MODELING OF DYNAMIC MATERIAL BEHAVIOR IN HOT DEFORMATION - FORGING OF TI-6242
MODELING OF DYNAMIC MATERIAL BEHAVIOR IN HOT DEFORMATION - FORGING OF TI-6242
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DOI：
10.1007/bf02664902
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发表时间：
1984-01-01
期刊：
影响因子：
--
通讯作者：
BARKER, DR
中科院分区：
文献类型：
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作者：
PRASAD, YVRK;GEGEL, HL;BARKER, DR
提出了一种新的材料行为建模方法，该方法考虑了热变形过程中发生的动态冶金过程。该方法将工件视为整个加工系统中的功率耗散器，并从应变速率（ε）与流动应力（σ）之间的本构方程中计算耗散功率cocontentJ = ε oσε <$dσ。最佳的温度和应变速率条件是对应于J的最大值或峰值的温度和应变速率条件。结果表明，J与材料的应变速率敏感性（m）有关，当m =1时，J达到最大值（Jmax）。通过冶金过程的功率耗散（J/Jmax）的效率被证明是材料的动态行为的一个指标，是有用的，在获得一个独特的组合的温度和应变速率的处理，也在划定的内部断裂的区域。在这种建模方法中，不需要原子机制的优先知识或评估，并且该方法即使在多于一个耗散过程发生时也是有效的，这在具有复杂微观结构的商业合金的热处理中是特别有利的。该方法已应用于Ti-6242热锻过程的模拟。研究了α+ β和β预成形坯的组织行为，结果表明，在927 °C（1200 K）和1CT·3s·1的应变速率下获得了这两种预成形坯的最佳热锻工艺条件。耗散效率随温度和应变速率的变化与材料中发生的动态微观结构变化相关。
A new method of modeling material behavior which accounts for the dynamic metallurgical processes occurring during hot deformation is presented. The approach in this method is to consider the workpiece as a dissipator of power in the total processing system and to evaluate the dissipated power co-contentJ= ∫oσε ⋅dσ from the constitutive equation relating the strain rate (ε) to the flow stress (σ). The optimum processing conditions of temperature and strain rate are those corresponding to the maximum or peak inJ.It is shown thatJis related to the strain-rate sensitivity (m) of the material and reaches a maximum value(Jmax) whenm =1. The efficiency of the power dissipation(J/Jmax) through metallurgical processes is shown to be an index of the dynamic behavior of the material and is useful in obtaining a unique combination of temperature and strain rate for processing and also in delineating the regions of internal fracture. In this method of modeling, noa prioriknowledge or evaluation of the atomistic mechanisms is required, and the method is effective even when more than one dissipation process occurs, which is particularly advantageous in the hot processing of commercial alloys having complex microstructures. This method has been applied to modeling of the behavior of Ti-6242 during hot forging. The behavior of α+ βandβpreform microstructures has been exam-ined, and the results show that the optimum condition for hot forging of these preforms is obtained at 927 °C (1200 K) and a strain rate of 1CT•3s•1. Variations in the efficiency of dissipation with temperature and strain rate are correlated with the dynamic microstructural changes occurring in the material.