A new ductile iron for mechanically and thermally strained rolls Part 2: material development varying Ni, Mo, Cr content using DoE

ABSTRACT

For manufacturing of steel wires, tubes and profiles in hot rolling mills, the toughest conditions occur in the front rolling stands where the mechanical load comes along with a constant change of hot rolling stock and cooling liquid. Conventional roll materials as pearlitic or acicular cast irons are not able to overcome these intense conditions because of their lack of ductility. A fine selection of alloying elements leads to a new material with a microstructure uniting bainite, austenite and martensite inducing high hardness and strength, without lacking elongation. For this purpose, a full-factorial design of experiments was created consisting of three alloying elements in two concentrations each. The alloys were cast, heat-treated and underwent extensive investigations on mechanical properties and microstructure. The results were analysed and implemented in mathematical models whose combination and optimisation led to the identification of the ideal alloy meeting the required strength, hardness and elongation.

KEYWORDS:

• Ductile iron
• rolling application
• alloy design
• design of experiments
• process simulation
• microstructure

Acknowledgements

The authors thank the Federal Ministry for Economic Affairs and Energy for their support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Federal Ministry for Economic Affairs and Energy [ZF4105814US7, ZF4506901US7, ZF4507001US7].