CLADDING TECHNOLOGY SHANXI CO., LTDStrip Cladding Technology Application in Industrial Practice
Literature Overview
This topic addresses the practical application of strip cladding (weld overlay) technology, associated with ESAB welding and cutting equipment (Shanghai) Co., Ltd., published in 2010. Strip cladding, also known as submerged arc welding (SAW) overlay using strip electrodes, represents one of the most efficient and economical methods for producing clad plate and extending the service life of carbon steel and low-alloy steel components in aggressive chemical environments. The reference to ESAB—a globally recognized welding consumables manufacturer—signals that the study draws upon industry-standard wire and strip electrode systems, particularly those designed for automated or mechanized SAW overlay processes.
Core Technical Principles
Strip cladding operates on the principle of depositing a corrosion-resistant or wear-resistant layer onto a structural base material through a continuous submerged arc welding process. The strip electrode, typically 12 mm to 16 mm wide and 1.5 mm to 2.5 mm thick, is fed continuously into the arc pool while a flux blanket shields the weld from atmospheric contamination. The process achieves high deposition rates—commonly 6 kg/h to 15 kg/h depending on current and travel speed—making it significantly more productive than consumable electrode processes such as SMAW or FCAW for large-area overlay applications.
The metallurgical integrity of the cladding depends critically on achieving a sound metallurgical bond between the overlay layer and the base metal without excessive dilution. The dilution ratio—the proportion of base metal alloying elements entering the overlay—is typically controlled between 5% and 15% for stainless steel overlays on carbon steel substrates. Excessive dilution degrades the corrosion resistance of the overlay by lowering chromium and nickel equivalents below the threshold required for passive film stability.
Key Process Parameters
The following table summarizes the typical process window for strip cladding as applied in industrial settings:
| Parameter | Typical Range | Influence |
|---|---|---|
| Welding current | 600 A – 1200 A | Higher current increases penetration and dilution |
| Arc voltage | 28 V – 36 V | Controls arc stability and heat input |
| Travel speed | 300 mm/min – 800 mm/min | Affects deposition rate and bead geometry |
| Flux coverage | 15 mm – 25 mm | Ensures adequate shielding and slag protection |
| Strip electrode width | 12 mm – 16 mm | Determines bead width and overlap |
| Base metal preheat | 100 °C – 250 °C | Reduces cracking susceptibility in high-carbon base metals |
| Interpass temperature | < 250 °C (for austenitic SS) | Prevents sensitization and grain coarsening |
Engineering Practice Considerations
In practical applications, strip cladding is most commonly employed for the fabrication of stainless steel-lined carbon steel pressure vessels, heat exchanger shells, and storage tanks operating in sulfuric acid, hydrochloric acid, or alkaline environments. The process is particularly advantageous for large-diameter cylindrical components where mechanized or orbital cladding equipment can be deployed efficiently.
One critical engineering challenge involves managing the residual stresses introduced during multi-pass cladding. The thermal cycle generates significant compressive stresses in the overlay layer and tensile stresses in the base metal near the fusion boundary. For pressure vessels subject to internal pressure cycling, these residual stresses may interact with operational stresses to accelerate fatigue crack initiation. Post-weld heat treatment (PWHT) at 600 °C to 650 °C for carbon steel substrates, or solution annealing at 1050 °C to 1100 °C for austenitic stainless steel overlays, is often required to relieve these stresses.
Common Defects and Countermeasures
- Cracking at the fusion boundary: Caused by high carbon equivalent of the base metal or excessive cooling rate. Countermeasure: increase preheat temperature, reduce travel speed, or use a low-dilution wire configuration.
- Undercut and incomplete fusion: Result from insufficient current or excessive travel speed. Countermeasure: optimize the current-to-speed ratio and ensure proper joint preparation.
- Porosity in the overlay layer: Often associated with moisture-contaminated flux or inadequate flux coverage. Countermeasure: implement strict flux drying protocols and maintain consistent flux blanket depth.
- Overlay spalling: Occurs when the bond strength between overlay and base is insufficient. Countermeasure: ensure proper cleaning of the base surface and verify metallurgical compatibility.
Study Insights
The ESAB reference in this topic underscores the importance of consumable selection in strip cladding applications. Different strip electrode compositions—such as 309L, 316L, or 309/316L dual-wire configurations—offer distinct corrosion resistance profiles tailored to specific service environments. Engineers must carefully match the strip electrode chemistry to the anticipated corrosive medium, considering factors such as chloride ion concentration, temperature, and flow velocity. The strip cladding method remains a cornerstone of clad plate manufacturing due to its combination of high productivity, consistent quality, and relatively low cost per unit area compared to explosion cladding or roll-bonded cladding alternatives.