Research on the ingot shrinkage in the electroslag remelting withdrawal process for 9Cr3Mo roller

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Abstract In order to reduce the air gap between ingot and mould in the electroslag remelting withdrawal (ESRW) process, the taper of the mould should be consistent with the ingot shrinkage.Athree-dimensional mathematical model was developed to describe the interaction of multiple-physical fields (Joule heat, electromagnetic field, velocity field, and temperature field) and ingot shrinkage during the ESRW process. The variations of material thermal and mechanical properties, as well as the yield function with temperature, were considered. The shrinkage behavior of 9Cr3Mo roller in the ESRW process was simulated using the sequential coupling method. A good agreement between the calculated value and the measured valuewas obtained in the temperature field and stress field. Numerical results showed that maximum values of current density, Joule heat, and electromagnetic forcewere at the electrode corner of the slag bath. The direction of the magnetic flux density was tangential to the slag bath and had a clockwise rotation. There were two pairs of vortices and two high temperature zones in the slag bath. The shrinkage displacement was obtained through thermal-stress analysis. As the distance from the mould outlet decreases, the shrinkage displacement of ingot increases. As for the electroslag remelting withdrawal process for 9Cr3Mo roller, the variation of the shrinkage displacement from the slag/metal interface to the mould outlet was 0.0028 m. The maximum shrinkage displacement is at the mould outlet, and the value was 0.0089 m.