ZHANG Xi-liang
,
ZHOU Chang-yu
钢铁研究学报(英文版)
The constant embrittlement curve for constant segregation concentration on grain boundary of impurity element P and relationship between equilibrium grain boundary segregation concentration and operation time for 225Cr-1Mo steel were derived based on the theory of equilibrium grain boundary segregation. The mechanism of step-cooling test and mechanism of de-embrittlement for 225Cr-1Mo steel were explained. The segregation rate will increase but equilibrium grain boundary segregation concentration of impurity element P will decrease as temperature increases in the range of temper embrittlement temperature. There is one critical temperature of embrittlement corresponding to each embrittlement degree. When the further heat treating temperature is higher than critical temperature, the heat treating will become a de-embrittlement process; otherwise, it will be an embrittlement process. The critical temperature of embrittlement will shift to the direction of low temperature as further embrittlement. As a result, some stages of step-cooling test would change into a de-embrittlement process. The grain boundary desegregation function of impurity element P was deduced based on the theory of element diffusion, and the theoretical calculation and experimental results show that the further embrittlement or de-embrittlement mechanism can be interpreted qualitatively and quantitatively by combining the theory of equilibrium grain boundary segregation with constant embrittlement curve.
关键词:
step-cooling test
,
critical embrittlement temperature
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embrittlement mechanism
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grain boundary desegregation
彭宁琦
,
唐广波
,
刘正东
,
吴秀月
金属学报
doi:10.3321/j.issn:0412-1961.2009.03.013
根据Aaronson提出的超组元模型,借助Ae3的实验数据,提出了修正的置换型元素Xi(Xi=Si,Mn,Ni,Co,Mo,Al,Cu,Cr)的Zener两参数,修正中考虑了合金元素间的交互作用.修正后的超组元模型的预测精度明显改善:Ae3计算值与实验值的标准差为10.8℃,与Thermo-Calc计算值的标准差为2.35℃;Ae1计算值与实验值的标准差为6.8℃.按照马氏体相变热力学的计算方法,采用经修正的参数计算了马氏体相变开始温度Ms,提高了Ms点的预测精度,计算值与实验值的标准差为25.3℃.
关键词:
相变
,
热力学
,
超组元模型
,
相变平衡温度
盛广
,
杨志刚
金属学报
根据Fe--C--Xi合金系的正平衡和准平衡热力学模型，推导了简便的奥氏体--铁素体相变驱动力计算解析式。根据公式, 代入合金原始成分和Ae3温度, 即可准确计算正平衡和准平衡模式下的奥氏体--铁素体相变驱动力。采用这一方法计算了Fe--C--Mn--Si--Ni--Cr--Mo--Cu八元系的正平衡和准平衡奥氏体--铁素体相变驱动力。
关键词:
正平衡
,
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