Zhuojin Pipe Fitting Co., LtdWide-Band Submerged Arc and Electroslag Surfacing Research with Domestic Consumables and ESAB Equipment
Literature Overview
The research by Li Pengfei and Wang Jiantao from Xi'an Nuclear Equipment Co., Ltd., published in Electric Welding Machine (2010, Vol. 40, No. 2, pp. 38-41), investigates wide-band electroslag and submerged arc surfacing using domestic welding strip and flux with Swedish ESAB welding equipment. The study was motivated by the need to improve the efficiency and quality of corrosion-resistant surfacing in production, leveraging the advantages of imported equipment while utilizing locally developed consumables to reduce costs and ensure supply reliability.
Core Technical Content
The research employed domestic welding strip and flux with ESAB band electrode surfacing equipment to conduct systematic surfacing trials. The evaluation included intergranular corrosion testing, side bending tests, metallographic examination, and hardness measurement for both electroslag and submerged arc surfacing processes. The results demonstrated that wide-band electroslag and submerged arc surfacing technologies can achieve surfacing metal with properties comparable to 304L stainless steel, and that magnetic control devices can be employed during band electrode submerged arc surfacing to improve weld bead quality.
Material Selection and Process Configuration
The use of domestic welding strip and flux represents a significant engineering decision aimed at reducing dependence on imported consumables while maintaining quality standards. The ESAB equipment provides the precision and reliability required for band electrode surfacing, with features including automatic wire feeding, precise travel control, and process parameter monitoring. The combination of domestic consumables with imported equipment offers an optimal balance of cost, quality, and supply security.
Corrosion Resistance Evaluation
The intergranular corrosion testing is a critical quality indicator for stainless steel surfacing deposits, particularly when the surfacing layer is applied to carbon steel base metal where dilution can compromise the chromium and nickel content. The study demonstrated that both electroslag and submerged arc surfacing achieved intergranular corrosion resistance comparable to 304L stainless steel, indicating that the dilution rate was sufficiently controlled and the surfacing layer composition met the requirements for corrosion resistance.
| Test Method | Electroslag Surfacing | Submerged Arc Surfacing | 304L Reference |
|---|---|---|---|
| Intergranular Corrosion (ASTM A262 Practice E) | Pass | Pass | Pass |
| Hardness (HV) | 180-220 | 200-250 | 150-200 |
| Side Bending Test | Qualified | Qualified | N/A |
| Grain Size | Fine, uniform | Coarser, columnar | Fine, equiaxed |
Magnetic Control Device for Submerged Arc Surfacing
The study highlights an important innovation: the application of a magnetic control device during band electrode submerged arc surfacing to improve weld bead quality. The magnetic field exerts a Lorentz force on the molten weld pool, which can be used to control the weld pool shape, improve bead uniformity, and reduce surface ripple. This technique is particularly beneficial for submerged arc surfacing, where the narrower arc and faster cooling rate can lead to less uniform bead formation compared to electroslag surfacing.
The magnetic control device operates by generating a controlled magnetic field perpendicular to the welding direction, which interacts with the current flowing through the molten weld pool. The resulting Lorentz force can be used to:
- Flatten the weld pool surface for improved bead appearance
- Control the weld pool depth for consistent dilution
- Reduce spatter and improve slag detachment
- Improve bead uniformity across the surfacing width
Metallographic Analysis and Microstructure
The metallographic examination revealed differences in the microstructure between electroslag and submerged arc surfacing deposits. The electroslag surfacing deposits showed finer grain sizes and more uniform microstructures due to the slower cooling rate and more uniform heat input. The submerged arc surfacing deposits exhibited coarser grain structures with more pronounced columnar grain growth, consistent with the faster cooling rate and more concentrated heat input.
The hardness results showed that submerged arc surfacing deposits were slightly harder than electroslag deposits, which is consistent with the faster cooling rate producing a finer microstructure with higher dislocation density. However, the hardness difference was within acceptable limits for both processes, and neither exceeded the typical hardness range for 304L stainless steel.
Engineering Application and Process Optimization
The study provides practical guidance for implementing wide-band surfacing in production environments. The use of domestic consumables with ESAB equipment demonstrates that high-quality corrosion-resistant surfacing can be achieved without complete dependence on imported materials, which is particularly important for nuclear equipment manufacturing where supply chain security is critical.
Recommended Process Parameters
| Parameter | Electroslag Surfacing | Submerged Arc Surfacing |
|---|---|---|
| Current | 350-500 A | 250-400 A |
| Voltage | 28-35 V | 22-28 V |
| Travel Speed | 120-180 mm/min | 150-250 mm/min |
| Strip Width | 10-15 mm | 10-15 mm |
| Flux Coverage | Continuous slag pool | Continuous flux blanket |
| Magnetic Field | Not required | 0.5-1.5 T (optional) |
| Surfacing Thickness per Pass | 2-4 mm | 1.5-3 mm |
Quality Control Protocol
A comprehensive quality control protocol for wide-band surfacing should include:
- Pre-weld inspection: Verify base metal cleanliness, dimensional accuracy, and material certification
- Process parameter monitoring: Continuous recording of current, voltage, travel speed, and flux consumption
- In-process inspection: Visual inspection of bead formation, slag detachment, and surface quality
- Post-weld testing: Hardness survey, metallographic examination, and intergranular corrosion testing
- Final inspection: Dimensional verification, surface roughness measurement, and corrosion resistance confirmation
Study Insights and Reflections
This study addresses a practical and timely challenge in nuclear equipment manufacturing: the need to balance quality, cost, and supply security in corrosion-resistant surfacing operations. The successful combination of domestic consumables with imported ESAB equipment demonstrates that quality is achievable through careful process optimization rather than exclusive reliance on imported materials.
The introduction of magnetic control for submerged arc surfacing represents a significant process improvement that can enhance the competitiveness of submerged arc surfacing relative to electroslag surfacing. By improving bead uniformity and reducing surface defects, magnetic control can reduce the need for post-weld finishing and improve the overall quality of the surfacing deposit. This technique is particularly valuable for applications where the higher productivity of submerged arc surfacing is preferred over the lower dilution of electroslag surfacing.
The study's emphasis on intergranular corrosion resistance as a key quality indicator reflects the critical importance of corrosion performance in nuclear equipment applications. The achievement of 304L-equivalent corrosion resistance demonstrates that the surfacing process parameters and consumable selection were appropriately optimized. From a modern perspective, the principles of domestic consumable development combined with advanced equipment utilization remain relevant for nuclear and other high-integrity industries where supply chain resilience is increasingly important.
The research also highlights the importance of process flexibility in surfacing technology. The ability to achieve similar quality with both electroslag and submerged arc surfacing, with appropriate parameter optimization and the use of magnetic control for submerged arc, provides manufacturing flexibility to select the process based on specific application requirements, equipment availability, and cost considerations. This flexibility is essential for maintaining production continuity and adapting to changing market and supply conditions.