Alloy Steel Cast Rolls

Alloy Cast Steel Rolls are obtained through a process of statically cast iron process. The rolls are classified as hypo-eutectoid steel rolls, which have been alloyed with Molybdenum and Chromium. The rolls are made to undergo heat treatment process involving double annealing. The process is followed tempering of the roll involving thermal shock resistance and toughness testing. The micro structure of Alloy Cast Steel Rolls is mainly pearlitic having broken cementite. The rolls are known for good weldability and offer high degree mechanical strength.

To improve the quality of the grey cast iron various alloying elements may be added to give the roll an increased hardness. These alloy iron rolls have only small quantities of nickel (Ni), chromium (Cr) and molybdenum (Mo) and they give slightly better wear and strength than the straight grey iron. The alloy iron roll with higher quantities of alloy additions is much harder and wears better though naturally it is more costly and must yield higher rolled tonnage. The presence of Ni promotes the formation of graphite but as it is in a very finely distributed form it leads to greater toughness and resistance to fire cracking. Cr increases the tendency to form combined carbon and restricts graphite formation so giving a much harder but more brittle iron. Mo and tungsten (W) promote the formation of combined carbon and in addition they add to high temperature strength. With a Cr alloy iron there is a tendency for collar breakage in section rolls due to the brittleness and in addition a good supply of water is necessary for cooling the rolls to avoid fire cracking