Zhuojin Pipe Fitting Co., LtdFriction and Wear Properties of Q235 Structural Steel Surfacing Cladding Surface
Literature Overview
This paper by Li Cong, Chen Xueqin, Peng Daoheng, and Wang Jinfeng, published in "Materials Protection" in 2019 (Vol. 52, No. 10, pp. 70-74), examines the friction and wear behavior of a cladding layer deposited on Q235 structural steel using CO2 gas shielded flux-cored wire arc surfacing. The research was funded by the Central Guidance Program for Local Science and Technology Development (2019ZYYD023) and the Hubei Provincial Department of Education Key Natural Science Project (D20181801). The study employed metallographic microscopy, scanning electron microscopy (SEM), and friction-wear testing to characterize the microstructure and tribological performance of the base metal, cladding layer, and interface region.
Core Technical Findings
The interface region microstructure revealed fine acicular martensite with significantly refined grain size. The friction coefficients decreased sequentially from the base metal to the cladding layer to the interface region. SEM analysis of the wear surfaces showed that the base metal exhibited large wear areas with severe plastic deformation and localized "peeling pits." The interface region, having undergone intense elemental diffusion and metallurgical reactions, produced a high volume of hard phases that improved the microstructural wear resistance. The wear "ploughing" marks and plastic deformation in the interface region were substantially reduced compared to the cladding layer.
| Region | Friction Coefficient | Wear Morphology | Hard Phase Content | Plastic Deformation |
|---|---|---|---|---|
| Base Metal (Q235) | Highest | Large wear area, severe plastic deformation, peeling pits | Low | Severe |
| Cladding Layer | Moderate | Moderate ploughing, moderate plastic deformation | Moderate | Moderate |
| Interface Region | Lowest | Reduced ploughing, improved resistance | High (hard phases) | Significantly reduced |
The progressive reduction in friction coefficient from base metal to interface region is attributed to the increasing concentration of hard phases formed through elemental diffusion and metallurgical reactions at the interface. The interface region represents a transition zone where the chemical composition and microstructure are intermediate between the base metal and the cladding layer, but the intense diffusion and reaction processes create a unique microstructure with superior tribological properties.
Process Analysis and Engineering Implications
CO2 gas shielded flux-cored wire arc surfacing is a practical and economical method for applying wear-resistant overlays to large structural steel components. The flux-cored wire delivers alloying elements directly into the molten pool, promoting the formation of hard carbide and oxide phases in the cladding layer. The use of CO2 as a shielding gas is cost-effective and widely available, making this process suitable for field applications and large-scale component repair. The formation of fine acicular martensite in the interface region is a result of the rapid cooling experienced at the boundary between the molten cladding and the cooler base metal, which promotes a high nucleation rate of martensite.
The observation that the interface region exhibits the best wear resistance is of particular significance for engineering design. In many cladding applications, the interface region is where cracking and delamination initiate under cyclic loading. The fact that this region also has the lowest friction coefficient and the highest hard phase content suggests that it is both mechanically strong and tribologically superior. This finding supports the design philosophy of optimizing the interface chemistry and microstructure rather than focusing solely on the cladding layer composition. For Q235 structural steel applications in construction, machinery, and automotive industries, this surfacing approach offers a practical means of extending component life without the need for complete material replacement.
Study Insights and Reflections
This research provides valuable insight into the tribological behavior of cladding systems, with the key finding that the interface region can outperform both the base metal and the cladding layer in terms of wear resistance. This challenges the conventional assumption that the cladding layer alone determines the wear performance of a coated component. The intense elemental diffusion and metallurgical reactions at the interface create a zone of enhanced hardness and refined microstructure that is difficult to replicate by simple cladding composition optimization. For engineers specifying cladding systems, this suggests that interface design should be given equal importance to cladding composition selection. The study also highlights the importance of characterizing the interface region through advanced microscopy techniques, as the microstructural features in this zone are often overlooked in conventional quality control procedures. Further research should explore the effect of cladding thickness, preheating temperature, and interpass temperature on the interface microstructure and wear performance to establish comprehensive process windows for industrial application.