Zhuojin Pipe Fitting Co., LtdDevelopment and Application of Hardfaced Composite Rollers for Continuous Casting at Pangang
Literature Overview
The paper by Li Dadong, Lin Jiandong, Sun Jingming, Xu Zichao, Li Zaiyou, Liu Weizhong, Yao Chengbao, and Qiu Daorong (1999), published in Iron Steel Vanadium Titanium, reports on the development and industrial application of hardfaced composite rollers for continuous casting machines at Pangang. The authors employed single-wire submerged arc welding (SAW) technology to hardface 15CrMo roller cores, achieving a 3 to 6 times improvement in service life compared to conventional 15CrMo solid rollers. This represents a significant engineering achievement in extending the operational life of critical continuous casting components.
Core Technical Content
Background and Design Philosophy
Continuous casting rollers operate under extreme conditions characterized by high temperatures (up to 1200–1500 °C in the secondary cooling zone), thermal cycling, mechanical loading from the weight of the cast strand, and chemical interaction with molten steel and slag. Conventional 15CrMo steel rollers suffer from rapid wear, thermal cracking, and erosion, requiring frequent replacement that interrupts casting operations. The composite roller concept addresses this challenge by combining a tough, ductile base material (15CrMo) with a wear-resistant, heat-resistant hardfacing surface layer, creating a functionally graded structure that optimizes both toughness and surface durability.
Hardfacing Process Development
The authors selected single-wire submerged arc welding as the hardfacing process based on its maturity, reproducibility, and ability to achieve consistent deposition quality. The development process followed a systematic approach: laboratory comparison of 15CrMo base metal and hardfacing metal properties, optimization of welding parameters, and industrial validation through full-scale roller testing.
| Parameter | Optimized Value | Purpose |
|---|---|---|
| Welding current | 400–500 A | Adequate penetration and deposition rate |
| Welding voltage | 30–36 V | Stable arc and consistent bead profile |
| Travel speed | 200–300 mm/min | Control heat input and bead geometry |
| Preheat temperature | 300–400 °C | Reduce residual stress and prevent base metal cracking |
| Number of passes | 3–5 | Build up to required surface profile |
| Post-weld stress relief | 600–650 °C for 2 h | Reduce residual stress to acceptable levels |
The hardfacing alloy was selected to provide high hardness (HRC 45–55), good thermal shock resistance, and adequate toughness to resist cracking during thermal cycling. The microstructure of the deposit, consisting primarily of martensite with dispersed carbides, provides the necessary combination of hardness and wear resistance while maintaining sufficient ductility to accommodate thermal expansion differences between the deposit and the base metal.
Performance Validation
The industrial trial demonstrated that the hardfaced composite rollers achieved a service life 3 to 6 times greater than conventional 15CrMo rollers. This improvement was attributed to the superior wear resistance of the hardfacing layer, which reduced surface erosion and thermal cracking. The authors also reported that the composite rollers maintained dimensional stability throughout their service life, with minimal profile degradation compared to solid rollers.
Engineering Practice Integration
The composite roller concept has broad applicability in pipe and tube manufacturing, particularly for mill rolls in the seamless pipe production process. In the plug mill, the plug and rolls experience extreme mechanical and thermal loading, and the use of hardfaced composite rolls can significantly extend service intervals. Similarly, in the finishing mill of a tube mill, the work rolls that contact hot tube at temperatures above 800 °C would benefit from hardfacing with heat-resistant alloys.
The systematic development approach described in the paper—laboratory characterization, parameter optimization, and industrial validation—represents a best practice model for hardfacing engineering. This approach minimizes the risk of full-scale failure and provides a clear technical basis for process specification. The use of FMEA (Failure Mode and Effects Analysis) can be applied at each stage of development to identify potential failure modes, such as cracking, spalling, or insufficient bond strength, and to implement preventive measures.
Key Reflections and Implications
This paper demonstrates that the strategic application of hardfacing technology can transform the economics of heavy equipment maintenance. The 3 to 6 times life extension achieved through composite roller design represents a substantial reduction in replacement frequency, downtime, and spare parts inventory requirements. For pipe manufacturing engineers, the lesson is that hardfacing should be considered not as a repair technique but as a design tool for creating functionally optimized components. The systematic development methodology presented here—combining metallurgical characterization, process optimization, and industrial validation—provides a replicable framework for implementing hardfacing solutions in any heavy equipment application.