(1. 合肥工业大学材料科学与工程学院，合肥 230009；
2. 合肥工业大学机械工程学院，合肥 230009)
摘 要: 在600~800 ℃温度区间对TA15合金进行多向等温锻造，利用金相显微镜(OM)、透射电子显微镜(TEM)以及拉伸试验研究了变形温度对微观组织与力学性能的影响。结果表明：经3道次多向等温锻造后，TA15合金发生细化和球化，随变形温度的升高，等轴α机械破碎细化效应受到抑制，而片状α细化更加明显，不连续动态再结晶(dDRX)机制逐渐被激发。在800 ℃时，变形体内同时发生连续动态再结晶(cDRX)和dDRX，且在试样局部剧烈形变区域发生了形变诱导α→β相的转变。随变形温度的升高，材料抗拉强度和断后伸长率的变化趋势相反，且相比于伸长率，其抗拉强度下降更为显著，在600 ℃多向锻造条件下其抗拉强度最高。最后，通过经典强化模型的定量分析，证实了TA15合金多向等温锻造时其强度的提高除受细晶强化和位错强化外，晶粒形态、亚结构及大塑性变形(SPD)形成的特殊晶界结构也将对材料的屈服强度产生影响。
关键字: TA15合金；变形温度；大塑性变形；显微组织；力学性能
（1. School of Materials Science and Engineering, Hefei University of
Technology, Hefei 230009, China;
2. School of Mechanical Engineering, Hefei
University of Technology, Hefei 230009, China）
Abstract:The multi-directional isothermal forging (MDIF) experiments of TA15 alloy was carried out at 600-800 ℃. The effects of deformation temperature on microstructure and mechanical properties were studied by metallographic microscopy, transmission electron microscope and quasi-static tensile test. The results show that the grains of TA15 alloy are refined and spheroidized after three cycles of MDIF. With the increase of deformation temperature, the refinement effect of equiaxed α is restrained, while the refinement of lamellar α is more obvious. Additionally, the discontinuous dynamic recrystallization (dDRX) mechanism was gradually dominated. At 800 ℃, both continuous dynamic recrystallization (cDRX) and dDRX occur during deformation, and the deformation induced α→β phase transition occurs in the severely deformed region. The tensile strength and elongation of TA15 alloy show the opposite trend with the increase of deformation temperature, and the tensile strength decreases significantly compared with the elongation. Resultantly, the comprehensive mechanical properties of TA15 alloy are the best at 600 ℃. Through quantitative analysis, it is found that the increase of yield strength is affected not only by Hall-Petch strengthening and dislocation strengthening, but also by grain morphology, substructure and special grain boundary structure induced by SPD.
Key words: TA15 alloy; deformation temperature; severe plastic deformation; microstructures; mechanical properties
