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The presented study is focused on elaboration of the processing conditions of forging and controlled cooling for medium-carbon steel alloyed with micro additions, so as to meet the requirements of special civil engineering applications. Based on assumption of utilization of the heat attained in the forged part after hot deformation, austempering cycles were investigated so as to meet the microstructure-property combination required by special application. Laboratory tests of thermomechanical processing conditions were designed for different model heats of microalloy steel, were subject to semi-industrial verification in real process of forging. The laboratory investigation was based on the numerical analysis of evolution of strain and temperature in the forging process of the selected part, which provided data for theoretical prediction of the processing conditions. Wide range of microstructure-property combination achieved under different processing conditions, produced strength properties ranging from 620 to 1340 MPa and elongation-at-fracture up to 22 %. One of them, which was found the most proper for the application, was further used for definition of processing conditions of semi-industrial verification in the thermomechanical processing of a complex shape forged part. Thus, in addition to dependence of the material response on austempering conditions, transferability and reproducibility of laboratory tests' results into industrial conditions was studied.
Keywords: forging, thermomechanical processing, controlled cooling, martempering, grain refinement© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.