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Plasma nitriding treatments are approved to reduce wear occurring in the field of hot forging applications. But there are demands for a further optimization of the processes in order to achieve adapted properties for differently loaded forging tools. This work presents the influence of main process parameters on the wear behavior of dies. The focused steel material of this work is DIN-X38CrMoV5-1 (1.2343), a standard hot forming tool steel. The influence of nitriding parameters like temperature, nitrogen flow and time on the nitriding depth, hardness and crack sensitivity has been investigated. Comparative application tests show the influence of different surface treatments on the wear behavior and lifetime of forging tools in an industrial environment

High mechanical, chemical and thermal cyclic loads characterize the load regime of hot forging applications. Additionally these loads are acting simultaneously which leads to a failure of the form giving tool components after a short tool life. Accounting for about 70% of all causes, wear is the main reason for production downtimes. Other failure factors are thermal and mechanical cracks as well as plastic deformation as a result of the loss of hardness due to the high thermal charge. The caused production downtimes can be reduced by surface modifications of the tools. Different results of recent research works prove the high potential of newly developed PVD and PECVD coating systems regarding the reduction of die wear. CrVN coating systems developed by PVD coating equipment and boron containing multilayered PECVD coating systems were applied to forging dies. Basic investigations of the occurring wear mechanisms show the qualification of the coating systems which have to be adapted to the decisive process related loads and damages

During forming operations the contact conditions relating to the surface of the tools, the intermediate coolant or lubricant and the hot work piece material are determining the material flow and the resulting wear. The possibilities for an optimization of the tool surfaces are aspects of various scientific activities of IST and IFUM and are subject of this paper. Tools typically made of hot working steel can be treated with different technologies in order to achieve wear resistant properties. First of all, the surface is mainly determined by its topography which is defined by the manufacturing method or applied finishing technology. This paper will give an overview to adjustable surface properties with additional conditioning methods like severe shot peening. The stabilization of the topography is a new approach to enhance the wear resistance of forming tools. Several models like the Abbott-Firestone graph are used in order to obtain suitable describing parameters such as the roughness-parameter sk. The development of skduring the running-in stage has a strong influence on the tool life which can be shown. A stabilization of the topographical conditions can enhance the service life of the tools. It will be shown, that this is possible by applying plasma diffusion treatments and thin film coatings by means of vacuum coating technologies.

The efficiency offorging processes is significantly influenced by the tool and scrap costs whichin their turn depend on the life time of forging dies. The tools used for hotforging are subject to process-related high mechanical, tribological, chemicaland thermal-cyclic loads which usually interact with each other. In comparisonto other manufacturing methods, the resulting load spectrum leads to extensivewear and thus to the failure of forging dies after a short tool life. Toincrease the wear resistance of forging dies, duplex treatments consisting ofplasma nitriding and plasma deposition techniques were used to improve thesurface properties and hence to increase the die life time. By basicinvestigation of the wear mechanisms the potentials of newly developed vanadiumdoped chromium nitride and boron containing titanium nitride coating systemswere investigated. Within the presented work it is demonstrated that vanadium-dopedchromium nitride layers have a high wear reduction potential for hot forgingdies.

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In the application field of forging, the form-giving tool components are subject to process-related severe environmental conditions, such as high mechanical loads acting simultaneously with high tribological and thermal charges. Due to high machine hour rates as well as increasing environmental requirements in terms of energy consumption, wear protection methods and suitable repair measures for forging tools become more and more important. Laser deposition welding represents an established process for the repair of complex shaped surfaces. A new approach is the addition of nano-sized ceramic particles to improve the mechanical properties. The main idea is to reduce the grain size of the cladded layers by adding nano-sized nuclei. A fine grained microstructure will improve strength as well as ductility and fatigue resistance. Furthermore small hard particles can improve the wear resistance without affecting the friction of the surface. After the cladding process the surface has to be finished usually by turning, milling and grinding operations. Within the presented paper the potential of nanoparticle-reinforced deposition welding with regard to increasing the wear resistance of forging dies will be examined. First, the process of nanoparticle-reinforced deposition welding will be presented. Afterwards it will be shown that yttrium oxide, titanium carbide and tungsten carbide nanoparticles in an AISI H10 matrix material will influence the friction coefficient between forging tool and material as well as the wear properties

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