Ti-B25钛合金热变形行为及加工图
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摘要
在Gleeble 3800型热力学模拟实验机上对Ti-B25钛合金进行高温热压缩实验,得到温度为800～1 000℃,应变速率为0.01～10 s~(-1)条件下的真应力-真应变数据。通过计算应变速率敏感指数m值、能量耗散率η值以及失稳系数ξ值,绘制不同真应变条件下的加工图,从而识别出对应真应变下的稳定变形参数区和失稳区,并获得Ti-B25钛合金在实验范围内的安全变形参数区间为温度900～1 000℃,应变速率0.01～0.2 s~(-1)。此外,通过微观组织分析发现,Ti-B25钛合金在低温高应变速率下呈现出的失稳方式是晶粒破碎以及明显的流变失稳现象,在低温低应变率下其两相组织中发生α相球化;在中温高应变速率呈现出的失稳方式是中部大变形区不均匀的局部塑性变形,在中温低应变率下则主要发生了动态再结晶现象。
Thermal compression experiments were conducted on Ti-B25 alloy with Gleeble 3800 thermodynamic simulator.The true stress-true strain data were obtained under the conditions of 800～1 000 ℃ and strain rate of 0.01～10 s~(-1).By calculating the strain rate sensitive index m,energy dissipation rate η and instability coefficient ξ,the processing maps under different true strain conditions were drawn,and the stable deformation parameters and instability regions corresponding to the true strain were identified.The safe deformation parameters of Ti-B25 titanium alloy in the experimental range were obtained as follows:temperature 900～1 000 ℃,strain rate 0.01～0.2 s~(-1).In addition,the microstructural analysis shows that the instability modes of Ti-B25 titanium alloy at low temperature and high strain rate are grain breakage and obvious rheological instability.The α phase spheroidization occurs in its two-phase structure at low temperature and low strain rate.While the instability modes at medium temperature and high strain rate are local plastic deformation in the middle large deformation zone,and the dynamic recrystallization occurs mainly at the medium temperature and low strain rates.
Thermal compression experiments were conducted on Ti-B25 alloy with Gleeble 3800 thermodynamic simulator.The true stress-true strain data were obtained under the conditions of 800～1 000 ℃ and strain rate of 0.01～10 s~(-1).By calculating the strain rate sensitive index m,energy dissipation rate η and instability coefficient ξ,the processing maps under different true strain conditions were drawn,and the stable deformation parameters and instability regions corresponding to the true strain were identified.The safe deformation parameters of Ti-B25 titanium alloy in the experimental range were obtained as follows:temperature 900～1 000 ℃,strain rate 0.01～0.2 s~(-1).In addition,the microstructural analysis shows that the instability modes of Ti-B25 titanium alloy at low temperature and high strain rate are grain breakage and obvious rheological instability.The α phase spheroidization occurs in its two-phase structure at low temperature and low strain rate.While the instability modes at medium temperature and high strain rate are local plastic deformation in the middle large deformation zone,and the dynamic recrystallization occurs mainly at the medium temperature and low strain rates.
引文
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[3] BARNETT M R.Influence of deformation conditions and texture on the high temperature flow stress of magnesium AZ31[J].Journal of Light Metals,2001,1(3):167-177.
[4] LIU J,CUI Z,LI C.Modelling of flow stress characterizing dynamic recrystallization for magnesium alloy AZ31B[J].Computational Materials Science,2008,41(3):375-382.
[5] AL-SAMMAN T,GOTTSTEIN G.Dynamic recrystallization during high temperature deformation of magnesium[J].Material Science and Engineering A,2008,490(1):411-420.
[6] PRASAD Y V R K,RAO K P.Processing maps and rate controlling mechanisms of hot deformation of electrolytic tough pitch copper in the temperature range 300-950 ℃[J].Materials Science & Engineering A,2005,391(1):141-150.
[7] SIVAKESAVAM O,PRASAD Y.Hot deformation behavior of as-cast Mg-2Zn-1Mn alloy in compression:a study with processing map[J].Materials Science and Engineering A,2003,362(2):118-124.
[8] PRASAD Y.Processing maps:A status report[J].Journal of Engineering and Performance,2003,12(6):638-645.
[9] 黄光胜,汪凌云,陈华,等.2618铝合金的热变形和加工图[J].中国有色金属学报,2005,15(5):763-767.
[10] 黄树海,赵祖德,夏志新,等.AZ80合金高温变形行为及加工图[J].稀有金属材料工程,2010,39(5):848-852.
[11] GANESAN G,RAGHUKANDAN K,KARTHIKEYAN R.Development of processing map for 6061 Al/15% SiCp through neural networks[J].Journal of Materials Processing Technology,2005,166(3):423-429.
[12] TAN C W,XU S N,WANG L,et al.Effect of temperature on mechanical bahaviour of AZ31 magnesium alloy[J].Transactions of Nonferrous Metals Society of China,2007,17(1):41-45.
[13] KIM H Y,KWAON H C,LEE H W,et al.Processing map approach for suiface defect prediction in the hot bar rolling [J].Journal of Materials Processing Technology,2008,205(1):70-80.
[14] ZIEGLER H.Progress in solid mechanics[M].New York:Wiley Press,1963:58-69.
[15] 曾卫东,周义刚.加工图理论进展[J].稀有金属材料与工程,2006,5(35):673-677.
[16] 董显娟,鲁世强,王克鲁.Ti-6Al-2Zr-1Mo-1V合金塑性流动失稳预测[J].稀有金属材料与工程,2010,39(9):49-53.