| Addictive manufacturing(AM)of titanium alloys has shown the significant advantages in fabricating complex constructions.It mainly includes the synchronous powder feeding forming technology presented by laser deposition manufacturing(LDM)and the powder bed forming technology by selective laser melting(SLM).In order to realize the high precision and rapid prototyping of large complex stru cture components,in this paper,the hybrid forming Ti6Al4 V alloy with double structu re was prepared by combined LDM process and SLM process.However,the special p rocess of laser addictive manufacturing results in anisotropy,high strength and low pla sticity,the heat-treatment is an important way to adjust phase composition,microstruct ure and improve mechanical properties.Exploring more perfect heat-treatment technolo gy can bring LDM-SLM hybrid manufacturing technology into fully capacity.Firstly,the anisotropy of microstructure and properties of LDM-SLM hybrid manufacturing samples were studied.Phase composition,microstructure and mechanical properties of four different hybrid components were studied by OM,SEM and XRD.The results showed that: the hybrid components of four hybrid methods have obvious anisotropy.Secondly,the influence of high temperature annealing temperature on microstructure and mechanical properties of LDM-SLM hybrid forming components was studied.The hybrid components were annealed at 750℃×2h,AC,800℃×2h,AC and 850℃×2h,AC,respectively.It was found that: with the increase of annealing temperature,the plastic increased obviously,despite the strength of hybrid components decreased slightly.When the annealing temperature at 850 ℃,the tensile specimen shows double-necked phenomenon due to machining hardening,and the comprehensive performance was optimized.Finally,the effect of different times of cyclic thermal treatment on microstructure and hardness of LDM-SLM hybrid manufacturing samples was investigated.Heat-treatment system with 960℃/10min?750℃/10 min as a complete cyclic thermal treatment,the cyclic index was 2 times,4 times,6 times and 8 times,respectively.XRD and EBSD methods were used to analyze the microstructure evolution.The result shows that: with the increase of cyclic index,the plastic was improved significant.After 6 cycles of thermal treatment,the microstructure and mechanical properties of LDM zone,SLM zone and HAZ were homogenized. |
