CLADDING TECHNOLOGY SHANXI CO., LTDHigh-Efficiency Strip Electrode Cladding of Low-Carbon Steel
Literature Overview
This paper by Chen Baohua, published in the journal Welding in 1991 from Shanghai Power Plant Auxiliary Machinery Factory, documents the development and application of high-efficiency strip electrode cladding technology for low-carbon steel components. Strip electrode cladding represents one of the oldest yet continuously evolving welding overlay techniques, where a flat ribbon of filler metal (typically 5–25 mm wide) is fed into an electric arc generated between a consumable electrode (often a copper or graphite rod) and the substrate. The technology gained particular importance in power plant applications where large surface areas of carbon steel require corrosion or erosion-resistant overlays, and the economic advantages of high deposition rates become decisive.
Process Principles and Configuration
Strip electrode cladding operates on the principle of arc heating between a strip electrode and a consumable rod electrode, with the molten strip metal being deposited onto the substrate to form the overlay layer. Unlike conventional MIG or SAW processes, strip electrode cladding achieves exceptionally high deposition rates (typically 5–15 kg/h, compared to 1–3 kg/h for MIG) because the entire cross-section of the strip is melted and transferred in a single pass. The process is typically performed with the strip electrode positioned at a slight angle (5–15°) relative to the substrate surface, with the arc concentrated at the leading edge of the strip.
Process Parameters for Low-Carbon Steel Cladding
| Parameter | Value | Function |
|---|---|---|
| Stripping Current | 200–400 A | Melts the strip electrode |
| Rod Current | 150–300 A | Generates arc and provides shielding |
| Strip Width | 10–25 mm | Determines bead width per pass |
| Strip Thickness | 1.5–3.0 mm | Controls deposition volume |
| Travel Speed | 100–300 mm/min | Balances quality and productivity |
| Electrode Angle | 10–20° | Optimizes arc stability |
| Gas Shielding | CO₂ or Ar/CO₂ mix | Protects molten pool |
| Preheat Temperature | 100–200°C | Reduces cracking risk |
Technical Challenges and Solutions
The primary challenge in strip electrode cladding of low-carbon steel is achieving consistent metallurgical quality at high deposition rates. Rapid melting and solidification of the strip material can lead to incomplete fusion at the substrate interface, particularly in the first layer. Chen's work from Shanghai Power Plant Auxiliary Machinery Factory addresses this through careful control of the rod electrode current, which generates the primary arc responsible for substrate melting and bonding. The stripping current, applied to the strip itself, serves to melt the ribbon material without excessively penetrating the substrate.
A critical insight from this era of development is the relationship between strip electrode composition and dilution behavior. For corrosion-resistant cladding on low-carbon steel, the dilution from the base metal can be as high as 30–50% in the first layer, which may compromise the corrosion resistance of the overlay. The solution involves either multiple layers (typically 3–5 layers to achieve a dilution of less than 10% in the final surface layer) or the use of highly alloyed strip materials that maintain acceptable properties even at elevated dilution levels.
Defect Analysis and Prevention
| Defect | Cause | Prevention Method |
|---|---|---|
| Lack of fusion | Insufficient rod current, contamination | Increase rod current, clean surface |
| Cracking | High cooling rate, hydrogen | Preheat, use low-hydrogen rod |
| Uneven bead profile | Inconsistent travel speed, angle | Automated feeding, fixed angle |
| Excessive dilution | High heat input, thin strip | Reduce current, use thicker strip |
| Oxidation inclusions | Inadequate shielding | Increase gas flow, proper nozzle position |
Industrial Application Context
In the power plant environment where this technology was developed, strip electrode cladding found extensive application in protecting boiler tubes, turbine casings, pump casings, and heat exchanger components from erosion-corrosion damage. The high productivity of strip electrode cladding (achieving 10–15 kg/h deposition rates) made it economically viable for large-area overlays that would be prohibitively expensive using conventional arc welding methods. For a typical power plant maintenance program, strip electrode cladding could reduce the cost per square meter of overlay by 40–60% compared to multi-pass MIG or SAW cladding.
The technology also offered advantages in repair applications, where rapid restoration of worn or corroded surfaces was critical for minimizing equipment downtime. The ability to apply thick overlay layers (up to 5–10 mm per pass) in a single operation made strip electrode cladding particularly suitable for rebuilding worn surfaces on rotating machinery components such as shafts, impellers, and valve seats.
Study Reflections and Modern Relevance
Although published in 1991, the fundamental principles described in this paper remain directly applicable to modern strip cladding operations. The evolution from manual to automated strip electrode cladding systems has improved consistency and quality, but the core process physics—arc stabilization, dilution control, and multi-layer strategy—remain unchanged. For contemporary engineers working on large-area cladding applications such as storage tanks, reactor internals, or pipeline components, the productivity advantages of strip electrode technology continue to make it a competitive choice, particularly when combined with modern automated wire feeding systems and real-time process monitoring. The paper serves as a valuable historical reference demonstrating how systematic process development in industrial settings can yield practical solutions that endure across decades of technological advancement.