Development Of Electroslag Continuous Casting Technology And Its Process Research

Products by the electroslag remelting (ESR) process have the advantages of high purity, compact structure, homogeneous composition and clean surface, etc., so electroslag remelting technology has been developed quickly in recent years. In the standard ESR operation, it has been an established practice to adjust the meltrate such that the ratio between kg/h remelted and ingot diameter in mm does not, or only very little exceed a value of 1.0, so ESR has a shortcomings of low production efficiency. With the batch production, the productivity of the electroslag remelting process is lower and the cost is higher, specially, when remleting the ingot of diameter less than 300mm. In modern metallurgical production process, continuous casting (CC) access to the rapid development with high efficiency. Therefore, we combine with the advantages of ESR and CC to develop an electroslag continuous casting (ESCC) technology, and make the research on the process technology and quality control.The ESCC equipment developed in this work mainly consists of bifilar mode, T-shaped mould, metal level detecting system and drawing device, etc. Through theoretical analysis and experiments, we obtain a conclusion that influencing factors of ESCC bellits'surface quality are voltage and current, slags, drawing velocity, the ratio of electrode diameter and mould's surface conditions, and influencing factors of ESCC bellits'inner quality are slags, the relationship between melting rate and solidification.On characteristics of ESCC basis, we identify requirements on slags, and calculate slags' physical parameters. By simulation on temperature field of the slag bath and metal pool, we have made reasonable process parameters including voltage and current, molten steel location, cooling system, etc.We have done tests under conditions that were 60 volts voltage,3800 amps current, R2 slag, and the W9Mo3Cr4V steel. The testing and analysis of the products were done, which included the surface quality, macroscopic examination, microstructure and inclusions analysis. The inner structure of billets is compact and homogeneous and no remarkable inclusions, segregation and cracks. The distribution of inclusions is uniform and the size of them is tiny with the diameter of 5 to 6μm, which is similar to that in the standard electroslag remelting ingot. Through comparison, we found that the distribution and the size carbide structure in remelted billet is better than that in standard ESR ingot at the same melt rate. In the following process, carbide structure in remelted billet is easy to be broken into pieces.By comparison of a large number of experimental results, we found that not only ESCC still maintain characteristics of ESR, but also carbide uniformity and size of W9Mo3Cr4V ESCC bellits is super to ESR ingots with the same melting rate. Thses experiments prove that ESCC is feasible.Finally, this paper introduced the process of technology from laboratory to the industrialization. From the results of the macrostructure and inclusions of remelted products, we can see that ESCC is a mature technology for industrial applications.ESCC is an innovative technology, combining the advantages of ESR and CC, indeed realized the purpose of reduce costs and improve efficiency. ESCC fill a gap of the domestic electroslag metallurgical technology.