Zhuojin Pipe Fitting Co., LtdMicrostructure and Sliding Friction Wear Properties of High-Chromium Bimetallic Wear-Resistant Plate Overlay Layer
Literature Overview
This paper by Liu Tianjun, Li Xintong, and Wang Qingliang from Hebei Iron and Steel Group Mining Co., Ltd. and China University of Mining and Technology, published in Materials and Design (Volume 50, Issue 5, 2026, pages 79-85), investigates the microstructure, hardness gradient, and sliding friction wear behavior of high-chromium bimetallic wear-resistant plate overlay layers. The research was funded by the Central University Basic Scientific Research Business Special Fund Project (2019XKQYMS38). This study is directly applicable to engineers designing wear-resistant linings for mining equipment, ore processing plants, and bulk material handling systems.
Core Technical Findings
The study examines overlay layers on high-chromium bimetallic wear-resistant plates under two load conditions (200 N and 600 N) and two environmental conditions (dry friction and quartz sand friction). The overlay layer composition and performance are compared with conventional martensitic wear-resistant steel.
Microstructural Characteristics
| Feature | Description |
|---|---|
| Primary carbide | Cr₇C₃ (hexagonal, high hardness ~2000 HV) |
| Matrix phase | α-Fe (ferritic matrix) |
| Secondary carbide | Small amount of Cr₂₃C₆ |
| Hardness gradient | Increases from base steel toward overlay layer (gradient transition at fusion zone) |
| Carbide morphology | Cr₇C₃ forms interconnected network; Cr₂₃C₆ appears as isolated particles |
Wear Performance Comparison
| Test Condition | Metric | High-Cr Overlay Layer | Martensitic Wear-Resistant Steel | Relative Performance |
|---|---|---|---|---|
| Dry friction, 200 N | Friction coefficient | ~0.4-0.5 | ~0.4-0.5 | Comparable |
| Dry friction, 200 N | Mass loss | Lower | Higher | Superior |
| Dry friction, 200 N | Volumetric wear rate | Lower | Higher | Superior |
| Dry friction, 600 N | Mass loss | Lower | Higher | Superior |
| Quartz sand, 200 N | Mass loss | Lower | Higher | Superior |
| Quartz sand, 600 N | Mass loss | Lower | Higher | Superior |
| Quartz sand, 600 N | Volumetric wear rate | Lower | Higher | Superior |
Wear Mechanism Analysis
The study identifies distinct wear mechanisms under different conditions:
Dry friction environment:
- Primary mechanism: Abrasive wear through asperity cutting
- Secondary mechanism: Fatigue spalling
- Surface features: Parallel grooves following sliding direction; shallow subsurface cracks leading to flake detachment
Quartz sand environment:
- Primary mechanism: Abrasive wear through combined asperity cutting and hard quartz particle micro-cutting
- Secondary mechanism: Fatigue spalling
- Surface features: Deeper, more irregular grooves; embedded quartz particles causing localized subsurface damage; increased micro-crack density
The transition from asperity-only cutting in dry friction to combined asperity-quartz cutting in sand environment explains the increased wear rate under sand conditions, despite the overlay layer still outperforming martensitic steel.
Engineering Practice Implications
Application Selection Criteria
| Application Scenario | Recommended Material | Rationale |
|---|---|---|
| Sliding contact, no abrasive particles | High-Cr overlay or martensitic steel (comparable) | Friction coefficient is similar; cost determines selection |
| Sliding contact with fine abrasive particles | High-Cr overlay layer | Superior resistance to micro-abrasion from hard particles |
| Heavy load sliding (>500 N equivalent) | High-Cr overlay layer | Maintains lower wear rate under elevated loads |
| Impact-abrasion combined service | Evaluate separately | This study does not address impact loading |
Design and Manufacturing Considerations
For engineers specifying high-chromium bimetallic wear-resistant plates:
- Carbide morphology control: The Cr₇C₃ network provides excellent wear resistance but may compromise toughness. For applications requiring impact resistance, consider compositions that favor dispersed Cr₇C₃ particles over interconnected networks.
- Hardness gradient utilization: The gradient from base steel to overlay layer provides a natural stress transition zone, reducing the risk of delamination under thermal cycling or mechanical shock.
- Thickness optimization: The effective wear-resistant zone is typically the top 1-2 mm of the overlay layer. Excessive thickness increases cost without proportional benefit for pure sliding wear applications.
- Surface preparation: The overlay layer surface should be finished to minimize initial asperity height, reducing the contribution of asperity cutting to the overall wear rate.
Study Insights and Independent Reflection
The key engineering insight from this study is that high-chromium overlay layers maintain their wear advantage across a range of loads and environmental conditions, including the presence of hard abrasive particles. This robustness is attributed to the fundamental microstructural difference: the Cr₇C₃ carbide network in the high-chromium overlay provides a continuous hard phase that resists both asperity penetration and abrasive particle cutting, whereas martensitic steel relies primarily on matrix hardness for wear resistance.
I find particularly interesting the finding that friction coefficients are comparable between the two materials despite significant differences in wear rate. This indicates that the wear mechanism is dominated by material removal rather than frictional energy dissipation. For engineers selecting materials for applications where friction coefficient is critical (such as conveyor systems or braking applications), this finding suggests that the high-chromium overlay layer can provide superior wear life without compromising frictional characteristics.
The study's focus on sliding wear is appropriate for the mining industry context of the authors' affiliation, but I would caution that real-world mining applications often involve combined wear modes including impact, erosion, and corrosion-abrasion synergy. The high-chromium overlay layer's performance under these combined conditions may differ from the pure sliding wear results presented here. Engineers should conduct application-specific wear testing or consult long-term field performance data before making material selections for critical service.
Concluding Summary
This study provides valuable comparative data on the sliding wear performance of high-chromium bimetallic overlay layers versus conventional martensitic wear-resistant steel. The overlay layer demonstrates superior wear resistance across tested conditions while maintaining comparable friction characteristics, making it a compelling choice for sliding-wear-dominated applications in mining and material handling. The Cr₇C₃ carbide network and hardness gradient structure are the key microstructural features responsible for this performance advantage. Engineers should leverage these findings in material selection while recognizing the limitations of laboratory sliding wear tests for predicting real-world multi-mode wear behavior.