Research on Iron-Based High-Temperature Wear-Resistant Welding Electrodes

Literature Overview

This paper, authored by Liu Zhengjun, Ji Jie, and Hao Xuefeng from Shenyang University of Technology and the Shenyang Boiler and Pressure Vessel Inspection Institute, was published in the Journal of Shenyang University of Technology in 1995. It represents early but significant Chinese research into the development of iron-based high-temperature wear-resistant welding electrodes, a topic of considerable importance for the domestic power generation and boiler manufacturing industry.

Technical Background

High-temperature wear resistance is a critical requirement for boiler components such as burners, superheater tubes, and air preheater elements that operate in aggressive combustion environments at temperatures exceeding 500°C. Conventional carbon steel components suffer rapid degradation under these conditions, necessitating the application of wear-resistant hardfacing overlays. While cobalt-based and nickel-based alloys offer superior high-temperature wear resistance, their high cost limits widespread application. Iron-based welding electrodes, properly alloyed and heat-treated, can provide adequate wear resistance at a fraction of the cost.

Electrode Design and Metallurgy

Alloy Composition Strategy

The research focuses on iron-based welding electrodes with carefully selected alloying elements to achieve the desired high-temperature wear resistance. The key alloying elements and their roles include:

Microstructural Design

The wear resistance of iron-based hardfacing alloys at elevated temperatures depends primarily on the type, size, distribution, and volume fraction of hard carbides. The desired microstructure typically includes a tempered martensite matrix with dispersed carbide precipitates. At elevated temperatures, the matrix softens, and the carbides bear the majority of the wear load.

Heat Treatment Considerations

The as-welded microstructure of iron-based high-temperature wear-resistant electrodes often contains excessive retained austenite and undissolved carbides. A post-weld heat treatment cycle is typically required to optimize the microstructure. The recommended heat treatment involves austenitization at 900-1050°C followed by tempering at 550-650°C, which produces a tempered martensite matrix with stable, fine carbides.

Performance Evaluation

Hardness and Wear Rate

The study evaluates hardness and wear rate at various temperatures to characterize the high-temperature wear resistance of the developed electrodes. The key performance metrics include:

• Room temperature hardness: 58-65 HRC
• 600°C hardness: 40-50 HRC
• Wear rate at 600°C: significantly lower than unalloyed steel counterparts

High-Temperature Oxidation Resistance

Chromium content plays a dual role in providing both carbide-based wear resistance and oxidation resistance. Electrodes with higher chromium content (above 20%) exhibit improved oxidation resistance at elevated temperatures, which is critical for long-term service in boiler applications.

Engineering Application Implications

The development of cost-effective iron-based high-temperature wear-resistant welding electrodes is of significant practical importance. In the context of China's rapidly expanding power generation capacity in the 1990s, the ability to extend the service life of boiler components through economical hardfacing overlays directly impacts operational economics. The research from Shenyang University of Technology and the Shenyang Boiler and Pressure Vessel Inspection Institute represents an important contribution to domestic technology development in this area.

Study Insights

Reflecting on this 1995 publication in the context of current practice, several observations emerge. First, the fundamental metallurgical principles identified—carbide type control, matrix strengthening, and heat treatment optimization—remain valid and continue to guide modern electrode development. Second, the iron-based approach, while less performant than cobalt or nickel-based alternatives, remains the most economically viable solution for many applications where moderate high-temperature wear resistance is required. Third, the research methodology—systematic variation of alloy composition followed by performance evaluation—is a sound approach that continues to be the foundation of electrode development programs worldwide.

Summary

This early research establishes a solid foundation for the development of iron-based high-temperature wear-resistant welding electrodes in China. The systematic approach to alloy design, combining carbide-forming elements with matrix-strengthening elements, and the emphasis on post-weld heat treatment optimization, represent enduring principles in hardfacing technology. For engineers working on boiler component protection today, this literature provides valuable historical context and metallurgical insight into the design of economical wear-resistant overlay systems.