Sendzimir and Cluster Forged Rolls

Sendzimir and Cluster Mills have operating conditions significantly different from conventional Cold Strip Mills (CSM). They use small-diameter work rolls supported by multiple intermediate and backing elements, which generate very high specific pressure in the strip contact zone. For this reason, these mills are used for stainless steels, silicon steels, and other hard-to-roll materials.

Under such conditions, conventional forged roll materials such as Cr-Mo or Cr-Ni-Mo grades cannot provide sufficient wear resistance, surface stability, and load-bearing support. Therefore, higher-alloy materials are selected according to actual rolling conditions, rolled product surface requirements, contact pressure, and the required balance between wear resistance and toughness.

Roll naming varies with mill layout. In 20-High Sendzimir Mills, the roll stack is generally described by work rolls, first intermediate rolls, second intermediate rolls, and backing bearings (backing assemblies). In some layouts, driven and idler positions appear within the intermediate-roll set. In Z-High Mills and other Cluster Mills, work rolls are supported by intermediate rolls together with side-support or backing rolls. Each roll type has a different function in the roll system:

Sendzimir 20-High mill roll nomenclature diagram showing work rolls, first intermediate rolls, second intermediate rolls, and backup bearings assemblies in a color-coded roll arrangement.

The material groups described here are used mainly for work and intermediate rolls. Backup rolls, side-support rolls, and backing assemblies are typically based on Cr-Mo or Cr-Ni-Mo forged grades.

These materials do not form a fixed grade structure. In Sendzimir and Cluster Mills, material selection is application-driven. Selection of high-chromium tool steels, medium-high alloy tool steels, and Semi-HSS and HSS grades depend on rolling conditions, roll diameter, contact pressure, and the required balance between wear resistance and toughness.

Material Groups

High-Chromium Tool Steel Rolls

High-Chromium Tool Steels are the primary material group for Sendzimir and Cluster Mill Rolls where maximum wear resistance and high surface stability are required under very high contact pressure. They are mainly used for work rolls and, in selected cases, for intermediate rolls where wear resistance is more important than toughness.

These materials are characterized by high carbon and chromium content, resulting in a high carbide volume. They provide very strong wear resistance and surface stability, however, they exhibit lower toughness and higher sensitivity to cracking, grinding damage, and instability. Their effective working layer is relatively limited, but wear resistance within that layer remains very high.

Typical materials include Cr12, Cr12MoV, Cr12MoVCo, Cr12Mo1V1 (D2, 1.2379), and related 12%Cr high-chromium cold-work tool steels.

Medium-High Alloy Tool Steel Rolls

Medium-High Alloy Tool Steels are used where high-chromium tool steels remain too brittle and conventional forged grades are not sufficient. They are used mainly for selected work rolls and intermediate rolls, requiring a more balanced combination of wear resistance and toughness.

Compared with high-chromium tool steels, they provide higher toughness and instability tolerance. They are used where rolling conditions require a more balanced material response.

Typical materials include 5Cr5WMoVSi, 9Cr2Mo, X63CrMoV5-1 (1.2362), 5H12 (H12), selected 8%Cr grades, and related medium-high alloy roll steels.

Semi-HSS and HSS Rolls

Semi-HSS and HSS Rolls are used in selected cases, where a deeper effective working layer with high wear resistance is required. In Sendzimir and Cluster Mills, these materials become more sensitive to rolling stability, cooling consistency, and grinding practice due to smaller roll diameters and much higher localized stress.

They are not typical materials for backup rolls, side-support rolls, or backing bearings (backing assemblies).

Performance Characteristics and Material Selection

Material selection in Sendzimir and Cluster Mills is based on roll function. It depends on contact pressure, roll geometry, rolled product surface requirements, and the required balance between wear resistance and toughness.

This is not a linear upgrade path or a simple increase in alloy content. High-chromium tool steels are selected where maximum wear resistance and surface stability are required. Medium-high alloy tool steels are preferred where improved toughness and higher instability tolerance are needed. Semi-HSS and HSS rolls are used in selected cases where a deeper effective working layer is required.

Sendzimir and Cluster roll material positioning matrix comparing conventional forged rolls, medium-high alloy tool steel rolls, Semi-HSS and HSS rolls, and high-chromium tool steel rolls by wear resistance, surface stability, contact pressure, and process discipline requirement.
Material Family High-Chromium Tool Steel
 Medium-High Alloy Tool Steel Semi-HSS and HSS
Selection Criteria Maximum wear resistance and surface stability Wear resistance and toughness balance
 Deeper effective working layer and higher wear resistance
Hardenability High High Very High
Effective Working Layer Low Medium High
Wear Resistance Very High
 High High to Very High
Toughness Low Medium Low to Medium
Instability Tolerance Low Medium Low
Thermal Crack Resistance Low to Medium Medium
 Medium
Surface Damage Tendency Low Medium Low
Grinding Sensivity High Medium to High High to Very High
Cooling Sensivity High Medium High to Very High
Typical Roll Position Work rolls and selected intermediate rolls Intermediate rolls and selected work rolls Selected work and intermediate rolls

Forged Work Rolls

Sendzimir and Cluster Forged Rolls belong to the broader family of forged rolling mill rolls used in steel  and non-ferrous rolling mills.

Vulcan Metal provides forged rolling mill rolls, including Sendzimir and Cluster Forged Work Rolls, Intermediate Rolls, Idler or Driven Rolls and other forged roll materials, selected according to actual rolling mill conditions and performance requirements.

For additional information, you can also consult our page on Forged Rolling Mill Rolls.

In addition, you may refer to our dedicated pages covering the main forged roll material families:

A large rolling mill roll showing forged and cast rolling mill rolls grades and materials

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