材料期刊网

研究了直径为410mm的A-286合金自耗电极真空电弧重熔过程的熔化特征及电极端部不同区域内Mn的分布,发现Mn挥发主要发生于电极端部熔滴形成阶段。Mn含量在金属液层内部分布均匀,接近于挥发反应的平衡值;在液固两相区内,从金属液层内表面至电极原始区Mn含量呈直线增加。可以认为,Mn挥发过程受控于Mn原子在液固两相区内的迁移速度。重熔锭中Mn含量[Mn]_l=[Mn]_eexp(-K_1·nA_d·γ·W~(-1))+[Mn]_f[1-exp(-K_l·nA_d·γ·W~(-1))],显然,可通过控制电极Mn含量[Mn]_e及熔化速率W来控制[Mn]_l。此外,对粘附于结晶器壁的挥发凝聚层进行了成分分析,发现凝聚层由Mn,Cr,Fe,Ni组成,Mn含量大于40％,而挥发物质Cr,Fe及Ni在合金重熔前后的重量百分浓度基本不变。

The remelted characteristics of a 410 mm diameter consumable electrode and the Mn distribution in various regions at the electrode tip during VAR process of alloy A-286 in a 506 mm diameter water cooled crucible were studied. It was found that the Mn evaporized mainly in the forming period of droplets at the electrode tip. The Mn distributed rather homogeneously in the liquid metal film. As the remelted rate of electrodes was quite small at the end of VAR process, the Mn content of the liquid metal film seemed to be nearly that under the equilibrium conditions for the Mn evaporation reaction. The Mn content increased linearly from the liquid metal film/liquid-solid two phase region interface to the original electrode. It was suggested that the Mn evaporation is controlled by the migration rate of Mn atoms in the two phase region. The Mn content of remelted ingot, [Mn]_i, can be calculated in terms of the following equation: [Mn]_i=[Mn]_e exp (-K_1n_dγW(-1))+[Mn]_f {1-exp(-K_1n_dγ W(-1))} Obviously, [Mn]_i can be controlled by controlling the Mn content of consumable electrode, [Mn]_e, or the remelted rate, W. In addition, the composition of the condensate layer on the crucible wall has been analysed. The results indicated that the condensate layer consisted of the evaporation species Mn, Cr, Fe and Ni and it contained more than 40% of Mn. The. Mn and.Cr contents in the condensate layer were higher than those in the remelted ingot and the Fe and Ni contents in the condensate layer lower, but the Cr, Fe and Ni contents in the remelted ingots were the same as those in the consumable electrodes.