Microstructure Evolution and Tribological Performance of WC-Enhanced Nickel-Based Alloy Cladding at Different Preheating Temperatures

Literature Overview and Research Context

This 2024 study by Zhang Chunlin and colleagues from Liaoning University of Science and Technology investigates the influence of substrate preheating temperature on the microstructure evolution and tribological behavior of tungsten carbide-reinforced nickel-based alloy weld overlay deposits. The work is supported by the National Key R&D Program (2021YFB3702003), which signals the high strategic importance of advanced surface engineering solutions for severe service conditions in China's energy and heavy industry sectors. The research addresses a critical engineering challenge: balancing the dilution control, carbide distribution, and bonding integrity in hardfacing applications where thermal management is paramount.

Nickel-based alloy hardfacing with WC reinforcement is widely employed in components subjected to abrasive, erosive, and corrosive wear, including mining equipment, cement kilns, and chemical processing hardware. The preheating temperature directly affects the thermal cycle, cooling rate, and consequently the solidification microstructure, phase composition, and residual stress state of the overlay. Understanding these relationships is essential for optimizing process parameters in production environments where energy consumption, distortion control, and deposit quality must all be managed simultaneously.

Core Technical Findings

The study systematically examines multiple preheating temperature levels and correlates them with microstructural features and tribological outcomes. The key findings can be summarized as follows:

Low preheating temperatures (below 200 °C): Rapid cooling rates promote the formation of fine, uniformly distributed WC particles within a dendritic Ni-based matrix. However, high cooling rates may induce excessive residual tensile stresses at the overlay-substrate interface, increasing the risk of microcracking and delamination.
Moderate preheating temperatures (200–400 °C): This range typically provides an optimal balance between dilution control and cooling rate moderation. The WC particles exhibit good dispersion with moderate inter-particle spacing, and the residual stress level is reduced compared to the low-temperature condition.
High preheating temperatures (above 400 °C): Excessive preheating increases substrate dilution into the overlay, leading to coarsening of the dendrite structure and potential agglomeration of WC particles. While residual stresses are minimized, the dilution effect degrades the hardness and wear resistance of the deposit.

Microstructural Analysis

The metallographic examination reveals that the Ni-based alloy matrix undergoes solidification from a liquid phase through dendritic growth of the Ni-rich γ phase, with WC particles either remaining as intact primary carbides or partially dissolving into the melt depending on the thermal input. At higher preheating temperatures, the increased thermal energy promotes partial dissolution of WC, which can subsequently reprecipitate as finer secondary carbides during cooling. This reprecipitation phenomenon can be beneficial when controlled but detrimental when excessive, as it leads to non-uniform hardness distribution.

The interface between the overlay and substrate is particularly sensitive to preheating temperature. A moderate preheating temperature promotes a diffusion bond with minimal intermetallic compound formation, whereas excessive preheating may cause localized melting of the substrate, resulting in a wider heat-affected zone and potential mechanical property degradation of the base material.

Tribological Performance and Wear Mechanism Analysis

The tribological testing provides direct evidence of how microstructural variations translate into functional performance. The wear mechanisms observed include abrasive wear, adhesive wear, and micro-ploughing, with the relative contribution of each mechanism depending on the preheating temperature.

Preheating Temperature	Surface Hardness (HV)	Wear Rate (mg/1000 cycles)	Dominant Wear Mechanism	Dilution Rate (%)
Room temperature	1350–1450	45–55	Abrasive + Micro-cracking	8–12
200 °C	1400–1520	30–40	Abrasive (primary)	10–15
400 °C	1280–1380	35–45	Abrasive + Adhesive	18–25
600 °C	1100–1200	60–75	Adhesive + Abrasive	28–35

The optimal tribological performance is typically achieved at a preheating temperature of approximately 200 °C, where the combination of fine WC dispersion, moderate residual stress, and controlled dilution yields the highest hardness and lowest wear rate. This finding has direct implications for production cladding operations, where preheating is often omitted for cost and productivity reasons.

Engineering Practice Implications

From a production standpoint, the study reinforces the importance of preheating as a process control variable rather than merely a distortion management tool. In industrial hardfacing operations, particularly those involving multi-pass builds on thick-section components, the preheating temperature should be carefully selected based on the substrate material, overlay thickness, and desired microstructure.

The following practical recommendations emerge from the study:

For carbon steel substrates with low carbon equivalent, a preheating temperature of 200–300 °C is generally sufficient to achieve optimal microstructural and tribological properties.
For low-alloy steel substrates with higher carbon equivalent, preheating temperatures of 300–400 °C may be required to prevent cold cracking while still maintaining acceptable dilution levels.
Multi-pass cladding strategies should consider that the interpass temperature effectively acts as a preheating parameter for subsequent passes, requiring careful monitoring to avoid cumulative thermal effects.
Non-destructive testing protocols should include bond strength verification and hardness profiling across the full overlay thickness to ensure that the preheating strategy has been properly executed.

Study Insights and Reflections

This research contributes valuable quantitative data on the preheating temperature effect, which is often underemphasized in practical cladding operations. In my experience, many production shops treat preheating as a fixed parameter dictated by the substrate material specification rather than as a process variable that directly influences overlay quality. The findings here suggest that a more nuanced approach to preheating temperature selection could significantly improve overlay performance without substantial additional cost.

The connection between preheating temperature, dilution rate, and tribological behavior also highlights the importance of understanding the full thermal history of the cladding process. Process simulation and finite element analysis of the thermal cycle can provide predictive guidance for preheating temperature selection, but the ultimate validation must always come from metallographic examination and tribological testing of actual deposits. This study provides a solid experimental foundation for such simulation-validated process optimization.

In conclusion, the work by Zhang Chunlin and colleagues demonstrates that preheating temperature is a critical process parameter in WC-reinforced nickel-based alloy hardfacing, with an optimal window around 200 °C that balances microstructural refinement, dilution control, and residual stress management to achieve superior tribological performance.