论文部分内容阅读
研究了镍基高温合金Ni-10Cr-15Co-6W-6Mo-4Al-2Ti真空电弧重熔过程中自耗电极熔化特征及电极端部不同区域内Mg的分布。发现在电极侧表面存在着一个重熔金属环,Mg在其中分布相当均匀,而在重熔金属液层及液固两相区内Mg分布则不均匀。金属液层厚度随其在电极端部所处位置而异,其平均值为1—1.5mm。分析结果指出,Mg含量从金属液层/气相界面经液固两相区至原始电极区即随距金属液层/气相界面距离δ_1增加而增加。重熔金属环中Mg含量[Mg]_r及熔化金属液外层(δ_1<0.40mm)中Mg含量均低于重熔锭中Mg含量[Mg]_i。在试验条件下,如自耗电极Mg含量以[Mg]_e代表,则[Mg]_(0.15)=0.18[Mg]_e=[Mg]_r;[Mg]_(0.40)=0.30[Mg]_e=[Mg]_i。真空电弧重熔过程中,Mg挥发主要发生于电极端部熔滴形成阶段,流经电极端面的金属液不能全部暴露于真空下,Mg挥发过程受控于Mg原子由原始电极区向金属液层/气相界面迁移的速度。传质系数K_(12)=0.107cm·s~(-1)。重熔锭中Mg含量[Mg]_i=[Mg]_e exp(-K_(12)·A·γ·W~(-1))。显然,可通过控制电极Mg含量[Mg]_e及熔化速率W来实现最佳Mg控制。
The melting characteristics of consumable electrode and the distribution of Mg in different regions at the tip of Ni-10Cr-15Co-6W-6Mo-4Al-2Ti alloy were studied. It is found that there is a remelting metal ring on the electrode side surface. Mg distributes quite evenly among them, while the distribution of Mg in the remelted metal liquid layer and liquid-solid two-phase region is not uniform. The thickness of the metallic liquid layer varies with its location at the end of the electrode, with an average value of 1-1.5 mm. The results show that the content of Mg increases from the liquid metal / gas phase through the liquid-solid two-phase region to the original electrode region, ie, the distance δ_1 from the metal liquid layer / gas phase increases. The Mg content in the remelted metal ring [Mg] _r and the Mg content in the outer layer of the molten metal (δ_1 <0.40mm) are both lower than the Mg content [Mg] _i in the remelted ingot. Under the experimental conditions, if the consumable electrode Mg content is represented by [Mg] _e, [Mg] _ (0.15) = 0.18 [Mg] _e = [Mg] _r; [Mg] _ (0.40) = 0.30 [Mg ] _e = [Mg] _i. In the process of vacuum arc remelting, Mg volatilization mainly occurs in the droplet forming stage at the end of the electrode. The liquid metal flowing through the end face of the electrode can not be fully exposed to vacuum. The Mg volatilization process is controlled by the Mg atoms from the original electrode region to the metal liquid layer / Vapor phase interface migration speed. Mass transfer coefficient K_ (12) = 0.107cm · s ~ (-1). The content of Mg in the remelted ingot [Mg] _i = [Mg] _e exp (-K_ (12) · A · γ · W -1). Obviously, optimal Mg control can be achieved by controlling the electrode Mg content [Mg] _e and the melting rate W.