微合金钢焊缝针状铁素体相变热力学研究
Research on Transformation Thermodynamic of Acicular Ferrite in Weld Metal of Micro-alloyed Steel
刘 艳1,2， 吴毅雄1， 雷 毅2， 金 鑫1
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作者单位：（1.上海交通大学 上海激光制造与材料改性重点实验室，上海 200240； 2.中国石油大学 机电工程学院，山东东营 257061）
中文关键字：针状铁素体； 超组元； 贫碳区； 切变； 驱动力
英文关键字： acicular ferrite; super-element model; carbon-depleted region; shear; driving force
中文摘要：基于预相变形成奥氏体贫碳区的特点，采用KRC、LFG、MD活度模型和超组元算法，建立了Fe-C-X系微合金焊缝针状铁素体在奥氏体贫碳区切变转变的相变热力学模型，并针对某种微合金钢成分进行了数值计算。结果表明，三种模型具有相同的变化规律，即针状铁素体相变驱动力随着奥氏体贫碳区碳含量的降低而增加，随着相变温度的降低而增加。因此，基于贫碳区的相变模型可获得比以往模型更大的相变驱动力，从热力学角度来讲，针状铁素体在奥氏体贫碳区很可能具有切变转变的相变过程。
英文摘要：According to the characteristic of carbon-depleted regions which is formed during incubation period, thermodynamic models of the transition of acicular ferrite welding in the carbon-depleted region was established by using the active model of KRC, LFG, MD, and the super-element algorithm. The calculation of numerical value was carried for certain micro-alloy steel. The results show that the same laws are gained from the three models. It means that the state changing drive force of acicular ferrite increases with the decrease of carbon content in the carbon-depleted regions and recedes with drop of temperature. Therefore, the model of state changing grounding on the carbon-depleted regions can obtain, greater drive force of state changing in comparison with previous model. From the point of view of thermodynamics, the acicular ferrite in carbon-depleted regions is likely to have the state changing process of shearing transition.