Dual-Wire Submerged Arc Overlay Temperature Field Simulation Using ABAQUS

Literature Overview and Research Background

This study, conducted by Zhou Boyun and colleagues from Shanxi Electric Power Vocational College and Liaoyang Petrochemical Engineering Co., and published in "Welding Technology" (2012, Vol. 41, No. 11, pp. 13-16), presents a finite element analysis (FEA) approach to modeling the temperature field of dual-wire submerged arc hardfacing (DSAH) using ABAQUS software. The research addresses a critical need in overlay welding: predicting how welding parameters influence the thermal history, weld geometry, and ultimately the microstructure and properties of the overlay deposit. The use of dual-wire technology, which doubles the metal deposition rate compared to single-wire SAW, is particularly relevant for large-scale industrial hardfacing applications where productivity is paramount.

Core Technical Findings

Finite Element Modeling Approach

The authors developed a FORTRAN subroutine within ABAQUS to implement a moving heat source model that accurately represents the thermal input of the dual-wire submerged arc welding process. The model accounts for the spatial distribution of heat from both wire positions, the convective and radiative heat losses from the workpiece surface, and the latent heat of fusion during solidification. The thermal analysis was coupled with a moving mesh technique to handle the continuous advancement of the heat source along the weld path.

Parameter Sensitivity Analysis

The simulation results revealed clear trends in how welding parameters influence the thermal field and weld geometry:

These trends are physically intuitive: higher current and voltage increase the total heat input, expanding the melt pool, while higher travel speed reduces the time available for heat diffusion, resulting in a narrower and shallower weld. The consistency between simulation predictions and experimental validation confirms the reliability of the FEA model.

Dual-Wire Configuration Effects

The dual-wire configuration introduces additional complexity compared to single-wire SAW, as the interaction between the two heat sources affects the thermal field in a non-linear manner. The spacing between the two wires, their relative positions, and the synchronization of their travel all influence the resulting temperature distribution. The FEA model enables systematic evaluation of these geometric parameters without the expense and time of physical experiments.

Engineering Practice Implications

Process Development and Optimization

The FEA approach described in this study provides a powerful tool for process development and optimization. Engineers can use the validated model to predict the effects of parameter changes before committing to physical trials, significantly reducing development time and cost. For overlay welding applications, where the thermal history directly determines the microstructure and properties of the deposit, this predictive capability is invaluable.

Application to Pipeline Overlay Welding

In pipeline hardfacing, where overlays are often applied to large-diameter pipes and fittings, the dual-wire SAW process offers a significant productivity advantage over manual or single-wire methods. The FEA model can be used to optimize the dual-wire parameters for specific pipe geometries, ensuring adequate penetration into the base material while maintaining a controlled dilution rate. For large-diameter pipe repair, the model can also predict the thermal distortion and residual stress distribution, enabling the design of effective preheating and post-weld treatment strategies.

Model Validation and Limitations

The study's experimental validation confirms the model's predictive accuracy for weld width and penetration. However, engineers should be aware of several limitations:

1. Material properties: The model assumes constant or linearly temperature-dependent material properties, which may not accurately represent the complex behavior of high-alloy overlay materials during solidification.
2. Phase transformation: The model does not account for solid-state phase transformations (e.g., martensitic transformation) that occur during cooling, which significantly affect the final microstructure and residual stress.
3. Multi-pass effects: The model focuses on a single pass, whereas actual overlay builds often require multiple passes with complex thermal histories.
4. Dilution prediction: The model predicts heat input but does not directly model the dilution of base material into the overlay, which is critical for controlling overlay composition.

Process Window Definition

Based on the simulation and experimental results, engineers can define a practical process window for dual-wire submerged arc hardfacing:

Study Insights and Reflections

The most significant value of this study lies in its demonstration that FEA can serve as a reliable and cost-effective tool for overlay welding process development. The validated model provides a quantitative understanding of parameter effects that would be difficult to obtain through experimentation alone. For engineers working in pipeline and equipment hardfacing, the ability to predict weld geometry and thermal history before welding enables more informed process decisions and reduces the risk of defects. The consistency between simulation and experimental results builds confidence in the model's applicability to real-world production scenarios. However, the study also highlights the importance of model validation, as even well-constructed FEA models can produce misleading results if their assumptions are not verified against physical reality. The dual-wire configuration adds complexity but also offers the productivity advantages necessary for large-scale industrial applications, making the FEA approach particularly valuable for optimizing this advanced welding process.