真空退火处理对选区激光熔化TA2纯钛显微组织及力学性能的影响

采用选区激光熔化工艺制备了医用TA2纯钛试样,利用光学显微镜、扫描电镜、万能材料试验机和维氏硬度计等分析手段对比分析了真空退火处理对试样显微组织和力学性能的影响,还利用氮氢氧联合测定仪研究了试样中含氧量的变化。结果表明,合适的真空热处理工艺能明显改变纯钛零件显微组织,从马氏体组织向近等轴组织转变;能有效改变制备零件的力学性能,使拉伸强度及屈服强度降低,塑性升高;除此之外,真空热处理还能降低制备零件的含氧量和硬度。经800 ℃真空退火保温1 h后,试样的显微组织为近等轴组织,其各项力学性能均满足GB/T 13810—2017《外科植入物用钛及钛合金加工材》要求,其抗拉强度为670.3 MPa,屈服强度为609 MPa,断后伸长率为20.3% ,断面收缩率为44.7% 。

Effect of vacuum annealing on microstructure and mechanical properties of selective laser melted TA2 pure titanium

The medical TA2 pure titanium specimens were prepared by the selective laser melting process. Effect of vacuum annealing on microstructure and mechanical properties of the specimens was been compared and analyzed by means of optical microscope (OM), scanning electron microscope (SEM), universal material experiment machine and Vickers hardness tester. The change of oxygen content in the specimens were also studied by means of combined determination apparatus for oxygen, nitrogen and hydrogen. The results show that appropriate vacuum heat treatment process can obviously change the microstructure of specimens from martensite structure to near-equiaxial structure, and effectively change the mechanical properties of the specimens, reduce the tensile strength and yield strength, and increase the plasticity. In addition, vacuum heat treatment could reduce the oxygen content and hardness. When annealed in vacuum at 800 ℃ for 1 h, the microstructure of specimens is the near-equiaxial structure,and the mechanical properties are satisfied with the requirement of the GB/T 13810—2017 Wrought titanium and titanium alloy for surgical implants,and the R_m, R_p0.2, A and Z are 670.3 MPa, 609 MPa, 20% and 44.7%, respectively.