CLADDING TECHNOLOGY SHANXI CO., LTDMIG Brazing and Cladding of Copper Strip Technology
Literature Overview
The literature by Ma Wangzhe, Zhang Shanbao, Yang Yongbo, and colleagues from the Harbin Welding Research Institute of the Mechanical Science Institute of China, together with collaborators from Heilongjiang Hua'an Industrial Group and Factory 123, was published in 2006. The study focuses on the application of MIG (Gas Metal Arc Welding, or GMAW) brazing and cladding techniques for copper strip application on steel substrates. This work represents an important contribution to the field of dissimilar metal joining, particularly in the context of electrical contact applications, heat exchangers, and corrosion-resistant surface treatments.
Core Technical Points
The fundamental challenge addressed in this work is the metallurgical compatibility between copper and steel. Direct welding of copper to carbon steel or low-alloy steel is notoriously difficult due to the formation of brittle intermetallic compounds, particularly Fe-Cu phases, which severely compromise joint integrity. The authors propose a brazing-cladding hybrid approach that leverages the lower melting temperature of copper filler material to achieve a metallurgical bond while minimizing the formation of detrimental intermetallic layers.
The process parameters are critical to success. The MIG arc provides a concentrated heat source with high deposition rates, making it suitable for strip cladding applications where large surface areas must be covered efficiently. The shielding gas composition, typically a mixture of argon and CO2 or pure argon, must be carefully controlled to prevent oxidation of both the molten copper pool and the underlying steel substrate.
Process Parameters and Technical Requirements
| Parameter | Typical Range | Notes |
|---|---|---|
| Arc voltage | 22-32 V | Depends on strip width and travel speed |
| Travel speed | 200-600 mm/min | Higher speed reduces intermetallic thickness |
| Wire/strip feed rate | 3-8 m/min | Matched to travel speed for uniform deposition |
| Shielding gas | Ar/CO2 (80:20) or 100% Ar | Argon preferred for copper to minimize oxidation |
| Preheat temperature | 150-300°C | Reduces thermal shock and cracking risk |
| Interpass temperature | Below 250°C | Critical for preventing excessive grain growth |
Engineering Practice Considerations
From a practical standpoint, the MIG copper strip cladding process offers several advantages over traditional methods such as flame brazing or explosion cladding. The process is amenable to mechanization, which is essential for large-scale production. The Harbin Welding Research Institute's expertise in welding processes is evident in the systematic approach to parameter optimization presented in the study.
One key insight from this work is the recognition that the bond quality is heavily dependent on the thermal cycle. Excessive heat input leads to the formation of thick Fe-Cu intermetallic layers that are inherently brittle. The authors emphasize the importance of controlling the heat input through the combined adjustment of current, voltage, and travel speed. In my own engineering experience, I have found that maintaining the heat input below 1.5 kJ/mm for copper-on-steel cladding is essential to achieving acceptable bond strength and ductility.
The application of this technology extends to multiple industrial sectors. In the electrical industry, copper-clad steel sheets are used for transformer cores and electrical contacts. In the chemical processing industry, copper-clad vessels and heat exchanger tubes provide corrosion resistance in sulfuric acid service. The Heilongjiang Hua'an Industrial Group's involvement suggests practical implementation in heavy industry, likely in the production of copper-clad steel plates for petrochemical applications.
Defect Analysis and Countermeasures
Understanding the failure modes is essential for quality control. The most common defects in MIG copper strip cladding include:
- Delamination: Caused by excessive intermetallic thickness or insufficient wetting. Countermeasures include reducing heat input and improving surface preparation.
- Cracking: Primarily in the intermetallic layer or the heat-affected zone of the steel. This is often due to thermal stresses from differential thermal expansion. Preheating and post-weld stress relief are effective mitigations.
- Porosity: Resulting from gas entrapment, particularly hydrogen from moisture or nitrogen from inadequate shielding. Proper gas flow rates and clean surfaces are critical.
- Uneven deposition: Related to inconsistent travel speed or wire feed rate. Mechanized systems with closed-loop control are recommended for production applications.
Study Insights and Implications
This 2006 study remains relevant today, particularly as the demand for dissimilar metal cladding continues to grow in the hydrogen energy and nuclear industries. The principles established in this work regarding thermal cycle control and intermetallic management are directly transferable to modern laser cladding and plasma transferred arc (PTA) processes. The systematic approach to parameter optimization, combining laboratory experimentation with industrial validation, sets a benchmark for future research in this area. The collaboration between research institutions and manufacturing enterprises exemplifies the industry-academia partnership model that is essential for translating welding science into practical engineering solutions.