EVALUATING DIFFERENT ROUTES OF PREPARATIO N FOR CUTTING TOOLS MADE OFHIGH-SPEED STEEL

Derived from its significance and the range of application covered by high speed steels for cutting tools and dies, research work is done pe rmanently for improving their efficiency. Besides measures for the eva luation of the chemical composition the optimization of technology is included for economising. In this connection investigations were accom plished, comprising the application of high ! cooling rates at the sol idification of the liquid alloy with subsequent powder metallurgical t reatment for the production of deformable billets to obtain an improve d quality. Despite of its wide spread application for cutting tools an d dies super alloyed high speed steel is still covered by investigatio ns in certain an amount, for improving the efficiency of the productio n of billets and bars and the materials properties. From knowledge of the phase transition liquid/solid with subsequent primary and secondar y reactions, emphasis was put on controlling the conditions of solidif ication during the last decade. In the frame of an experimentally supp orted study, tests with gas- as water atomized powders, ESR (electro s lag remolten) billets and short fibres from the alloy specification AS P23 as the initial melt were performed, comparatively. The accelerated heat transfer during solidification results in a homogeneous microstr ucture which is basis for the improved materials properties. Rapidly s olidified and subsequently crashed short fibres exhibited higher quali ty. Manufacturing of the water atomized powders compared with that gas atomized failed, because of their oxygen content to high. An optimiza tion of the melt extraction process for the short fibres and some addi tional cutting tests are proposed, finally.