Papers by Keyword: Tool Steels

Abstract: Tools applied in various cutting processes are constantly exposed not only to thermal, mechanical but also chemical stresses, which has a significant impact on the wear of the cutting tool, but also on the cutting performance itself. By measuring the components of the cutting force, we can predict the wear or suitability of the cutting tool for machining given types of materials. The present study investigates the effect of changing the shape of the tool geometry on the magnitude of cutting forces in turning tool steels. The measurement of cutting forces was carried out on a conventional lathe with a Dynamometer attachment, interchangeable cutting inserts of DNMG and WNMG type were used as tools, tool steels produced by PM and conventional metallurgy were used as the machined material. The cutting tools were selected regarding their common use in engineering production, the tool steels were selected with regard to their application in industry in the production of rotary tools.

Abstract: Thanks to innovative processing routes, even conventional materials which have been around for years can be manipulated to obtain unconventional microstructures with specific mechanical and physical properties. This also holds for various semi-solid forming processes, which represent a dynamically developing field. Yet, these processes are still under development due to their technological complexity. One of the innovative methods of semi-solid processing is mini-thixoforming. As it focuses on very small-size products, it offers very steep heating curves and extremely high solidification and cooling rates, unlike conventional thixoforming. These features have profound impact on the evolution of microstructure and the resulting properties of the product. As in the conventional thixoforming process, complex-shaped products can be manufactured with high precision, using a single forming step. The potential and capabilities of the process were explored using the ledeburitic X210Cr12 steel as the experimental material. Once the optimum conditions were found, other tool steels were used for trials as well. Thanks to closely-controlled temperature field, mini-thixoforming was successfully used on a steel with a freezing range of a mere 15 °C. The microstructure evolution in the mini-thixoforming process is an issue of its own. The final microstructure of X210Cr12 after processing consisted of more than 90 % of austenite and chromium carbides. Semi-solid processing of a steel with a high vanadium content led to a microstructure comprising MA matrix and globular vanadium carbides. In a low-alloyed steel, martensitic microstructure was obtained.Keywords: thixoforming, mini-thixoforming, semi-solid processing, tool steels

Abstract: This paper discusses the issues of modelling and smart computer support for low-pressure nitriding aimed at achieving more effectively the compatibility between the actual post-treatment properties of a material and the designed properties, which will contribute to improved repeatability of the processes. The principal objective of the experiment was to acquire better understanding of the cause and effect relationship of the low-pressure nitriding processes and to develop the methodology of designing functional and effective processes of low-pressure thermochemical treatment, using effective computational methods. The paper proposes a method of steel classification based on its chemical composition and a model used to forecast the properties of material after low-pressure nitriding, based on the artificial neural networks.

Abstract: The aim of this contribution is to test the suitability of selected types of tool steels used for manufacturing of injection molds. Experiments were realized by the simulation of adhesive wear using laboratory equipment Amsler, which allows the testing of grinding pairs. Evaluated grinding pairs consisted of tool steel and two types of roundels. Tested polymeric materials were based on pure PA6 and PBT filled with short glass fibers, prepared by mixing process in twin screw extruder. The wear of five types of tool steels were evaluated by weight decrease before and after the experiment, while changing the friction coefficient of grinding pairs, material of grinding pairs and sensing the roughness of steel before and after wear.

Abstract: Developing steady state models to conduct and control repeatable processes of low-pressure nitriding is not possible in practice as the nitrogen content in a nitrided layer depends not only on the nitriding parameters, but also on the content of alloying elements in steel and the nucleation stage which is difficult to control. Therefore, a new concept of conducting such processes has been proposed. It has been shown that application of an appropriate method of activation of steel parts surface makes the nucleation stage uniform and reduces its duration. A system based on artificial intelligence methods has also been proposed, which enables modelling and control of non-equilibrium processes of low-pressure nitriding of tool steels. This model is based on the “boost-diffusion” schedule of the process.