Zhuojin Pipe Fitting Co., LtdAbrasive Wear Behavior of Fe-Cr-C Wear-Resistant Overlay Alloys
Literature Overview
This research by Wang Zhihui et al. from Beijing University of Technology (Welding Journal, 2010, Vol. 31, No. 11, pp. 73-76) investigates the abrasive wear mechanisms of Fe-Cr-C overlay alloys deposited on Q235 steel via submerged arc surfacing. Funded by the Beijing Municipal Education Commission Science and Technology Program (00900054R5004), the study employs the MLS-225 wet rubber wheel abrasive wear tester with wet quartz sand as the abrasive medium.
Wear Mechanism Analysis
The primary contribution of this paper is the detailed identification of wear mechanisms through SEM observation of wear surfaces combined with energy dispersive spectroscopy (EDS) analysis:
| Wear Mechanism | Dominance | Evidence |
|---|---|---|
| Micro-crack induced spalling | Primary mechanism | Spalling craters with Cr-rich composition |
| Ploughing / micro-ploughing | Secondary mechanism | Groove and wrinkle patterns on wear surface |
The Critical Role of Carbide Fracture
The most significant finding is that spalling events are directly caused by carbide fracture. EDS analysis of spalling craters reveals Cr content corresponding to the (Cr,Fe)7C3 carbide composition range, confirming that these craters form when chromium carbide particles fracture under abrasive loading and subsequently detach from the matrix.
This mechanism can be understood through the following sequence:
- Abrasive particles concentrate stress at carbide-matrix interfaces
- Brittle carbide particles fracture under cyclic loading
- Fractured carbide fragments lose support and detach
- Material loss occurs at the carbide-matrix interface
Implications for Overlay Design
The identification of carbide fracture as the primary wear mechanism has direct implications for overlay alloy design:
| Design Parameter | Recommended Approach | Rationale |
|---|---|---|
| Carbide size | Minimize (fine dispersion) | Smaller particles resist fracture |
| Carbide shape | Rounded over angular | Reduced stress concentration |
| Matrix-carbide bond | Maximize interface strength | Prevents detachment |
| Matrix toughness | Adequate ductility required | Absorbs impact energy |
| Carbide volume fraction | Optimize, not maximize | Excessive volume promotes fracture |
Process Parameters for Submerged Arc Surfacing
| Parameter | Typical Range | Effect on Wear Behavior |
|---|---|---|
| Heat input | 1.5-3.0 kJ/mm | Controls carbide size and distribution |
| Travel speed | 200-400 mm/min | Affects cooling rate and grain size |
| Current | 200-400 A | Influences dilution and phase formation |
| Voltage | 25-35 V | Affects arc stability and penetration |
Study Insights and Reflections
This paper provides a critical perspective on a common misconception in overlay design: that harder is always better. The identification of carbide fracture as the dominant wear mechanism reveals that excessively hard, large, or poorly bonded carbide particles can actually accelerate material loss. For engineers specifying overlay alloys for abrasive service, this work underscores the importance of optimizing the entire microstructure—not merely maximizing hardness. The balance between carbide hardness and matrix toughness, combined with proper interface bonding, determines actual wear performance. This insight is particularly relevant for pipe components subjected to slurry flow erosion, where the interplay between carbide fracture and matrix support directly determines component life.