Engang Wang

Abstract:

Ni-based corrosion resistant alloy is widely used in the oil industry and nuclear energy due to its good performances on high temperature resistant and corrosion resistant. However, the Ni-based corrosion resistant alloy is generally fabricated by casting ingots, which has some disadvantages of high energy consuming, severe quality defects, low production efficient, etc. The continuous casting technique to produce Ni-based corrosion resistant alloy has become the front technique, which increases the production rate and reduces the product cost. In this paper, a new continuous casting process of Ni-based corrosion resistant alloy is developed with compound electromagnetic fields. One of the electromagnetic field is set on the mould near the melt surface to improve the surface quality of billets such as depth oscillation marks and surface cracks. The another electromagnetic field is set on the secondary cooling zone to improve the internal quality of billets such as large grain size, the severe segregation of element, centerline shrinkage and internal cracks. The aim of research is to develop a sustainable industrial processing for the fabrication of Ni-based corrosion resistant alloy. In this paper, the Incoloy800H alloy billet was successfully fabricated in pilot continuous casting machine with compound electromagnetic fields (EMCC). With the effect of high frequency electromagnetic field, not only the oscillation marks but also the depression and the cracks on the billet surface were disappeared, the surface quality of Ni-based alloy billets was significantly improved. The oscillation mark depth decreased from 0.75 mm (without electromagnetic field) to 0.18 mm (with electromagnetic field). Meanwhile, with the effect of lower frequency electromagnetic stirring (EMS), the equiaxed grain ratio of billet increase to 41.45%, the grain size and dendrite segregation of element was reduced. The internal quality of Ni-based alloy billets was also significantly improved. The distribution of TiN inclusions in the billet was also discussed with the compound EMCC process.