材料期刊网

本文从热力学的活度概念出发,讨论了异种钢焊接接头的碳迁移现象。除接头两侧化学成分差别外,着重指出不同晶体结构对碳迁移有很大影响,强调了相变过程对碳迁移的重要作用。 根据一些异种钢接头碳迁移的特点,将碳迁移过程分为两类:第一类是在焊接高温极短时间内发生的,析出先共析铁素体是发生强烈碳迁移的主要条件;第二类是在相对低的温度长时间内发生的,铬等强烈形成碳化物元素的扩散速度是影响碳迁移过程的主要环节。 为抑制这两类碳迁移,从热力学和动力学两方面考虑,提出了具体措施。

Based on the concept of thermodynamical activity, carbon migration through the welding joint of dissimilar steels has been discussed. Apart from their difference in composition, their different crystal structures if exist may markedly influence the carbon migration and the effect of phase transformation must also be considered. The processes of the carbon migration may be classified as: 1. migration takes place quickly at high temperatures, the precipitation of preeutectold ferrite may given rise to violent migration; 2. migration takes place slowly at rather low temperatures, the diffusion rate of such elements as chromium which has a strong tendency to form carbide may be vital for carbon migration. Suggestion has been put forward on thermodynamic and kinetic considerations to retard carbon migration in either case cited above.