Studying possibilities to improve the functional properties of metallurgical rolls

The paper presents results of investigations and authors’ opinion on improving functional properties of metallurgical rolls cast from G200CrMoNi 4-3-3 cast steel, one of most often used for rolls in section mills. These mills feature quicker than flat rolls wear of tool’s pass, what requires more frequent regeneration. The machining requires a relatively low hardness, which is ensured by the pearlitic matrix of cast steel studied. The authors suggest to achieve the optimisation of tribological properties through adjustment of the chemical composition or/and modification of the heat treatment. In the study presented only the carbon content was slightly inereased (having carbide-forming elements in view) resulting in the increase in ledeburitie carbides. However, this most obvious way of improving the abrasive wear resistance increases the threat of rolls cracking and therefore requires verification using the fracture mechanics method. Statistical analysis of randomly selected few dozens of rolls have shown for this grade of cast steel a trend to reduce the carbon content by the manufacturer, maintaining it at the lower range of limits specified by the standard and not to increase it. The analysis of the wear mechanism of surfaces of worn out rolls made of G200CrMoNi 4-3-3 cast steel allows making suggestions on the possibilities of heat treatment changes, what also has been presented in the paper.