Zhuojin Pipe Fitting Co., LtdDevelopment and Application of 347 Stainless Steel Wire-Electrode Submerged Arc Surfacing Materials
Literature Overview
This paper by Wang Jinguang, Hu Xihai, Che Hong, Jia Lijuan, Wang Dong, Zou Liwei, Xu Kai, and Zhang Yimei (2011), published in Welding (No. 6), reports on the development and industrial application of 347 stainless steel wire-electrode submerged arc surfacing materials. The research was conducted through a collaboration between China Petrochemical Engineering Corporation, Fushun Machinery Equipment Manufacturing Co., Ltd., and the Harbin Welding Research Institute. The work addressed specific limitations of conventional SMAW surfacing for stainless steel components in the petrochemical industry.
Technical Problem Statement
The development was driven by several practical limitations of using stainless steel SMAW electrodes for surfacing operations in pressure vessel manufacturing:
| Limitation | Impact |
|---|---|
| Low deposition rate (SMAW: 1–2 kg/h) | Extended production cycle time |
| Poor surface quality of deposited beads | Requires extensive post-weld grinding |
| High material cost per unit deposition | Increased manufacturing cost |
| Inconsistent bead profile | Difficulty achieving uniform thickness |
| Operator fatigue and skill dependency | Quality variability |
These limitations were particularly problematic for large-diameter pressure vessels and heat exchangers where extensive surfacing areas require high deposition rates to maintain production schedules. The wire-electrode submerged arc welding (SAW) process offered the potential to address these issues, but required the development of compatible consumables.
Material Development
The developed material system consists of:
Wire Electrodes:
- H309SL: Austenitic stainless steel wire with composition matching E309L (22% Cr, 13% Ni, low carbon)
- H347SL: Austenitic stainless steel wire with composition matching E347 (18% Cr, 11% Ni, 0.75% Nb, low carbon)
Fluxes:
- SJ661: Matching flux for H309SL wire
- SJ667: Matching flux for H347SL wire
The "L" designation indicates low carbon content (≤ 0.03% C), which is critical for preventing intergranular corrosion in sensitized conditions. The H347SL wire contains niobium stabilization (0.75% Nb) to prevent chromium carbide precipitation at grain boundaries during high-temperature service.
Performance Comparison
The paper presents a comprehensive comparison between SMAW and wire-electrode SAW surfacing:
| Performance Metric | SMAW (E309L/E347L) | Wire-Electrode SAW (H309SL/H347SL + SJ661/SJ667) |
|---|---|---|
| Deposition rate | 1.0–1.5 kg/h | 3.0–4.5 kg/h |
| Deposition efficiency | 70–80% | 85–92% |
| Surface quality | Rough, requires grinding | Smooth, minimal finishing |
| Bead profile consistency | Variable (operator dependent) | Consistent (process controlled) |
| Cost per kg deposited | 1.8–2.2× baseline | 1.0× baseline |
| Dilution rate | 15–25% | 10–18% |
The wire-electrode SAW process achieved deposition rates approximately 3 times higher than SMAW, with improved surface quality and reduced post-weld processing requirements. This translates directly to production cycle time reduction and cost savings.
Metallurgical Properties of Deposited Metal
The deposited metal properties achieved with the developed material system:
H309SL Deposited Metal:
- Tensile strength: 580–620 MPa
- Yield strength: 310–350 MPa
- Elongation: 35–40%
- Hardness: 180–210 HV
- Intergranular corrosion: Pass (ASTM A262 Practice 1E)
H347SL Deposited Metal:
- Tensile strength: 560–600 MPa
- Yield strength: 300–340 MPa
- Elongation: 33–38%
- Hardness: 175–205 HV
- Intergranular corrosion: Pass (ASTM A262 Practice 1E)
- Sensitization resistance: Superior (Nb stabilization)
Both deposited metals exceeded the mechanical property requirements specified in ASME B31.3 and ASTM A234 for stainless steel pressure vessel components.
Industrial Application
The developed materials have been successfully applied in the manufacturing of:
- Petrochemical pressure vessels: Reactor shells and heat exchanger shells requiring corrosion-resistant internal surfacing.
- Process piping components: Large-diameter pipe spools with internal corrosion-resistant overlays.
- Storage tanks: Internal surfacing of carbon steel tanks storing aggressive chemical media.
- Heat exchanger tubesheets: Multi-layer surfacing to achieve required corrosion resistance with controlled dilution.
The application in petrochemical pressure vessel manufacturing demonstrated that the wire-electrode SAW process could achieve overall performance comparable to strip-electrode SAW, while offering greater flexibility for smaller components and more complex geometries.
Engineering Significance and Process Integration
This work represents a significant advancement in stainless steel surfacing technology for the petrochemical industry. The key innovations include:
- Process substitution: Replacing SMAW with wire-electrode SAW for improved efficiency without sacrificing quality.
- Material matching: Developing flux compositions (SJ661, SJ667) that maintain the austenitic microstructure and corrosion resistance of the deposited metal.
- Low-carbon control: Achieving consistent low carbon content in deposited metal through careful flux chemistry and process parameter control.
From a process integration perspective, the transition from SMAW to wire-electrode SAW requires changes to the production workflow:
- Equipment: Requires submerged arc welding machines with wire feed capability (vs. manual electrode holders).
- Flux handling: Requires flux drying, storage, and recovery systems.
- Joint preparation: Requires precise edge preparation and fit-up for automated welding.
- Inspection: Requires flux removal and thorough surface preparation before NDT.
These changes represent an investment in capital equipment and process infrastructure, but the productivity gains typically justify the investment within 12–18 months for high-volume production.
Key Reflections and Insights
The most significant insight from this work is the demonstration that wire-electrode SAW can achieve performance equivalent to strip-electrode SAW for stainless steel surfacing applications. This finding opens up the SAW process for a broader range of component sizes and geometries, as strip electrodes require larger equipment and are less adaptable to curved or small-diameter components.
The development also highlights the importance of flux chemistry in submerged arc welding. The flux is not merely a shielding and slag-forming medium—it actively controls the composition, microstructure, and properties of the deposited metal. The development of SJ661 and SJ667 fluxes required extensive metallurgical experimentation to achieve the desired composition transfer and microstructural control.
From a quality assurance perspective, the transition to wire-electrode SAW introduces new quality considerations: flux consistency between batches, wire composition uniformity, and process parameter stability. These require robust incoming inspection and in-process monitoring systems.
This literature provides a comprehensive case study in materials development and process optimization for industrial welding applications, demonstrating the integration of metallurgical research, process engineering, and production implementation in solving practical manufacturing challenges.