LAUSR

The possibility of modelling the quenching process brings an advantage in predicting the phase transformations in steel and its related microstructure, hardness and grain size. Mechanical analysis allows the prediction of deformations occurring during the quenching. In this manner, it is also possible to find out the values of stress generated in the material during quenching. The above method enables us to predict, in advance, whether a given material is suitable for the proposed type of heat treatment, whether it meets the specified parameters and whether it will be economically viable to process the given material to its required properties and purpose. Thus, the simulation serves the purpose of choosing the suitable parameters of quenching; however, it may also address the treatment of the component in view of its desired properties after quenching and elimination of crack formation during the quenching. Numerous previous studies have laid the foundation for simulation of the phase transformations in steels. Initially, those studies dealt with the two-dimensional simulation. In particular, the studies published by authors [1-3] focused on modelling the phase transformations in steels, namely the two-dimensional modelling of austenite-pearlite eutectoid steels. The aforementioned studies did not include the diffusionless transformation that is significant for quenching. Over time, studies on modelling extended to the threedimensional modelling and post-quenching deformation modelling. Recent studies of quenching modelling, such as those by teams of authors [4, 5, or extensive studies by [6-8] have already dealt with modelling the diffusionless transformations in steel. However, those are related to conventional carbon steels whose structure prior to quenching consists of homogeneous austenite and after quenching it contains diffusionless transformation products such as martensite, bainite and residual, i.e. untransformed austenite. The above methodology focuses on the issue of modelling the quenching of hyper-eutectoid steels that are not formed of homogeneous austenite in the austenitising temperature domain. During the heat treatment process, their structure features complex globular carbides of iron and alloying elements. Those are dissolved during the austenitising, depending on austenitising temperature and austenitising temperature holding time, thus increasing the proportion of carbon in austenite. With increasing the carbon content in austenite the hardness achieved after quenching increases as well, [9, 10]. Although the software designed to model steels contains a database of such steels' material properties, in the actual modelling, however, they are based on the assumption that these steels, similar to conventional carbon steels, are formed of homogenous austenite prior to the immersion in the quenching medium. This issue is the most pronounced in the form of a comparison between the modelled Vickers hardness and the actually achieved hardness.