微合金钢焊缝组织中针状铁素体形核与长大驱动力

Driving force of acicular ferrite nucleation and growth in weld metal of microalloyed steel

摘要: 利用KRC模型对焊缝金属中针状铁素体转变的热力学驱动力进行了理论计算。计算结果表明,焊缝金属中AF(针状铁素体)相变开始温度的理论值为1100K(827℃)。试验所测得的焊缝金属中针状铁素体转变开始温度实际值为670℃,针状铁素体的相变热力学驱动力数值为ΔG^γ→AF+γ1≤-570J/mol。随着转变温度的降低和焊缝金属中碳含量的降低,针状铁素体的形核和长大驱动力增加。针状铁素体的总相变驱动力小于其形核和长大的驱动力,这种差距随转变温度的降低而增大。

Abstract: The thermodynamics driving force of aeicular ferrite(AF) transformation was calculated in theory using the model of KRC(Kaufman,Radcliffe,Cohen).The calculated result showed that the the oretical value of the starting temperature of AF transformation in weld metal was 1 100 K(827℃).And the actual value of the starting temperature of AF transformation in weld metal was 943 K(670℃).The thee retical value of the driving force of AF transformation in weld metal Was less than -570 J/m0l.The driving force of AF nucleation and growth increased with the decreasing of AF transformation temperature and the car-ben content in weld metal.The total driving force for AF trans formation was smaller than that of AF nucleation and growth.And the difference in-creased with the decreasing of AF transformation temperature.