Microstructure and Wear Resistance of FeCr15B2MnTi Open-Arc Overlay Alloy

Literature Overview and Research Background

This study examines the microstructure and wear resistance of FeCr15B2MnTi alloy produced by open-arc (gas metal arc welding, GMAW) overlay welding. The FeCr15B2MnTi composition is designed for high-temperature wear applications, incorporating chromium for oxidation resistance, boron for carbide strengthening, manganese for hardenability, and titanium for carbide refinement. Open-arc welding is a cost-effective process widely used for overlay applications where extreme precision is not required but deposition rate and productivity are important.

Core Technical Points

Microstructural Characteristics

The FeCr15B2MnTi overlay exhibits a complex microstructure consisting of a martensitic matrix with dispersed carbide phases. The primary carbides include M7C3 (Cr,Fe)7C3, M23C6, and TiC, with the specific distribution dependent on cooling rate and solidification conditions. The martensitic matrix provides high hardness, while the carbides contribute additional wear resistance through their extreme hardness and thermal stability.

The open-arc welding process produces a relatively coarse microstructure compared to plasma or laser processes due to higher heat input and slower cooling rates. The dilution with the substrate affects the final composition and microstructure, typically introducing additional carbon and iron that influence carbide formation and matrix hardness.

Wear Performance Analysis

The FeCr15B2MnTi overlay demonstrates good wear resistance at ambient temperatures, with performance declining at elevated temperatures due to matrix softening and oxidation. The boron and titanium additions help maintain carbide stability at higher temperatures, providing better high-temperature wear performance than conventional Fe-Cr-C alloys.

Process Parameters and Effects

The open-arc welding process parameters significantly influence the overlay microstructure and properties. Higher currents and lower travel speeds increase heat input, promoting grain coarsening and increased dilution. The shielding gas composition (typically Ar or Ar/CO2 mixtures) affects arc stability and oxide inclusion formation. Typical parameters for FeCr15B2MnTi overlay include currents of 200-300 A, voltages of 25-35 V, travel speeds of 150-300 mm/min, and wire feed rates of 5-10 m/min.

Engineering Practice Integration

The FeCr15B2MnTi overlay is commonly applied to components operating in high-temperature abrasive environments, such as furnace components, kiln parts, and hot metal handling equipment. The open-arc welding process is well-suited for field applications and large surface areas where equipment portability and deposition rate are important. Quality assurance should include:

• Hardness testing to verify overlay properties meet specifications
• Metallographic examination of microstructure and carbide distribution
• Dilution analysis to ensure acceptable substrate contamination
• Wear testing under representative service conditions
• Visual inspection for surface defects and undercut

Key Reflections

The study highlights the potential of FeCr15B2MnTi as a cost-effective overlay alloy for high-temperature wear applications. The open-arc welding process, while less precise than plasma or laser methods, offers significant advantages in terms of productivity, cost, and field applicability. The microstructural characteristics and wear performance are strongly influenced by process parameters, emphasizing the need for careful parameter selection and process control.

This literature provides practical guidance for applying FeCr15B2MnTi overlays using open-arc welding, demonstrating that appropriate process control can achieve satisfactory wear resistance and service performance for a wide range of industrial applications involving high-temperature abrasion.