Three-Dimensional Dynamic Simulation of Temperature Field in Submerged Arc Flat Plate Surfacing

Literature Overview and Research Context

The paper by Shi Baoshan and colleagues (2009), published in Welding Technology, presents a finite element analysis (FEA) approach for simulating the temperature field during submerged arc welding (SAW) flat plate surfacing. The study establishes a three-dimensional dynamic thermal model using ANSYS software with APDL programming to capture the moving heat source characteristics of the surfacing process. This work is particularly relevant to engineers involved in surfacing weld design, thermal management, and process optimization, as accurate temperature field prediction is fundamental to understanding weld quality, residual stress, and microstructure evolution.

Core Technical Approach and Model Development

The study employs a sequential coupled thermal-mechanical analysis approach, with the thermal analysis serving as the primary focus. The finite element model incorporates a moving heat source that follows the weld trajectory, simulating the heat input distribution characteristic of submerged arc surfacing. The APDL (ANSYS Programming Language) is used to automate the heat source movement and thermal boundary condition application, enabling efficient computation of the transient temperature field at multiple time steps.

The model captures the dynamic nature of the surfacing process, including the progressive buildup of heat as the arc traverses the plate surface, the thermal interaction between successive surfacing passes, and the heat dissipation into the base plate. The thermal cycle curves at different locations provide critical information about the peak temperature, cooling rate, and time above critical temperatures, all of which directly influence the microstructure and mechanical properties of the surfacing weld deposit.

Validation and Practical Relevance

The simulation results were validated against experimental temperature measurements, showing good agreement between predicted and measured values. This validation is essential for establishing confidence in the model's predictive capability and for demonstrating its applicability to practical surfacing process design. The model can be used to predict thermal conditions at locations that are difficult to instrument experimentally, such as the weld pool center or the heat-affected zone boundary.

For engineering practice, the temperature field simulation provides several valuable applications. First, it enables the prediction of cooling rates at various locations within the surfacing deposit, which is critical for determining the resulting microstructure and hardness distribution. Second, it allows the evaluation of thermal input for different process parameter combinations, facilitating process optimization without extensive trial-and-error testing. Third, it supports the design of preheat and interpass temperature strategies to control residual stress and distortion in large surfacing operations.

Study Insights and Reflections

This study exemplifies the growing role of computational simulation in welding process engineering. The ability to predict temperature fields with reasonable accuracy using finite element analysis provides a powerful tool for process design, quality control, and troubleshooting. However, engineers should be aware of the limitations of thermal simulation, particularly regarding the simplification of heat source geometry, the neglect of phase transformation effects, and the assumption of constant material properties. The accuracy of the simulation depends heavily on the quality of input parameters, including heat input, travel speed, and material thermal properties at elevated temperatures.

Future work should integrate the thermal analysis with mechanical analysis to predict residual stress and distortion, and with metallurgical analysis to predict microstructure and hardness distributions. The development of more sophisticated heat source models, such as the double-ellipsoidal or Gaussian heat source models, would further improve the accuracy of the simulation.

Summary

The study successfully demonstrates that a three-dimensional finite element model with a moving heat source can accurately predict the transient temperature field during submerged arc flat plate surfacing, providing engineers with a valuable tool for process design, thermal management, and quality optimization in surfacing operations.