Research on the Surface Quality of ESR Large Slab Ingots

Abstract

A special bifilar 40t electroslag remelting(ESR) furnace for slab products has been fabricated to produce heavy plates for special application. The ESR slabs with the maximum thickness of the world in size of 980 mm thickness, 2000 mm wideness and 2800 mm length have been produced successfully. However, the ingots surface quality is a serious problemn in ESR process for large slab ingots, for ingot and mold with a relatively mobile, larger ingot contraction and thicker slag skin. Using CaF2-CaO-Al2O3-SiO2-MgO slag, suited remelting rate, lower filling ration, smooth movement of mold and adjusting taper of the mold and are necessary for improving surface quality of the ESR large slab ingots.

Numerical Investigation on Solidification Behavior of Slab Ingot during Electroslag Remelting Process

“…However, the quality control in the ESR process for large-sized slab ingots presents distinct challenges compared with conventional ESR, primarily due to the nonuniformity of the temperature field and cooling conditions. The comparatively large width-to-thickness ratio of ESR slab ingots and the wide distance between the ingot corners and the central area of the heat source make it difficult to control the surface quality [2].…”

Effect of B2O3 on the Crystallization Behavior of CaF2-Based Slag for Electroslag Remelting 9CrMoCoB Steel

“…It is an effective countermeasure to inhibit the loss of B by adding B 2 O 3 into the molten slag by decreasing the degree of slag-metal reactions [6,7]. However, the surface quality of the ingot is another important focus during ESR production, and the surface quality of the ESR ingot is related to the molten slag [8]; generally, it is a consequence of inappropriate lubrication and horizontal heat transfer in mold through the slag film, besides the melting rate and electrode immersion depth [9,10]. Horizontal heat transfer of the slag is strongly dependent on the crystallization characteristics of the slag [11,12].…”

Effect of TiO2 on the crystallisation behaviour of CaF2–CaO–Al2O3–MgO slag for electroslag remelting of Ti-containing tool steel

“…Although this countermeasure is effective in inhibiting the loss of titanium, unreliable drawing-ingot-type operation and/or poor surface quality of as-cast ESR ingot is difficult to be avoided generally. [3][4][5] This is generally a consequence of inappropriate lubrication and horizontal heat transfer in mould through slag film, besides melting rate and electrode immersion depth. 6,7 It is necessary to study the crystallisation behaviour of ESR-type TiO 2bearing slag in order to provide adequate lubrication and control appropriate horizontal heat transfer across slag film in mould during refining process.…”