Indefinite chilled roll is a mill roll between chilled cast iron and gray cast iron with a carbon content of 2.5-3.5% and a silicon content of 0.7-1.6%. The structure of the roll body changes uniformly from the outside to the inside. The cold hard structure gradually transitions to the gray structure without significant change on the cold hard layer. The matrix structure of the working layer has uniformly distributed graphite. The content increases from the surface of the roll body to the depth with the decreased hardness. Therefore, there is no obvious boundary between the working layer of the roll body and the core. High NiCr indefinite chilled cast iron roll refers to the roll which contains alloy elements of high chromium, nickel, and molybdenum. The roll is manufactured by the centrifugal composite casting process. The existence of graphite in the base structure makes it has excellent thermal crack resistance and is widely used as a finishing roll for wide, medium and thick plate rolling mill and strip rolling mill.