Zhuojin Pipe Fitting Co., LtdANSYS-Based Dynamic Simulation of Temperature Field in Dissimilar Material Overlay Welding
Literature Overview
The paper by Dong Xiaoqiang and Duan Hongyan from the School of Materials Science and Engineering at Shenyang University of Technology, published in the Journal of Shenyang University of Technology (Vol. 30, No. 5, 2008, pp. 551-554), presents a finite element simulation approach for the temperature field during overlay welding of dissimilar materials. The authors recognized that most existing numerical simulations of overlay welding temperature fields were limited to homogeneous (same-material) conditions, and they developed a methodology using ANSYS software with APDL programming to model the transient temperature evolution during dissimilar material overlay welding. The simulation employed a three-dimensional finite element mesh with adaptive mesh refinement for the weld metal region and a moving heat source model.
Numerical Methodology and Model Development
The key technical contribution of this work is the development of a computationally efficient approach for simulating the temperature field in dissimilar material overlay welding. The methodology involves several critical components:
| Component | Description |
|---|---|
| Software | ANSYS with APDL programming |
| Mesh technique | 3D finite element mesh with adaptive refinement |
| Heat source model | Moving Gaussian or double-ellipsoidal heat source |
| Material model | Dissimilar materials with distinct thermal properties |
| Boundary conditions | Convective and radiative heat loss at surfaces |
| Validation | Comparison with experimental thermocouple measurements |
The use of adaptive mesh refinement is particularly important for computational efficiency. In overlay welding, the weld pool region experiences extreme temperature gradients and rapid thermal transients, requiring a fine mesh for accurate resolution. However, refining the entire model mesh would lead to prohibitively large computational costs. The adaptive technique dynamically refines the mesh in the weld metal region as the heat source moves, generating new elements ahead of the arc and coarsening elements behind it. This approach maintains accuracy where it is needed while keeping the overall mesh size manageable.
The APDL programming allows the user to automate the heat source movement, control the mesh adaptation, and manage the transient analysis in a systematic manner. The moving heat source is implemented as a surface heat flux applied to the top surface of the model, with the flux distribution following a Gaussian or double-ellipsoidal profile to represent the energy density of the welding arc.
Validation and Engineering Applicability
The authors validated their simulation results by comparing the computed temperature profiles with experimental thermocouple measurements taken during actual dissimilar material overlay welding trials. The close agreement between simulated and measured temperatures confirms the accuracy of the numerical model and the appropriateness of the heat source parameters and boundary conditions. This validation is essential for establishing confidence in the simulation as a predictive tool for welding process design and optimization.
From an engineering practice perspective, the ability to simulate the temperature field in dissimilar material overlay welding has several important applications. First, it allows engineers to predict the heat-affected zone width and depth, which is critical for assessing the risk of cracking and distortion. Second, it enables the optimization of welding parameters such as heat input, travel speed, and interpass temperature to achieve desired microstructural outcomes. Third, it facilitates the design of preheat and post-weld heat treatment procedures to control residual stresses and minimize distortion.
The study's emphasis on dissimilar material conditions is particularly relevant for overlay welding applications where a wear-resistant or corrosion-resistant alloy is deposited on a structural steel base. The thermal property mismatch between the two materials creates complex temperature gradients that can lead to thermal stresses and cracking if not properly managed. The simulation approach developed in this paper provides a tool for evaluating these risks before physical trials are conducted.
Key Reflections and Implications
The work by Dong and Duan represents an important step in the application of numerical simulation to overlay welding process engineering. The development of an efficient and validated methodology for dissimilar material conditions addresses a significant gap in the existing literature. For practitioners in steel pipe and pipe fitting manufacturing, this type of simulation capability can be leveraged to optimize overlay welding procedures for pipeline repair, corrosion protection, and wear-resistant surfacing. The key challenge remains the accurate modeling of material properties at elevated temperatures, which requires reliable thermophysical data for both the base and overlay materials. Future work should incorporate coupled thermal-mechanical analysis to predict residual stresses and deformation, as well as microstructural modeling to predict phase transformations and property evolution in the weld and HAZ.