CLADDING TECHNOLOGY SHANXI CO., LTDResearch on the Preparation of Abrasion- and Heat-Resistant Weld Overlay Electrodes
Literature Overview
Published in China Surface Engineering in 2006 by Ma Jianghong, Yu Yueguang, Xue Wentao, and Huang Jingyong from the Beijing Research Institute of Mining and Metallurgy, this study focuses on the development and manufacturing technology of abrasion- and heat-resistant weld overlay electrodes. The research represents an earlier phase of the BRIMM research program, establishing fundamental processing parameters and compositional design principles for high-temperature wear-resistant welding consumables.
Core Technical Content
The study systematically investigates the relationship between electrode composition, manufacturing process parameters, and resulting weld deposit properties. The research encompasses compositional design, melting technology, heat treatment optimization, and comprehensive property evaluation.
Compositional Design Philosophy
The electrode development follows a systematic approach based on the following metallurgical principles:
- High carbon content (2.5-3.5 wt%): Ensures sufficient carbide volume fraction (30-45%) for hardness and wear resistance
- High chromium content (12-20 wt%): Forms stable Cr-carbides and provides corrosion resistance
- Nickel addition (5-12 wt%): Stabilizes austenite, improves hot workability, and enhances thermal fatigue resistance
- Molybdenum addition (2-4 wt%): Increases solid solution strengthening and improves red hardness
- Manganese addition (1-3 wt%): Promotes austenite formation and improves weldability
Manufacturing Process Parameters
| Process Stage | Parameter | Range | Optimization Target |
|---|---|---|---|
| Induction melting | Temperature | 1600-1700°C | Complete melting, minimal oxidation |
| Holding time | 15-25 min | Compositional homogenization | |
| Casting | Mold temperature | 800-900°C | Controlled cooling rate |
| Pouring temperature | 1500-1550°C | Minimum shrinkage porosity | |
| Hot working | Forging ratio | 3:1 to 5:1 | Grain refinement |
| Temperature | 1100-1200°C | Full plasticity | |
| Heat treatment | Solution temperature | 1050-1150°C | Carbide dissolution |
| Cooling method | Air cool / Furnace cool | Microstructure control | |
| Tempering | Temperature | 400-600°C | Residual stress relief |
| Time | 2-4 hours | Property stabilization |
Weld Deposit Properties
| Property | Cast Electrode | Forged Electrode | Heat-Treated Electrode |
|---|---|---|---|
| Hardness (HV) | 680-720 | 720-760 | 750-800 |
| Red hardness at 500°C (HV) | 480-520 | 520-560 | 550-590 |
| Impact toughness (J/cm²) | 8-12 | 12-18 | 15-22 |
| Wear rate at 400°C (mg/1000r) | 25-30 | 18-22 | 14-18 |
| Thermal fatigue life (cycles) | 200-300 | 350-500 | 500-700 |
Welding Performance Characteristics
The electrodes are designed for both manual (SMAW) and mechanized (SAW, FCAW) welding processes. Key welding characteristics include:
- Arc stability: Current density 15-25 A/mm² (electrode cross-section)
- Deposition efficiency: 65-75% (SMAW), 80-85% (SAW)
- Dilution ratio: 15-25% (single pass), 10-15% (multi-pass with backing plate)
- Deposition rate: 1.5-2.5 kg/h (SMAW, 300-400A), 5-8 kg/h (SAW)
- Required layers: 2-4 layers for 2-3 mm final overlay thickness
Engineering Practice Integration
The electrode preparation technology has been applied to the following industrial scenarios:
- Coal-fired boiler components: Air preheater tubes, economizer tubes, and furnace wall tubes experiencing fly ash abrasion at 300-500°C
- Cement industry: Kiln shell wear plates, preheater cyclone internals, and cooler grate bars
- Power generation: Steam turbine exhaust ducts, flue gas ducts, and desulfurization system components
- Mining and quarrying: Crusher jaws, conveyor rollers, and hopper liners
The typical overlay scheme involves:
- Base preparation: Bevel grinding to 60-75° angle, surface cleaning to SA 2.5 level
- Underlay layer: Low-dilution transition layer (if dissimilar base material)
- Overlay layers: 2-3 passes of abrasion-heat-resistant electrode, total thickness 2-3 mm
- Surface finishing: Light grinding or brushing for uniform thickness
Key Technical Insights and Reflections
This study establishes the fundamental relationship between electrode manufacturing quality and final weld deposit performance. The forging step, often overlooked in conventional electrode production, provides significant benefits in terms of grain refinement and inclusion alignment. The subsequent heat treatment cycle (solution treatment + controlled cooling) is critical for optimizing the carbide distribution and matrix microstructure.
A particularly important finding is the influence of electrode manufacturing defects on weld deposit quality. Porosity in the electrode body (>2% volume fraction) directly transfers to the weld deposit, creating stress concentrators that initiate wear and cracking. The hot working and controlled cooling sequence effectively eliminates internal porosity and achieves density >99% of theoretical.
The study also highlights the importance of flux coating formulation in achieving consistent welding performance. The flux must provide adequate arc stability, slag coverage, and deoxidation while not introducing excessive dilution or unwanted alloying elements. Rutile-type fluxes with controlled TiO2 (30-40%) and CaF2 (5-8%) content provide optimal results for these high-alloy electrodes.
Study Implications for Engineering Practice
The research provides a comprehensive framework for developing custom abrasion- and heat-resistant welding consumables tailored to specific service conditions. Engineers should approach electrode selection not as a commodity purchase but as a technical specification exercise, considering operating temperature, wear mechanism, impact loading, and thermal cycling requirements. The manufacturing quality of the electrode itself is as important as its nominal composition in determining final overlay performance.