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The influence of microstructure on the mechanical properties of metallurgical rolls made of G200CrMoNi4-3-3 cast steel

Brodziak A., Stradomski Z., Pirek A.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 3

21-24

EN

The subject of the study is the high-carbon tool cast steel G200CrMoNi4-3-3 used for metallurgical rolls, especially in section rolling mills. The test material was derived from a roll damaged in production; therefore, the authors had the material in a raw state at their disposal, on which they were able to carry out additional heat treatment operations. The pearlitic matrix of casting steel G200CrMoNi4-3-3 allows machining to be done to modify the pass or to remove any defects, and the primary and secondary precipitates of carbides enhance the tribological properties. The authors have been for years involved in the optimization of the structure of this material by slight correction to its chemical composition and/or the modification of heat treatment. The presented principles of heat treatment modifications will lead to considerable economic and ecologic profits. It has also been demonstrated that raising slightly the contents of carbide-forming elements, which markedly increases the quantity of transformed ledeburite, results in an enhancement of tribological properties. The analysis of a dozen or so rolls exploited down to the dead roll diameter has shown that roll of cast steel with increased contents of carbon and carbide-forming elements exhibit better service properties, as characterized by the amount of feedstock rolled. Such a method of enhancing the service properties required the assessment of fracture toughness, which was verified using the linear-elastic methods of fracture mechanics.

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Studying possibilities to improve the functional properties of metallurgical rolls

Stradomski Z., Pirek A., Stachura S.

Archives of Foundry Engineering

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2008

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Vol. 8, iss. 1 spec.

313--316

EN

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.

3

Kształtowanie mikrostruktury i własności staliw nadeutektoidalnych

Krawczyk J., Rożniata E.

Hutnik, Wiadomości Hutnicze

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2006

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Vol. 73, nr 4

170-177

PL

W pracy przedstawiono sposoby kształtowania mikrostruktury i własności staliw nadeutektoidalnych. Zaproponowane technologie obórbki cieplnej są możliwe do zastosowania w aktualnych warunkach technologicznych polskich odlewni.

EN

This work presents the methods of forming the microstructure as well as designing the properties of hypereutectoid steels. Proposed heat treatments are specially attractive for use in Polish foundries, because they directly conform to their technological requirements.