TY - THES

T1 - Investigation of the Expected Advantages with Respect to the Electroslag Current Conductive Mold Technology

AU - Kubin, Michael

N1 - embargoed until 12-11-2015

PY - 2010

Y1 - 2010

N2 - The present master thesis in collaboration with INTECO special melting technologies GmbH and the special steel plant Breitenfeld deals with the possibilities of the new developed Electroslag - Current Conductive Mold Technology (ES-CCM). Due to the inherent limitations of the standard electroslag remelting process with respect to segregation phenomena, it is not possible to manufacture large diameter ingots, especially segregation prone alloys, at any high melting rate. However, a lower melting rate leads to a poor surface formation, due to the decreased power input into the slag bath and hence the adjusted low slag temperature. In order to overcome this strict relationship between meltrate and slag temperature, INTECO special melting technologies GmbH developed therefore the ES-CCM Technology to control melt rate and slag temperature independently from each other. With an additional power input in the boundary area of the slag bath using a current conductive element, a sufficient slag temperature even at lower melting rates could be achieved in order to get a good surface formation. By means of remelting test ingots in a 750mm diameter current conductive mold and a 750mm diameter conventional mold, the pool profile formation and morphology were investigated. In addition, the homogeneity of the test ingots were determined with a optical emission spectrometry with pulse discrimination analysis. The results of the present research study show that remelting at low melting rates using a current conductive element leads to a shallow liquid metal pool in combination with a good surface appearance. Furthermore, the test results regarding the homogeneity indicate that no macrosegregations are present in any of the remelted test ingots and that the element distributions are uniform over the entire cross-section. Hence, these experimental results in conjunction with the experiences gained through the trial plant operations constitute a step forward in the development of this new remelting technology.

AB - The present master thesis in collaboration with INTECO special melting technologies GmbH and the special steel plant Breitenfeld deals with the possibilities of the new developed Electroslag - Current Conductive Mold Technology (ES-CCM). Due to the inherent limitations of the standard electroslag remelting process with respect to segregation phenomena, it is not possible to manufacture large diameter ingots, especially segregation prone alloys, at any high melting rate. However, a lower melting rate leads to a poor surface formation, due to the decreased power input into the slag bath and hence the adjusted low slag temperature. In order to overcome this strict relationship between meltrate and slag temperature, INTECO special melting technologies GmbH developed therefore the ES-CCM Technology to control melt rate and slag temperature independently from each other. With an additional power input in the boundary area of the slag bath using a current conductive element, a sufficient slag temperature even at lower melting rates could be achieved in order to get a good surface formation. By means of remelting test ingots in a 750mm diameter current conductive mold and a 750mm diameter conventional mold, the pool profile formation and morphology were investigated. In addition, the homogeneity of the test ingots were determined with a optical emission spectrometry with pulse discrimination analysis. The results of the present research study show that remelting at low melting rates using a current conductive element leads to a shallow liquid metal pool in combination with a good surface appearance. Furthermore, the test results regarding the homogeneity indicate that no macrosegregations are present in any of the remelted test ingots and that the element distributions are uniform over the entire cross-section. Hence, these experimental results in conjunction with the experiences gained through the trial plant operations constitute a step forward in the development of this new remelting technology.

KW - Elektroschlackeumschmelzen

KW - CCM-Technologie

KW - 12% Chromstahl

KW - Innenqualität

KW - Oberflächenqualität

KW - electroslag remelting

KW - current conductive mold

KW - 12% chromium steel

KW - internal quality

KW - surface quality

M3 - Master's Thesis

ER -