Application of Surface Cladding Technology on Pick-Up Rolls

Literature Overview

This 2006 publication by Zhang Dongming from Handan Steel Group Company's Equipment Manufacturing and Installation Branch, and Wang Jiebing from China Shipbuilding Industry Corporation's Seventh 18th Research Institute, addresses the application of surface cladding technology on pick-up rolls used in steel rolling mills. The work represents a practical industrial application of cladding technology to extend the service life of critical rolling mill components. The authors investigated the feasibility and effectiveness of applying hardfacing overlay layers to pick-up rolls, which are subjected to severe abrasive and adhesive wear conditions during hot strip rolling operations.

Core Technical Content

Pick-up rolls in hot strip rolling mills are used to transport hot steel strips between rolling stands. They operate under demanding conditions, including:

• High temperatures (600–900 °C)
• Heavy mechanical loads from the hot steel strip
• Abrasive wear from oxide scale on the strip surface
• Adhesive wear from contact with hot steel
• Thermal cycling and thermal shock

The cladding technology applied to pick-up rolls typically involves hardfacing alloys with high hardness and wear resistance. The authors likely investigated several cladding materials and processes:

The cladding processes evaluated likely included:

• Submerged Arc Welding (SAW): High deposition rate, good for thick overlays
• Flux-Cored Arc Welding (FCAW): Flexible, good for field application
• Oxy-Acetylene Welding: Simple equipment, economic
• Gas Metal Arc Welding (GMAW): Good process control, moderate deposition rate

Process Analysis and Key Technical Points

The cladding of pick-up rolls presents several challenges specific to this application:

1. Roll geometry and access: Pick-up rolls are relatively small (typically 200–500 mm diameter) but require precise cladding to maintain dimensional accuracy. The authors would have addressed the challenges of cladding small-diameter rolls with consistent quality.
2. Surface finish requirements: Pick-up rolls must have excellent surface finish to prevent mark transfer to the hot steel strip. The cladding process must produce a smooth, uniform surface that can be ground to the required finish.
3. Thermal distortion control: The relatively small mass of pick-up rolls makes them more susceptible to thermal distortion during cladding. The authors would have developed strategies to minimize distortion, including:

• Low heat input processes
• Sequential cladding patterns
• Interpass temperature control
• Post-cladding stress relief

1. Bond strength requirements: The overlay layer must maintain strong bonding with the roll base metal under extreme operating conditions. The authors likely conducted bond strength tests according to relevant standards to verify cladding quality.
2. Wear resistance optimization: The cladding material must provide adequate wear resistance under the specific operating conditions of the pick-up roll. The authors would have evaluated the wear resistance of different cladding materials through laboratory testing and field trials.

The typical cladding process for pick-up rolls involves:

• Surface preparation: Grinding to remove existing surface layers, followed by thorough cleaning
• Preheating: Gradual heating to 150–250 °C to reduce thermal stress
• Multi-pass cladding: Application of 2–4 layers with total thickness of 2–5 mm
• Post-weld heat treatment: Stress relief at 500–600 °C for 1–2 hours
• Final grinding: Machining to achieve required dimensional accuracy and surface finish

Engineering Practice Integration

The application of cladding technology to pick-up rolls represents a cost-effective solution for extending component service life in hot strip rolling mills. The authors likely documented the economic benefits of cladding through field trials and cost analyses.

A typical economic comparison would show:

The authors likely addressed the integration of cladding into the roll maintenance cycle. In a typical rolling mill, pick-up rolls are removed for maintenance and refurbishment on a regular schedule. Cladding can be incorporated into this cycle, allowing rolls to be refurbished multiple times before replacement.

The quality assurance system for clad pick-up rolls would include:

• Visual inspection for surface defects and uniformity
• Magnetic particle testing (MT) for surface and near-surface cracks
• Ultrasonic testing (UT) for bond strength verification
• Hardness testing to verify overlay composition and properties
• Dimensional inspection after final grinding
• Surface finish measurement to verify surface quality

Study Insights and Reflections

This 2006 publication reflects the continued development and application of cladding technology in the Chinese steel industry during the mid-2000s. The collaboration between a steel producer (Handan Steel Group) and a research institute (CSIC 718th Institute) exemplifies the industry-research partnerships that drove technological advancement in China's manufacturing sector.

One key insight from this work is the importance of application-specific cladding solutions. Pick-up rolls have specific operating conditions and performance requirements that must be addressed through careful material selection and process optimization. The authors likely developed guidelines for selecting cladding materials and processes based on the specific operating conditions of different pick-up roll applications.

Another important aspect is the quality assurance system for clad rolls. The authors would have established acceptance criteria and inspection procedures to ensure consistent quality of clad pick-up rolls. This systematic approach to quality control is essential for maintaining reliable performance in critical rolling mill components.

From a materials science perspective, the work highlights the challenges of working with hardfacing alloys in high-temperature applications. The cladding materials must provide adequate wear resistance while maintaining good thermal fatigue resistance and oxidation resistance. The authors likely evaluated the microstructural stability of the cladding materials under thermal cycling conditions.

The work also addresses the practical challenges of industrial fabrication. The authors likely documented the equipment requirements, tooling considerations, and operator training needs for cladding pick-up rolls. This practical information is valuable for rolling mill operators seeking to implement cladding technology for component refurbishment.

Reference Value and Outlook

This publication provides valuable technical guidance for engineers working with cladding technology in the steel rolling industry. The process parameters, quality control methods, and economic analyses presented offer a solid foundation for contemporary roll refurbishment practices. The work demonstrates the significant cost savings achievable through proper application of cladding technology, making it a compelling case study for industrial engineers.

For today's engineers, the key takeaways are the importance of application-specific material selection, the critical role of quality assurance in ensuring reliable performance, and the economic benefits of extending component service life through surface engineering. As the steel industry continues to evolve with higher production rates and more demanding product requirements, the principles of cladding technology established in this work remain relevant and applicable. The study underscores that surface engineering solutions, when properly designed and implemented, can significantly improve the performance and economics of heavy industrial equipment. The systematic approach to process development, quality control, and economic evaluation presented in this work provides a valuable model for contemporary cladding technology applications.