TC18合金β相区等温锻造显微组织和力学性能

Microstructure and Mechanical Properties of β Isothermal Forged TC18 Alloy

摘要:

研究了β相区等温变形温度、变形程度对TC18钛合金显微组织和力学性能的影响，讨论了工艺、组织和性能之间的关系。结果表明，TC18合金显微组织对等温锻造温度的变化比较敏感，两相区等温锻造和单相区等温锻造的显微组织分别为双态组织和网篮组织；与两相区锻造相比，β相区锻造获得了更高的强度和断裂韧性，但塑性有所降低，且随着变形温度的升高，强度和塑性均呈现下降趋势，断裂韧性稍有升高。β相区变形量较小时，组织遗传性导致合金保留了部分魏氏组织形貌，塑性较低，断裂韧性较高；当变形量达到60%时，晶粒破碎程度大，次生片状α相发生一定程度球化并弥散分布，组织变得均匀细小，合金强度和塑性保持良好的匹配，断裂韧性较高，综合性能最好

Abstract:

The effects of deformation temperature and deformation degree on the microstructure and mechanical properties of TC18 titanium alloy during the β isothermal forging were studied. Results show that the microstructure of TC18 titanium alloy is sensitive to the variation of isothermal forging temperature. Deforming in (α+β)-phase gets a typical bi-modal microstructure while deforming in β-phase gets a net-shaped microstructure. When deforming above the β-transus temperature, the forging shows higher strength, fracture toughness and lower plasticity. With higher deformation temperature, both the strength and the plasticity decrease while the fracture toughness increases a little. Deforming above the β-transus temperature, typical Widmanstatten, coarse β grains, and the highest fracture toughness are obtained in small deformation degree. When the deformation degree reaches 60%, grains crack seriously, secondary lamellar α further globalize and disperse, and the microstructure becomes even fine, so the alloy’s strength and plasticity maintain good matching, fracture toughness is better and the best comprehensive properties are achieved