固定自耗电极充填法熔铸复杂形状铸件的基础研究

Electroslag casting has become an important method of casting high quality castings rely on the advantage of the inherent quality of the castings, but so far the electroslag casting method of casting complex shape castings has still no breakthrough. Aganist electroslag casting process of casting complex shape castings using the method of compensating the filling ratio of fixed consumable electrode provided by the applicant, the priority research problems are as follows: (1) exploring the calculation method of complementing channel length; (2)revealing the intrinsic link among the complementary speed, the auxiliary structure of castings and technology and electroslag casting process parameters; (3) determining the correlation between electroslag casting parameters of the fixed and mobile consumable electrode; (4) establishing the relationship between the feeding capacity for casting hop with the molten metal melted by mobile consumable electrode and casting structure; (5)simulating the process of electroslag casting and researching on the method of real-time display; (d)defining the automatic control method of stabilizing the electroslag casting parameters of fixed consumable electrode. The research results will provide the theoretical basis for assisted structural design and process optimization of electroslag casting founding complex shape castings, and for determining the automatic control method of compensating fixed consumable electrode. The casting method through electroslag casting founding complex shape casting and the influence mechanism of related factors are explored in this project, which will promote the development of electroslag metallurgy technology. So the research has an important scientific significance and practical value.

电渣熔铸以精炼和凝固双优特长，成为高品质铸件的重要生产方法，但受铸件公共型腔的限制，到目前为止用电渣熔铸法铸造形状复杂铸件仍无突破性进展。本项目针对申请人首次提出的固定自耗电极充填法熔铸复杂铸件的铸造过程，重点研究：（1）补充通道长度的计算方法；（2）补充速度与铸件形状结构以及电渣熔铸工艺参数之间的内在联系；（3）固定自耗电极与移动自耗电极熔铸参数的相关性；（4）移动自耗电极熔化的金属液体对铸件顶部补缩能力与铸件结构的关系；（5）移动自耗电极和固定自耗电极双重熔化条件下金属熔池的温度场分布特点；（6）固定与移动自耗电极熔铸参数的自动控制方法。研究成果可为电渣熔铸形状复杂铸件工艺辅助结构设计和工艺优化、确定固定自耗电极充填法的自动控制方法提供理论依据；对于探索电渣熔铸复杂形状铸件铸造方法和相关因素的影响规律、推动电渣冶金技术的发展具有推动作用，所以项目的研究具有重要的科学意义与实际应用价值。

完成了固定自耗电极充填法熔铸复杂形状铸件的全部试验与研究内容，系统的研究了此方法的电渣熔铸过程，并建立了固定自耗电极充填法基础熔铸模型。取得了如下研究成果：（1）建立了固定自耗电极充填法熔化速率数学模型，得到了移动自耗电极、固定自耗电极平均熔化速率与铸锭凝固速率之间的关系式；得到了电极等效直径、电流密度与平均熔化速率之间的关系。（2）得到了铸件成型质量最佳的电极截面积参数匹配关系。（3）得到了柱状晶生长角度与自耗电极平均熔化速率的关系；金属熔池深度与自耗电极平均熔化速率的关系。（4）建立起相应的偏微分方程和恰当的边界条件，计算了熔铸初期固定自耗电极下端斜度不同的熔铸系统的温度场，并通过实验验证了温度场数值模拟的准确性。（5）计算了不同工艺参数下固定自耗电极充填法熔铸初期化渣过程熔渣水平长度、熔铸达到稳定阶段时的熔池间距。铸锭底部形状数值模拟结果与实验结果基本吻合。（6）对固定自耗电极充填法电渣熔铸稳定阶段的金属熔池形状进行了数值模拟,金属熔池形状模拟结果与实验结果基本吻合。结合电渣熔铸渣沟形成原理，模拟了电渣熔铸过程中渣沟形成过程，得到了避免渣沟形成的最佳工艺参数。（7）对固定自耗电极充填法两电极间金属熔体填充通道进行了数值模拟，得到了电流密度、电极间距以及电极等效直径对熔铸过程的影响规律，得到了保证铸件表面质量的最佳工艺参数。本项目提出的固定自耗电极充填法从根本上解决了复杂形状铸件的无公共型腔问题，对电渣熔铸的发展具有积极的推动作用，具有较高的学术价值和应用价值。