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通过室温和高温拉伸性能测试,对比研究了Ti14合金经常规锻造(950℃)和半固态锻造(1000℃和1050℃)后试样在不同温度区间的宏观力学行为,分析了微观组织演变规律、断口微观形貌及断裂特征。结果表明:合金经半固态锻造后表现出高强度、低塑性的力学特征,随着半固态锻造温度的升高,合金力学性能下降。半固态锻造过程中组织的变化是引起力学性能差异的主要原因,而组织演变的主要特征是Ti2Cu析出相形态和分布的变化。随着半固态温度的升高,更多的液相在晶界析出,并在凝固过程中析出大量板条状Ti2Cu相,最终在晶界上形成偏析带组织。这种带状组织在拉伸过程中引发了解离断裂,导致了低塑性。此外,通过再结晶退火可以有效地细化半固态组织,改善强度性能。
The macroscopic mechanical behaviors of Ti14 alloy after conventional forging (950 ℃) and semi-solid forging (1000 ℃ and 1050 ℃) in different temperature range were studied by comparing tensile properties at room temperature and high temperature. The microstructure evolution was analyzed , Fracture morphology and fracture characteristics. The results show that the alloy exhibits mechanical properties of high strength and low plasticity after semi-solid forging. As the semi-solid forging temperature increases, the mechanical properties of the alloy decrease. The change of microstructure during semi-solid forging is the main reason for the difference of mechanical properties. The main feature of microstructure evolution is the change of morphology and distribution of Ti2Cu precipitates. With the increase of the semi-solid temperature, more liquid phase precipitates at the grain boundary and a large amount of lamellar Ti2Cu phase precipitates during the solidification process, finally forming segregation band structure on the grain boundary. This banded structure induces dissociation breaks during stretching, resulting in low ductility. In addition, the semi-solid structure can be effectively refined by recrystallization annealing to improve the strength properties.