材料韧脆转移过程的数学模拟和定量分析

研究了Cr24Al2Si铁素体不锈钢韧脆转移过程的性能-温度曲线的数学模拟，找到了其最佳的韧脆转移数学模型。它可以通过在韧脆转移温度范围内、温度间隔不小于30K的二个试验点（最好是三个试验点）数据代入求得。通过韧脆转移的数学模型，还可以找到换算系数。上述关系，不仅可以成为确定韧脆转移温度通用准则，提供一种定量分析的数学方法，而且使韧脆转移曲线转化为韧脆机制转移曲线，从而为建立冷脆断裂机制图奠定了基础。

THE MATHEMATICAL SIMULATION AND THE QUANTITATIVE ANALYSIS OF DUCTILE-BRITLE TRANSITION PROCESS FOR MATERILS

This paper studies the mathematical simulation of the properties-temperature curve of ductile-brittle transition process for materials and finds the best mathematical model of ductile-brittle transition. That is T=Tc-1/b ln(Ymax-Ymin/Y-Ymin-1) where Y----the test value; T----test temperature ; To----the transition temperature; Ymax----the upper shelf value of the curve; Ymin----the under shelf value of the curve, 1/b---a constant relating to temperature range of transition. If 1/b is unknown, it should be found by two points. Their temperature interval should not less than 30K(Three points will be better) 1/b=T2-T1/ln(Y′2-Y′1Y′2/Y′1-Y′1Y′2) Y′=Y1/Ymax Y′2=Y2/Ymax where T1 and T2 are test temperatures, Y1 and Y2---the test values at T1 and T2 respectively. According to the mathematical model mentioned above, the following conversion is found. Tc=TNDT+3.48 1/b where Tc and TNDT are the energy ductile---brittle transition temperature and ail-ductile transition temperature respectively. These relationships obtained above, not only find the common principle for determining the material’s ductile-brittle transition temperature and the mathematical method of a quantitative analysis for ductile-brittle transition’s process, but also find the method to translate the properties transition curves into the mechanism transition ones, and the basis to build the mechanism diagram of cold-brittle fracture.