microhardness value is lowest(474HV_0.2).The difference between laser and arc additive connection technology was analyzed and the effects of solution aging treatment on microstructure and properties were studied.The overall morphology of the laser connectors is consistent,and the columnar?crystals extend from the substrate to the top of the connection area.The morphology and size of?phase in the two areas are similar.However,the morphology of the wire connection area and the substrate area is greatly different,the connection area has coarse and equiaxial?grains,and the length-width ratio of the in-grain?phase is significantly greater than that of the substrate area.The comprehensive mechanical properties of laser additive connectors is better than wire connectors,and the strength and plasticity are higher than TC4 forging standard.The tensile strength of wire connector is similar to that of laser,but it's reduction of area is lower,the annealing state is about 14.9%lower than laser's,and the solution aging state is 13.4%lower than laser's.The solution aging treatment has obviously optimized the comprehensive properties of the connector.