The coating of continuous casting molds made of Ag- or CrZr-alloyed copper, preferably with nickel, is state of the art today (Fig. 1). In addition to qualitative improvements in the surface of continuous casting slabs, the main benefit here is an increase in the durability of the molds and thus a reduction in costs. However, this was not always the case. In the mid-1970s, EVERTZ was the first in the world to successfully electroplate copper ingot mold plates for a single-strand circular arc slab line at a steel mill in the eastern Ruhr region of Germany. This application resulted in a serious improvement in the surface finish of the continuous cast slabs. The cracks which had appeared in some grades, so-called star cracks, had disappeared. Their elimination prior to use in the heavy plate mill had previously required considerable scarfing. Soon it also became apparent that the durability of the ingot mold plates had increased significantly. The manufacturers of copper mold plates had massively opposed the new coating technology, fearing the loss of their supply shares. But as always, the better is the enemy of the good; and so the galvanic nickel plating of copper mold plates began an exemplary worldwide triumphal procession. Following this success, in the early 1980s EVERTZ developed a one-piece continuous casting mold made of electrodeposited layers, preferably for billet plants (Fig. 2). Either the entire mold is made of copper or the inner layer is made of nickel, e.g. to reduce damage when the cold strand is run in and thus increase durability. European Patent 0 125 509 was filed on April 13, 1984, published on November 21, 1984 and granted on September 9, 1987. This is only one of more than 30 registered patents dealing with continuous casting technology, mainly ingot molds. Today, in addition to the first plant in Langenfeld, EVERTZ operates a second one at its American subsidiary EVERTZ Technology Service in Middletown, Ohio. And this one reports a new highlight. After intermediate machining in the mechanical workshop of the Copper Division of ETS, equipped with 3 CNC milling machines with up to 10 axes from the EVERTZ subsidiary KLOPP, an ingot mold fully coated with nickel in the electroplating shop of ETS achieved the record durability of 544 melts when used in the thin slab plant of the Flat Roll Division of Steel Dynamics, Inc. in Butler, Indiana. Ingot mold plates have traditionally been mechanically reworked several times during their journey to remove cracks developed during a campaign during casting on milling machines. In the process, copper is worked off and the plate becomes thinner. This can be done several times until a critical residual thickness is reached between the casting surface and the water slots or cooling water holes. Then the plate must be scrapped. Several years ago, EVERTZ further developed the previously described technology of electroplated layers for a one-piece pipe mold for the electroplating of copper on copper base plates of slab molds. This makes it possible to compensate for the reduction in the original plate thickness caused by machining. This leads to a significant increase in the service life of the plate with the associated considerable reduction in costs. The plate need not be scrapped until much later, if at all. Thus, in principle, the infinite mold is born. This newly developed copper-on-copper coating technology for slab mold plates has already been successfully applied in German and American continuous casting plants. Fig. 3 shows a bending specimen of an electroplated Cu layer including a nickel coating as the basis for the perpetual mold.

"stahl und eisen" 07/2013