热处理对TC4-DT钛合金组织性能的影响

Effect of Heat Treatment on Microstructure and Mechanical Properties of TC4-DT Alloy

研究了φ300 mm的TC4-DT钛合金几种热处理工艺参数对显微组织和室温性能的影响。研究表明α+β区锻造φ300 mm的棒材晶粒较大,低倍呈现模糊晶,局部区域有明显的清晰晶,表明大规格棒材锻造均匀性较差。大规格的棒材+双重退火热处理后,拉伸性能和断裂韧性均能达到Rm≥825MPa,RP0.2≥750MPa,A(纵向)≥8%,Z ≥15%;KIC(T-L)≥90 MPa.m12,具有良好的强度塑性匹配性能。α+β相区锻造的φ300 mm棒材经965℃/1h AC+550℃/6h AC和940℃/1h AC+570℃/6h AC处理后,疲劳裂纹扩展速率在ΔK=11MPa.m21时,分别达到2.833036×10-6mm/cycle和7.294209×10-6mm/cycle。

Effect of series heat treatment on microstructure and room temperature mechanical properties of TCA - DT alloy bar in diameter 300mm was investigated. The results show that in the microstructure of 300mm bar forged in α ＋ β region, the grains are coarse and vague with obvious grain bindery in some field, which suggests that the big TCA -DT bars has poor uniform inforgings. The tensile properties and fracture toughness of big bars being treated after α ＋ β double annealing can reach to Rm≥825 MPa,RP0.2 ≥ 750 MPa, A ≥ 8 %, Z≥15% ; KIC （ T - L） ≥ 90MPa · m1/2, indicating excellent match properties between strength and plasticity . The fatigue crack propagation vacuity can reach 2. 833036 ×10^-6mm/cyde and 7. 294209 ×10^-6mm / cycle respectively after heat treated at 965℃/lh AC ＋550℃/6h AC and 940℃/lh AC ＋570℃/6h AC heat treatments.