CLADDING TECHNOLOGY SHANXI CO., LTDMicrostructure and Erosion Wear Resistance of CrMoV Alloy Cladding Layer
Research Overview
This study by Zhao Jianhua, Zhao Zhanxi, Chen Xiaoliang, Lu Xiao, Zhou Xiang, and Ji Xiulin from Hohai University investigates the microstructure and erosion wear resistance of CrMoV alloy cladding layers. Published in Vibration and Shock in 2015 and supported by the Hohai University Student Innovation Training Program (201210294069), this work addresses the erosion-corrosion challenge in hydraulic engineering applications where metal surfaces are subjected to high-velocity water flow containing solid particles.
Core Technical Points
CrMoV Alloy Composition and Properties
CrMoV is a tool steel alloy containing chromium, molybdenum, and vanadium in specific proportions that provide a combination of hardness, toughness, and wear resistance:
| Element | Content (wt%) | Primary Function |
|---|---|---|
| C (Carbon) | 0.9–1.1 | Hardness through carbide formation |
| Cr (Chromium) | 1.5–2.5 | Hardenability, corrosion resistance |
| Mo (Molybdenum) | 0.8–1.2 | Red tempering, secondary hardening |
| V (Vanadium) | 0.15–0.30 | Fine carbides, wear resistance |
| Mn (Manganese) | 0.3–0.6 | Hardenability, solid solution |
| Si (Silicon) | 0.2–0.5 | Deoxidation, strength |
| Fe (Iron) | Balance | Base metal |
Microstructural Features of Cladding Layer
The cladding layer microstructure, as revealed by metallographic examination, consists of:
- Martensitic matrix: The high carbon content and alloy additions promote martensitic transformation during solidification, providing high hardness (HRC 55–62).
- Carbide distribution:
- Primary carbides: Large, irregularly shaped (up to 5–10 μm) formed during solidification; primarily MC (VC, MoC) and M₂₃C₆ (Cr₂₃C₆)
- Secondary carbides: Fine, uniformly distributed (0.1–1 μm) formed during tempering; primarily M₆C (Mo₆C, W₆C) and M₇C₃
- Retention austenite: Small amounts (5–15%) of retained austenite may be present, depending on the cooling rate and alloy composition.
- Interface microstructure: The fusion boundary between the cladding layer and base metal shows a transition zone with mixed microstructure, including partially transformed base metal and diluted cladding material.
Erosion Wear Mechanisms
Erosion wear in hydraulic applications is governed by the interaction of solid particles with the metal surface under fluid flow:
| Erosion Angle | Dominant Mechanism | Material Response |
|---|---|---|
| 0–15° (grazing) | Ploughing, cutting | Ductile materials perform better |
| 15–30° (intermediate) | Ploughing + cutting | Mixed behavior |
| 30–45° (optimal) | Maximum material removal | Most erosive angle for ductile materials |
| 45–70° (intermediate) | Cutting + fracture | Brittle materials may perform better |
| 70–90° (normal impact) | Fracture, spalling | Hard, brittle materials perform better |
The CrMoV cladding layer demonstrates optimal erosion resistance at impact angles of 60–90°, where its high hardness and carbide content provide effective resistance to particle cutting and surface fracture.
Performance Characterization
Hardness and Microstructure Correlation
| Heat Treatment Condition | Hardness (HRC) | Hardness (HV) | Dominant Microstructure |
|---|---|---|---|
| As-deposited (untempered) | 60–65 | 800–950 | Martensite + retained austenite + primary carbides |
| Tempered 500°C | 55–60 | 700–800 | Tempered martensite + secondary carbides |
| Tempered 550°C | 52–57 | 650 |