PRETEX - A NEW METHOD OF PRODUCING TEXTUR ED SHEETS FOR THE HIGHEST REQUIREMENTS

Objective. The surface topography of steel sheet is an important quali ty-relevant product characteristic which decisively influences the tri bological forming behaviour as well as the adhesion and the optical pr operties of paint coatings. To be able, also in future, to reliably fu lfill the increasing demands placed on the surface topography in relat ion to complicated forming processes on high-speed transfer presses an d thin-layer paint coatings on large-area auto body parts, the Pretex( R) process has been developed to the stage of full industrial applicat ion. Summary. The newly developed Pretex(R) process has been in regula r use at Preussag Stahl AG since the beginning of 1997 for the product ion of non-coated and coated sheets. For this purpose the work rolls a re plated with Topocrom(R) in an enclosed reactor system that is unpar alleled worldwide and has been awarded a prize by the Fraunhofer Gesel lschaft. The surface topography of this extremely wear-resistant chrom ium multilayer system is characterised by a very uniform, stochastic d istribution of differingly large hemispheres which are transferred in the form of corresponding spherical indentations to the sheet during t he temper rolling process. The mean size and number of the topographic al features, and hence of the functional characteristics of the sheet, are reproducibly determined by the parameters of the roll plating pro cess. The numerous advantages of the Pretex(R) process make it possibl e, in contrast to the conventional texturing methods, to continue to f ulfill the highest demands reliably in future in terms of outstanding tribological forming behaviour and brilliant optical paint characteris tics.