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

Literature Overview

This 1995 study published in the Journal of Shenyang University of Technology (Vol. 17, No. 3, pp. 35-38) by researchers from Shenyang University of Technology and the Shenyang Boiler and Pressure Vessel Inspection Research Institute addresses the development of iron-based high-temperature wear-resistant overlay welding electrodes. The work investigated two distinct alloy systems: Cr-Ni-B-W-V-Nb and Cr-B-W-Mo-Nb, evaluating their microstructural characteristics and high-temperature wear resistance performance. This research is particularly relevant to engineers working in high-temperature wear applications such as furnace components, kiln parts, and hot-section equipment in power generation and metallurgical industries.

Alloy System Design and Microstructural Analysis

System 1: Cr-Ni-B-W-V-Nb

The first alloy system was designed to produce a microstructure consisting of alloy austenite matrix with skeletal eutectic carbides and granular eutectic carbides. The austenitic matrix provides excellent high-temperature toughness and thermal stability, while the skeletal eutectic carbides form a continuous network that resists deformation and material removal. The granular eutectic carbides provide additional hardness peaks that act as wear-resistant islands within the matrix.

System 2: Cr-B-W-Mo-Nb

The second alloy system produced a microstructure of fine-grained martensite with blocky hard phases and granular hard phases. The fine-grained martensitic matrix offers high hardness and strength at elevated temperatures, while the blocky and granular hard phases (primarily tungsten and chromium carbides) provide the wear-resistant reinforcement. The addition of niobium in both systems serves as a grain refiner and carbide stabilizer, improving the dispersion and stability of the hard phases at service temperatures.

High-Temperature Performance Comparison

Both alloy systems demonstrated significantly higher high-temperature hardness and wear resistance compared to conventional iron-based overlay materials. The Cr-Ni-B-W-V-Nb system offered superior thermal stability due to its austenitic matrix, making it more suitable for applications involving thermal cycling. The Cr-B-W-Mo-Nb system provided excellent room-temperature and moderate-temperature wear resistance with potentially lower material costs.

Engineering Practice Considerations

The selection between these two alloy systems depends on the specific service conditions. For applications involving severe thermal cycling, such as furnace liners and hot gas ducts, the austenitic Cr-Ni-B-W-V-Nb system is preferred due to its superior thermal shock resistance and dimensional stability. For applications where high-temperature wear is the dominant failure mode and thermal cycling is moderate, the martensitic Cr-B-B-W-Mo-Nb system offers an excellent balance of performance and cost.

The electrode design for both systems required careful control of the flux composition to ensure proper arc stability, slag fluidity, and alloy recovery. The welding parameters, including current type, polarity, and travel speed, were optimized to achieve the desired microstructure and avoid common defects such as hot cracking and porosity.

Key Reflections

This research from 1995 remains highly relevant to modern high-temperature wear applications. The fundamental metallurgical principles governing the design of hardfacing alloys have not changed, and the alloy systems developed in this study continue to inform contemporary hardfacing material selection. The dual-alloy approach, offering austenitic and martensitic options for different service conditions, reflects the engineering philosophy of matching material properties to specific failure mechanisms. For engineers specifying overlay materials for high-temperature applications, this paper provides a valuable reference for understanding the microstructural basis of high-temperature wear resistance in iron-based systems.