Application of Roll Cladding Technology at Tianjin No.3 Rolling Mill

Literature Overview and Background

This 1993 publication by Li Caihua documents the application of roll cladding technology at the Tianjin No.3 Rolling Mill, a major steel production facility in northern China. Rolling mill rolls are among the most heavily utilized components in steel production, enduring extreme conditions of high temperature, high contact stress, and abrasive wear during the rolling of hot steel slabs and billets. The adoption of cladding technology at this facility represents a significant engineering initiative to improve roll service life, reduce maintenance costs, and enhance production efficiency.

Rolling Mill Roll Service Environment

Rolling mill rolls operate under some of the most severe conditions found in industrial manufacturing. During hot rolling, the roll surface is in continuous contact with steel at temperatures of 900 to 1200 degrees Celsius, while the contact stress can reach 2000 to 3000 MPa. The rolling speed can exceed 10 m/s, creating a high sliding velocity that generates significant frictional heating and wear. The combination of these parameters creates a complex failure environment involving thermal fatigue, abrasive wear, adhesive wear, and plastic deformation.

Roll Failure Modes and Their Contributions

The base material of the rolling mill rolls is typically a high-chromium cast iron (HCIC) with a composition of 5 to 8 percent chromium, 0.8 to 1.2 percent carbon, and 0.3 to 0.6 percent molybdenum. This material provides good wear resistance and thermal stability but may not be sufficient for the most demanding rolling applications, particularly for finish rolling where surface quality requirements are stringent.

Cladding Process and Material Selection

The study evaluated multiple cladding processes and materials for different roll types used at the Tianjin No.3 Rolling Mill. The primary processes considered were submerged arc welding (SAW) overlay, electroslag welding (ESW) overlay, and plasma transferred arc (PTA) cladding. Each process was selected based on the specific roll type, required overlay thickness, and production schedule requirements.

Process Selection by Roll Type

The material selection followed a systematic approach based on the specific failure mode dominant in each roll position. Roughing rolls, which experience the most severe abrasive wear from scale and oxide particles, were clad with high-carbon, high-chromium cast iron alloys that provide maximum hardness and abrasion resistance. Finish rolls, where surface quality of the rolled product is critical, were clad with nickel-based alloys that provide a smooth, wear-resistant surface with excellent resistance to thermal fatigue cracking.

Process Parameters and Quality Control

The cladding process parameters were optimized through experimental trials and field validation. The following table summarizes the key parameters for each cladding process employed at the facility.

Optimized Cladding Parameters