Influence of slide valve refractory composition on the quality of bearing steels teemed

Abstract

gree of compaction of the zone of the steel teeming hold of the part is obtained by pressing of plates with an insert corresponding to the projecting portion.The specific wear of the hole in the experimental corundum plates in service is 2~ times less than in the plates pressed by the normal method. 1. 2.3. 4.The replacement of ladle stopper assemblies by slide valves has made it necessary to organize the production of refractory parts satisfying the requirements for teeming primarily rimmed, semikilled, and low-alloy steels.As experience has shown, teeming of electric furnace steel, including constructional, through slide valves with the use of magnesite composition refractories is accompanied by contraction of the teeming channel, narrowing of the stream, a reduction in the rate of filling of the molds, and, as the result, a breakdown in the method of teeming and poorer ingot quality [i, 2]. With two usages of a set of magnesite refractories in the gate valve a tendency is observed toward an increase in the nonmetallic inclusion content in the steel [1].It is known [3, 4] that rational selection of refractories for slide valves with a certain structure and properties promotes normalization of the process of teeming a single heat of steel and elimination of contraction of the teeming channel and skull formation in it with sufficient life in service.

Experience in the use of chamotte nozzles in slide gates in teeming of stainless steel

“…Plant has conducted investigations [1][2][3][4] on the development and selection of refractory materials for slide valve parts in teeming of bearing and stainless steels, which are prone to clogging of the steel-teeming channel, for the purpose of providing stability in operation of the valve, a reduction in crust formation, and an increase in the times of use of the plates, nozzles, and well blocks.The service tests of mu!lite--corundum, mullite, and kaolin refractories showed that they answer these requirements since in use of them because of the reduced thermal conductivity in comparison with periclase parts there is a reduction in crust formation and clogging of the steel teeming channel and the teeming process is more regular without a reduction in steel quality [2,4].This article presents experience in the production of chamotte nozzles and nozzle collectors and service of them in the slide gates of steel-teeming ladles of stainless steel at the Dnepr Special Steel Plant.The parts of the experimental lot were produced at the Zaporozhe Refractory plant from the raw material used in the production of chamotte refractory parts, ShKGP chamotte, PLK-0 kaolin, and DN2 clay.The charge for the molding mixture consisted of granular chamotte with a water absorption of 3% containing about 39% A1203 and a mixture of ground kaolin and clay. The mixture, with a moisture content of about 6%, was prepared in mixing mills using the normal plant method for 4 min.…”

“…The service tests of mu!lite--corundum, mullite, and kaolin refractories showed that they answer these requirements since in use of them because of the reduced thermal conductivity in comparison with periclase parts there is a reduction in crust formation and clogging of the steel teeming channel and the teeming process is more regular without a reduction in steel quality [2,4].…”