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Upgrading of ledeburitic type powder metallurgy (p/m) tool steels.

The aim of the project is to prolong the life-time of p/m
ledeburitic steel tools by upgrading the tool material and
applying various surfacing techniques.

The use of P/M made ledeburitic tool steels becomes of even greater importance because of their excellent combination of microstructure and mechanical properties. These materials are mostly used in heat treated condition and have hardness ranging usually between 700 and 800 HV. Introduction of the tools processed by such a way into application increased the life-time several times, depending on the replaced material, nature of worked material, etc. The service time of tools may furthermore be prolonged by the application of several PVD - coating methods onto the tool surface. The loading of tools, however, may cause in many cases the damage of thin and brittle PVD surface overlay. This is due to marked differences in physical properties between PVD - overlay and substrate. Therefore it is desirable to modify the substrate properties before PVD - coating, at least in thin near surface region. Convenient technique for the substrate modification has to fulfil the following criteria: 1) It must be performed at lower temperature than the temperature of the last heat treatment cycle; 2) The technique should permit the achievement of sufficiently thick inter-layer with high hardness; 3) The properties of inter-layer should be well controllable by the adjustment of processing parameters. One of very convenient technique which fulfils the above listed requirements is plasma nitriding. It has been determined that even the plasma nitriding, without any subsequent PVD coating, improves the wear resistance of the M2-grade ledeburitic steel considerable. The TiN PVD-made layer induces additional wear resistance improvement which makes more than thousand percents. Nevertheless, there exists large potential for optimization of plasma nitriding with respect to the surface hardness, microhardness depth profiles, etc., in order to achieve an optimal surface and interface (nitrided layer - PVD overlay) properties. Another suitable technique how to increase the service time of cold work tools is the mechanical alloying of rapidly solidified powder by some hard particles with subsequent consolidation of such prepared powder mixture. This way is expected to be investigated whereas some low alloy RS powder like M2-grade will be used for experimental and practical testing. Several coating methods were developed recently for the cold work applications but the problems with the substrate - overlay adhesion always occur in some cases. This means that the first goal of practical experiments (tool testing) within the new project should be focused to the investigation of reproducibility of this technique. Nevertheless, new either simple or multiplex coating will be developed. It is well known that the PVD coatings differ one from each others by physical properties. This fact permits to vary the surface properties of tools by the alterations of the sequence of which the layers are deposited on the substrate. It has been recently shown that SHS composite targets and electrodes are well suitable for deposition of multi-component thin and thick coatings using PVD, Electrospark Alloying (ESA) and Thermo-Reactive Surface Strengthening (TRESS). One of the most important advantages of ESA and TRESS methods is possibility to deposit thick films, up to 0.5 mm with a very high adhesion between hard coating and substrate. Moreover no problem with adhesion is in case of ESA and TRESS techniques because these methods are the similar of microwelding. Upgrading the P/M ledeburitic steel like M2 using ESA, TRESS and magnetron sputtering using SHS-electrodes makes it possible to achieve a significant improvement in wear resistance, e.g. stamps, medical tools, punches, rollers, pressforms, dies. New composite electrodes and targets in systems Ti-B-Al, Ti-Si-N, Ti-B-N, Ti-Si, Ti-Si-Zr-O, Ti-Cr-B, Cr-B will be synthesized and used in research and development. Keywords: P/M ledeburitic steel, heat treatment, coating.
Acronym: 
UPLETOOLS
Project ID: 
2 728
Start date: 
01-01-2002
Project Duration: 
36months
Project costs: 
800 000.00€
Technological Area: 
Coatings
Market Area: 

Raising the productivity and competitiveness of European businesses through technology. Boosting national economies on the international market, and strengthening the basis for sustainable prosperity and employment.