Normalizing Rolling Process
Introduction
Normalizing rolling is a specialized process of hot rolling that bring steel sheets or plates to desired properties by normalizing different properties such as strength, bending performance and ductility. This process is carried out by exposing the steel to temperatures above the temperature of recrystallization, then allowing the steel to relax at a certain temperature. Consequently, normalizing rolling results in an austenite structure which is subsequently transformed into a ferrite/pearlite structure; depending on the steel grade and the process associated with cooling.
Types of Normalizing Rolling
Two types of normalizing rolling are commonly employed. The first is the conventional normalizing roll process in which a single hot-rolled coiled strip is passed through a series of rolls at a predetermined temperature and annealed at that temperature. The second is the cold normalizing roll process in which a strip is cold rolled and then heated to a predetermined temperature before performing a traditional normalizing roll.
Benefits of Normalizing Rolling
The primary benefit of normalizing rolling is increased strength and hardness of the steel. This increased strength allows for improved forming and welding performance in comparison with traditional hot rolling processes. Another benefit of normalizing rolling is improved ductility. As the steel crystal structure is refined during the process, the material is able to withstand more bending without cracking. This improved ductility is especially beneficial in steel applications that require bending or forming of complex shapes.
Process Overview
Normalizing rolling begins with selection of the starting material. The steel is then heated to a temperature near its recrystallization temperature and passed through a rolling mill. This process realigns the steel grains, refining the material’s strength, ductility and hardness. The steel is then cooled at a rate that reduces its hardness further, resulting in a ferrite/pearlite structure. Finally, any finishing treatments are applied to the steel for shipment to the customer.
Conclusion
Normalizing rolling is a specialized hot rolling process that produces steel with desired properties of strength, ductility and hardness. This process can be tailored to meet the specific requirements of the customer, allowing them to achieve the desired balance of performance and cost. By utilizing normalizing rolling, customers can reduce production costs while still achieving the desired mechanical properties of their product.
