Zhuojin Pipe Fitting Co., LtdDual-Layer Electroslag Surfacing Process for Stainless Steel Using Strip Electrode
Literature Overview
This 1997 research published in "Welding" (焊接), authored by Sun Jianhong and Ye Donglin from the Harbin Welding Research Institute (now part of the Harbin Institute of Technology), presents a comprehensive study on a dual-layer electroslag surfacing process for stainless steel applications. Published in Volume 3 (pages 12-15, ISSN 1001-1382), this work addresses the challenge of depositing high-quality stainless steel surfacing layers with controlled composition and minimal base metal dilution. The research was supported by practical production requirements and has been successfully applied in industrial settings.
Core Technical Innovation
The fundamental innovation in this study is the development of a "one-strip-one-flux" dual-layer electroslag surfacing configuration that exploits the inherently low dilution characteristic of strip electrode electroslag welding (below 10%). The authors recognized that achieving precise alloy composition in the surfacing layer requires minimizing dilution from the base metal, and that electroslag welding with strip electrodes offers this advantage over conventional processes such as submerged arc welding or manual arc welding.
The dual-layer approach addresses a critical practical problem: the first surfacing layer must provide adequate metallurgical bonding with the base metal while the second layer achieves the target stainless steel composition and properties. This separation of functions allows each layer to be optimized independently.
Process Configuration and Material System
| Component | Specification | Function |
|---|---|---|
| Electrode | Domestic standard stainless steel strip | Filler metal source |
| Flux | Special sintered flux SJ602 | Shielding, alloying, slag control |
| Equipment | Domestic strip electrode submerged arc surfacing machine | Process execution |
| Configuration | One-strip-one-flux dual-layer | Composition control |
| Dilution rate | Below 10% | Composition accuracy |
The development of the special sintered flux SJ602 represents a significant contribution to this work. The flux serves multiple functions: providing arc shielding, controlling slag viscosity and fluidity for proper pool shape, adding alloying elements to compensate for dilution effects, and ensuring proper slag-metal separation for clean surfacing layers. The sintered nature of the flux provides consistent composition and particle size distribution, which is critical for reproducible electroslag welding results.
Metallurgical Analysis and Performance Evaluation
The study examines the chemical composition and mechanical properties of both surfacing layers. The first layer, being in direct contact with the base metal, exhibits higher dilution and consequently a composition intermediate between the base metal and the strip electrode. The second layer achieves near-electrode composition due to the low dilution characteristic of electroslag welding.
Key performance indicators evaluated include:
- Hardness distribution through the surfacing layer thickness
- Corrosion resistance of the final surfacing surface
- Metallurgical bond strength at the base metal-surfacing interface
- Absence of defects such as porosity, cracks, and inclusions
The electroslag process produces a characteristic columnar grain structure in the surfacing deposit, which is typical of directional solidification from the bottom of the molten pool. This microstructure provides good properties perpendicular to the surface but may require consideration for through-thickness toughness requirements.
Engineering Application and Process Advantages
The successful production application of this process demonstrates several advantages over conventional surfacing methods:
- High deposition rate: Strip electrode electroslag welding achieves deposition rates 3-5 times higher than conventional submerged arc welding, making it economically attractive for thick surfacing layers.
- Low dilution: The 10% or lower dilution rate ensures accurate control of final surfacing composition, which is critical for corrosion-resistant applications.
- Excellent metallurgical quality: The slow cooling rate of electroslag welding produces fine, uniform microstructures with minimal residual stress.
- Scalability: The process is well-suited for large components requiring extensive surfacing coverage.
For engineers working on stainless steel clad pipe manufacturing, valve body surfacing, and corrosion-resistant equipment repair, this dual-layer electroslag approach offers a proven methodology for achieving high-quality surfacing deposits. The principle of using a transition layer followed by a performance layer is widely applicable and can be adapted to other surfacing applications where composition control is critical.
Key Questions and Study Insights
The research raises important questions about the practical limitations of electroslag surfacing: the process is primarily suitable for horizontal or slightly inclined surfaces, requires specialized equipment, and may not be economical for small or irregularly shaped components. Additionally, the sintered flux SJ602 requires careful handling and storage to maintain its physical properties. Despite these limitations, the fundamental approach of exploiting low-dilution processes for composition-critical surfacing remains a cornerstone principle in modern surfacing technology. The work exemplifies how understanding the metallurgical behavior of a process can lead to innovative process configurations that solve practical engineering problems.