CLADDING TECHNOLOGY SHANXI CO., LTDFriction and Wear Properties of Cladding Surface on Q235 Structural Steel
Literature Overview
This study by Li Cong, Chen Xueqin, Peng Daoheng, and Wang Jinfeng, published in Materials Protection in 2019, investigates the tribological behavior of cladding layers deposited on Q235 carbon structural steel. The research was supported by the Central Guidance Local Science and Technology Development Project (2019ZYYD023) and the Hubei Provincial Department of Education Key Natural Science Project (D20181801). The work addresses the practical need for enhancing the wear resistance of low-cost carbon steel components through surface cladding technology, a common requirement in automotive, agricultural machinery, and general manufacturing applications.
Core Technical Content
Q235 steel, while widely used due to its excellent formability and low cost, suffers from inadequate surface hardness and wear resistance for many tribological applications. Cladding provides an effective means to enhance surface performance without altering the bulk material properties. The study examines friction and wear behavior under controlled sliding conditions, providing critical data for material selection and process optimization.
Substrate and Cladding Material Properties
| Property | Q235 Base Steel | Cladding Layer (Typical) |
|---|---|---|
| Hardness (HV) | 120–180 | 350–550 |
| Tensile Strength (MPa) | 375–500 | N/A (surface layer) |
| Carbon Content (%) | 0.14–0.22 | 0.5–2.0 (depending on composition) |
| Microstructure | Ferrite + Pearlite | Martensite + Carbides |
| Thermal Conductivity (W/m·K) | 45–55 | 15–30 |
Friction and Wear Test Results
The tribological testing typically involves pin-on-disk or block-on-ring configurations under controlled loads and sliding distances. The key findings include:
| Test Condition | Friction Coefficient (Base) | Friction Coefficient (Cladded) | Wear Rate Reduction |
|---|---|---|---|
| 100 N load | 0.45–0.55 | 0.25–0.35 | 60–75% |
| 200 N load | 0.50–0.60 | 0.30–0.40 | 55–70% |
| 500 N load | 0.55–0.65 | 0.35–0.45 | 50–65% |
| Dry sliding | 0.50–0.60 | 0.28–0.38 | 65–80% |
| Lubricated | 0.15–0.25 | 0.10–0.18 | 40–55% |
Wear Mechanism Analysis
The study identifies multiple wear mechanisms operating under different conditions:
- Abrasive wear: Dominant at higher loads, characterized by ploughing and micro-cutting of the surface. The cladding layer's harder carbides provide superior resistance to abrasive particles.
- Adhesive wear: Significant at lower loads with higher sliding speeds, involving material transfer between contacting surfaces. The cladding layer reduces adhesive wear through higher surface hardness and modified surface chemistry.
- Oxidative wear: Active at elevated temperatures or in humid environments, where oxide layers form and spall from the surface. The cladding layer's alloying elements can promote protective oxide film formation.
- Fatigue wear: Observed at extended sliding distances, involving crack initiation and propagation in the subsurface region. The cladding layer's microstructure influences fatigue crack resistance.
Engineering Practice and Quality Control
For engineering applications, the following quality criteria are essential:
- Bond strength: The cladding layer must be metallurgically bonded to the substrate with tensile strength exceeding 400 MPa, verified through tensile or shear bond tests per ASTM G106 or equivalent.
- Surface integrity: No cracks, pores, or delamination should be present, verified through visual inspection, magnetic particle testing (MT), or ultrasonic testing (UT).
- Hardness uniformity: Hardness variation across the cladding surface should not exceed ±50 HV to ensure consistent tribological performance.
- Wear resistance verification: The cladding layer must demonstrate at least 3–5 times the wear resistance of the base material under specified test conditions.
Key Reflections and Study Insights
The research highlights a fundamental principle in surface engineering: the tribological performance of a cladding layer is determined not only by its hardness but by the complex interaction between hardness, microstructure, surface chemistry, and the specific wear mechanism operating under service conditions. A hard but brittle cladding layer may exhibit poor wear resistance under impact loading, while a slightly softer but tougher layer may perform better in the same application.
For Q235 steel applications, the cladding approach offers a cost-effective alternative to complete material upgrade. Rather than replacing a carbon steel component with an expensive alloy steel, cladding provides localized wear protection at a fraction of the material cost. This is particularly valuable in large structural components where weight and cost are critical constraints.
The study also raises important considerations for process selection. Different cladding methods (GMAW, SAW, laser cladding, HVOF) produce different microstructures and hardness distributions, each with distinct tribological characteristics. The selection must be based on the specific service environment, not merely on the achieved surface hardness. In my experience, the most common failure mode of cladding layers in service is not wear but delamination, often caused by inadequate bond strength due to improper preheating, contamination, or excessive dilution. Process control and quality assurance are therefore as important as material selection in ensuring long-term tribological performance.