Zhuojin Pipe Fitting Co., LtdApplication of Roll Surfacing Welding Technology at Tianjin Rolling No. 3
Literature Overview
This 1993 paper by Li Caihua, published in "Tianjin Metallurgy" (No. 4, pp. 16–18), documents the practical application of roll surfacing welding technology at Tianjin Rolling No. 3, a major steel rolling mill in China. The paper covers the selection of welding materials, optimization of process parameters, and operational results of surfacing welding applied to rolling mill rolls. This work is particularly relevant to metallurgical engineers and maintenance personnel in the steel industry who seek to extend roll life and reduce production costs through surface engineering techniques.
Background and Technical Challenges
Rolling mill rolls are subjected to extreme operating conditions including high contact pressure, cyclic thermal loading, abrasive wear from steel work, and chemical attack from scale and lubricants. These combined factors lead to progressive degradation of the roll surface, manifested as wear, cracking, spalling, and dimensional deviation. Traditional approaches to roll maintenance include periodic regrinding to restore geometry, replacement of worn rolls, or use of monolithic alloy rolls with inherently longer life. Surfacing welding offers an alternative by applying a wear-resistant alloy layer to the roll surface, combining the economic benefits of a low-cost base roll with the performance advantages of a hardfacing alloy surface.
Welding Material Selection and Process Parameters
The study addressed the critical issue of welding material selection for roll surfacing, considering the specific operating conditions at Tianjin Rolling No. 3. The selection criteria included hardness of the deposited layer, toughness to resist spalling, resistance to thermal cracking, and compatibility with the base roll steel.
| Welding Material Category | Typical Composition | Application |
|---|---|---|
| High-Cr hardfacing | Cr 20–30%, C 2–4% | Hot work wear, scale resistance |
| High-Mo hardfacing | Mo 10–20%, Cr 5–10% | Abrasive wear, high temperature |
| Ni-based hardfacing | Ni 60–80%, Cr 5–15% | Corrosion and abrasion combined |
| Co-based hardfacing | Co 60–70%, Cr 10–20% | Extreme wear, high temperature |
The process parameters optimized in the study included welding current, travel speed, number of passes, and preheating temperature. The authors emphasized that the interpass temperature must be carefully controlled to prevent excessive grain growth in the deposited layer, which would reduce hardness and wear resistance. Preheating of the roll to 200–300 °C was recommended to reduce thermal stress and minimize the risk of cracking in the HAZ.
Operational Results and Quality Control
The operational results demonstrated that surfacing-welded rolls achieved significantly extended service life compared to standard rolls, with wear rates reduced by a substantial margin. The authors reported that the surfacing layer maintained its hardness after prolonged operation, indicating good resistance to abrasive and adhesive wear under actual rolling conditions. Quality control measures included hardness testing of the deposited layer, visual inspection for surface defects, and dimensional verification after welding to ensure roll geometry met specification.
The study also addressed the issue of roll balance after surfacing, noting that symmetric application of the surfacing layer is essential to maintain dynamic balance at operating speeds. Any asymmetry in deposited mass can induce vibration that affects product quality and accelerates bearing wear. The authors recommended that roll balancing be performed after surfacing welding and before installation in the mill.
Engineering Practice and Reflections
The application of roll surfacing welding at Tianjin Rolling No. 3 exemplifies the successful integration of surface engineering technology into industrial practice. The study demonstrates that careful selection of welding materials, disciplined process control, and rigorous quality assurance can yield substantial improvements in roll life and production efficiency. The economic benefits are significant, as extended roll life reduces the frequency of roll changes, decreases downtime, and lowers the overall cost of roll maintenance.
A key reflection from this study is that surfacing welding technology, while well-established in principle, requires careful adaptation to the specific operating conditions of each mill. Factors such as rolling temperature, work material, roll diameter, and mill speed all influence the wear mechanism and therefore the appropriate surfacing alloy and process parameters. Engineers should approach roll surfacing as a systematic engineering task, involving failure analysis, material selection, process development, pilot testing, and full-scale validation, rather than as a simple repair operation.
Conclusion
The application of roll surfacing welding technology at Tianjin Rolling No. 3 provides a valuable case study for metallurgical engineers seeking to extend roll life and improve production efficiency through surface engineering. The documented results confirm that surfacing welding, when applied with proper material selection, process optimization, and quality control, offers a reliable and cost-effective solution to roll wear problems in steel rolling mills. This work reinforces the importance of surface engineering as a core technology in the steel industry and encourages engineers to adopt a systematic, metallurgically informed approach to roll maintenance and surface protection.