2种退火方式对牙科铸造纯钛力学性能的影响

Effect of two kinds of annealing methods on the mechanical properties of dental titanium castings

目的:观察不同的退火方式对牙科纯钛铸造后力学性能的影响。方法:在非真空和真空2种退火方式下,对牙用纯钛铸件的抗拉强度、屈服强度和延伸率3种力学指标进行测试;采用金相显微镜和扫描电镜观察铸件的显微组织结构及断口形貌。结果:当非真空退火温度为700～800℃时铸件的抗拉强度、屈服强度和延伸率均有所提高,真空退火温度为750～850℃时,铸件的抗拉强度、屈服强度均有所提高;700℃非真空处理组的力学拉伸性能、金相结构及断口形貌均为最佳,即力学性能最优良。结论:通过热处理可以提高牙科铸造纯钛的力学性能,真空退火后铸件的力学性能提高值低于非真空退火。

Objective： To investigate the influence of different annealing methods on the mechanical properties of dental titanium castings.Methods： The titanium castings were treated by non-vacuum method and vacuum method,respectively.The ultimate tensile strength（σ b）,0.2% offset yield point strength（σ 0.2）,and elongation to fracture（δ） were surveyed by a universal testing machine with 15 mm pre-marked gauge interval.The appearances of incision of the broken samples were investigated with scanning electron microscope.The center microstructures of the unbroken samples were determined by metallurgical microscope.Results： The ultimate tensile strength（σ b）,0.2% offset yield point strength（σ 0.2）,and elongation to fracture（δ） of the samples all increased at the annealing temperature of 650,700,750 ℃.At the vacuum annealing temperature of 650,750 and 850 ℃,both of the ultimate tensile strength（σ b） and 0.2% offset yield point strength（σ 0.2） increased.When the annealing temperature was 700 ℃ and the holding time was 1 h,dental titanium castings had the best tensile properties,appearances of incision and center microstructures in all groups.Conclusion： The mechanical properties of dental titanium castings can be enhanced by heat treatment.The enhancement of tensile properties by vacuum annealing is lower than those by non-vacuum annealing.