Chilled Rolls are cast iron based rolls alloyed with Nickel, Chromium and Molybdenum having a matrix of pearlite and carbide with flake graphite. The material has very good thermal properties coupled with property of imparting good surface finish to the product.
A chilled work roll in hot rolling is a roll that has been cooled to a low temperature during hot rolling process. This cooling process is essential as it helps to regulate the heat generated during the rolling operation and ultimately enhances the surface quality of the rolled product. By maintaining a lower temperature, the chilled work roll effectively minimizes the risk of overheating and ensures a more controlled and precise rolling process.
The use of chilled work rolls is particularly prevalent in industries such as steel production, where efficiency and product quality are of utmost importance. By incorporating chilled work rolls into the hot rolling process, It can significantly improve the production capabilities. The cooling of the work rolls not only enhances the overall efficiency of the rolling operation but also contributes to the production of high-quality steel products.
One of the key benefits of using chilled work rolls is the ability to achieve a superior surface finish on the rolled product. The cooling process helps to prevent surface defects and imperfections, resulting in a smoother and more refined surface. This is especially crucial in industries that require precise and flawless surfaces, such as automotive and aerospace manufacturing.
Furthermore, the controlled temperature of the chilled work rolls also plays a vital role in prolonging their lifespan. By keeping the rolls at a lower temperature.
A chilled roll features a surface layer of white iron produced by inducing rapid cooling at the surface (it means chill within the mould) which restricts the formation of free graphite. The core is of grey iron thanks to the slower rate of cooling and therefore the intermediate zone may be a mixture of white and gray iron. The necks and wobblers or spade ends aren’t to be chilled and hence retain greater toughness. The chilled layer is tough and wear resistant but it’s brittle.
It is suggested to use Chilled rolls in finishing stands only. Recommended sections – TMT BARS, FLAT BARS, ROUNDS BARS, SQUARE BARS.
There are two types of Chilled Rolls available.
1- Definite Chilled Rolls
| Hardness | C | Mn | Si | Cr | Ni | Mo | S | P |
| 60-70 | 3.00-3.30 | 0.60-0.90 | 1.10-150 | 0.80-1.20 | 1.50-1.80 | 0.25-0.35 | 0.06 max | 0.15 max |
| 70-75 | 3.10-3.40 | 0.60-0.90 | 0.70-1.10 | 1.20-1.60 | 2.50-4.00 | 0.25-0.40 | 0.05 max | 0.10 max |
2- Indefinite Chilled Rolls
Chemical Composition of Definite Chilled Rolls
| Hardness | C | Mn | Si | Cr | Ni | Mo | S | P |
| 50-60 | 3.00-3.20 | 0.60-0.90 | 1.10-1.50 | 0.80-1.20 | 1.50-1.80 | 0.25-0.35 | 0.06 max | 0.15 max |
| 60-70 | 3.00-3.30 | 0.60-0.90 | 1.10-1.50 | 0.80-1.20 | 1.50-1.80 | 0.25-0.35 | 0.06 max | 0.15 max |
