When selecting, the main requirements for rough rolls are strength and thermal crack resistance; the working rolls of small 20-high rolling mills weigh only about 100 grams, while the weight of backup rolls of wide and heavy plate rolling mills has exceeded 200 tons. Therefore, when selecting rolls, the main material for safe bearing (various grades of cast iron, cast steel or forged steel, etc.) must first be selected according to the basic strength requirements of the rolling mill for the rolls.
• Hardness
However, the speed of the finishing roll is high, and the final rolling product must have a certain surface quality. The main requirements for it are hardness and wear resistance. Then consider the wear resistance that the roll should have when it is used. Since the wear mechanism of the roll is very complex, including mechanical stress, thermal action during rolling, cooling, chemical action of the lubricating medium and other actions, there is no unified index for comprehensive evaluation of the wear resistance of the roll. Since the hardness is easy to measure and can reflect the wear resistance under certain conditions, the radial hardness curve is generally used to approximate the wear resistance of the roll.
• Shock proof
In addition, there are some special requirements for the rolls. For example, when the reduction is large, the rolls are required to have strong biting ability and impact resistance.
• Finish
When rolling thin-gauge products, the rigidity, uniformity of structure and properties, processing accuracy and surface finish of the rolls are strictly required.
• Cutting performance
The machining performance of the working layer of the roll body should be considered when rolling the complex section steel.
When selecting rolls, some performance requirements of the rolls are often opposed to each other, and the purchase and maintenance costs of the rolls are very expensive. Therefore, the technical and economic advantages and disadvantages should be fully weighed to decide whether to use cast or forged, alloy or non-alloy. Yes, single material or composite material.
