Forged Roll Heat Treatment

Forged Roll Heat Treatment

Heat treatment is the key differentiator in UES rolls.

Work Rolls

We have developed a unique, full coil static induction heat treatment process that enables us to maximize work and intermediate roll performance by optimizing the critical attributes:

  • Microstructure
  • Depth of Hardness
  • Residual Stress

UES has developed unique proven heat treatment technology utilizing the Full Coil Static Induction hardening process.  This is contrasted with progressive induction as seen in the following diagram.

Hardening

In Full Coil Static Induction, the entire roll body is heated to the austenitizing temperature.  As a result, the working layer of the roll body can be austenitized at lower temperatures and longer times than progressive induction.   The result is a microstructure with improved wear resistance due to less dissolved carbides as shown below:

Graph

Chromium Analysis

In addition, the static induction process creates a more favorable residual stress distribution due to the more gradual temperature profile used during the hardening process.

Classic Hardening Process

The final result in heat treating a roll using this method is achieving maximum roll performance due to the roll having the following superior attributes:

  • The higher percent volume carbides in the matrix improves the roll’s wearability characteristics and retains its finish for longer campaign runs.
  • Is superior to resisting roll marks and indentations.
  • Due to the lower residual stress levels near the roll’s surface, our rolls are less susceptible to catastrophic spalling and rapid propagation of surface cracks to the interior. This permits removal of cracks during normal roll maintenance.

Back-up Rolls

We utilize two heat treatment methods for back-up rolls in order to provide the proper microstructure (martensitic/bainitic matrix) for our customer’s given mill application. The preferred heat treatment method is based on the hardness specification, specific roll performance history, and the criteria for changing rolls.