Surfacing Repair Process of Continuous Casting Rolls

Literature Overview

This technical paper by Miao Hailiang from the Repair Center of Tianjin Second Metallurgical Machinery Factory, published in Welding Technology (1995, Vol. 24, No. 4, p. 21), presents a practical engineering solution for the repair and refurbishment of continuous casting rolls—a critical component in steel production. The paper reports that advanced surfacing technology with flux-cored wire and flux can extend the service life of repaired rolls by 2-3 times compared to new rolls, while significantly improving high-temperature strength and wear resistance.

Technical Background and Challenge

Continuous casting rolls operate under extremely severe conditions:

• Temperature: Surface temperatures reach 1200-1400°C in contact with molten steel
• Thermal cycling: Rapid heating and cooling during each casting cycle
• Mechanical load: Contact pressure from solidifying shell
• Chemical attack: Oxidation, sulfidation, and steel pickup
• Abrasive wear: From inclusions and scale in the steel

The conventional approach of replacing worn rolls with new ones is economically unfavorable given the high cost of roll manufacturing and the availability of sound roll cores. Surfacing repair offers a cost-effective alternative that preserves the investment in the roll body while restoring the functional surface layer.

Surfacing Process Description

The repair process employs flux-cored wire arc surfacing with the following process parameters:

The key advantage of flux-cored wire surfacing over solid wire processes is the higher deposition rate and the ability to alloy the weld metal through the flux composition. The flux provides shielding, deoxidation, and alloying elements that can be tailored for high-temperature performance.

Performance Results and Economic Analysis

The reported performance improvements demonstrate significant engineering value:

• Service life extension: 2-3 times that of new rolls
• High-temperature strength: Substantially improved through proper alloy composition
• Wear resistance: Enhanced by hardening phase formation in the surfacing layer
• Cost savings: Significant reduction in roll replacement frequency and downtime

The economic benefit is compounded by reduced production downtime during roll changeovers, which is a major cost factor in continuous casting operations where even short interruptions result in significant production losses.

Engineering Reflections

This paper represents the practical application of surfacing technology in a demanding industrial environment. For engineers managing continuous casting operations, the key lessons include:

1. Process selection matters: Flux-cored wire processes offer superior deposition rates and alloying flexibility compared to solid wire processes for large-area surfacing applications.
2. Thermal management is critical: Preheating and interpass temperature control prevent cracking in the thick surfacing layers while maintaining adequate hardness in the final layer.
3. Multi-pass strategies: Building up the surfacing layer in multiple passes allows for optimized microstructure and reduces residual stress accumulation.
4. Quality verification: Post-repair inspection including hardness profiling, surface roughness measurement, and dimensional checking ensures the repaired roll meets operational requirements.

The approach described here has evolved significantly since 1995, with modern implementations incorporating plasma transferred arc (PTA) surfacing, laser cladding, and automated multi-wire systems. However, the fundamental principles of process parameter optimization, thermal management, and material selection remain unchanged. For facilities without access to advanced equipment, the flux-cored wire approach described remains a viable and cost-effective solution for roll refurbishment.