Finite Element Stress Analysis of Flat Plate Surfacing Solidification Based on ANSYS

Literature Overview

This paper by Hao Zilong and Shi Guanglin from Guilin University of Technology, published in Journal of Guilin University of Technology (2016, Vol. 27, No. 1), presents a three-dimensional finite element analysis of the temperature field and stress field during flat plate surfacing of 25 steel. The study uses ANSYS with a Gaussian distributed surface heat source model and APDL programming for heat source movement simulation. The research is supported by a Guangxi scientific research and technology development program project. The primary objective is to understand the residual stress distribution and its relationship to process parameters, providing a basis for optimizing welding parameters to reduce cracking tendency.

Core Technical Points

The finite element model employs a Gaussian function distribution surface heat source, which is a widely used approximation for arc welding heat input. The APDL (ANSYS Programming Language for DYNamics) functionality enables the simulation of heat source movement along the weld path, allowing for dynamic analysis of the temperature and stress fields as the weld progresses. The computational results reveal that the maximum longitudinal stress is distributed in the weld zone, while the maximum transverse stress is located at the fusion line.

The analysis further demonstrates that reducing welding current or increasing welding speed both improve the hot cracking resistance of the surfacing deposit. This finding is consistent with the general understanding that lower heat input reduces the temperature gradient and the associated tensile stresses in the solidification zone, thereby decreasing the driving force for crack formation. However, the paper does not explicitly quantify the threshold values beyond which cracking becomes unacceptable, which would be valuable for practical parameter selection.

Process Analysis and Engineering Implications

The use of finite element analysis for surfacing process optimization represents a powerful approach that can complement experimental trials. By simulating the thermal and mechanical behavior of the weld, engineers can predict stress distributions and identify potential cracking locations before conducting physical trials. This is particularly valuable for surfacing applications where the deposited layer is thin and the process parameters have a significant influence on the thermal history.

The Gaussian heat source model, while widely used, has limitations in accurately representing the complex heat input distribution of surfacing processes. Surfacing involves a continuous deposition of material, and the heat source geometry may differ from that of a conventional arc weld. Engineers should be aware that the simulation results provide qualitative trends and relative comparisons rather than absolute quantitative predictions. The model should be validated against experimental measurements before being used for definitive process parameter selection.

Key Questions and Reflections

The paper focuses on 25 steel, a low-carbon steel with relatively low cracking susceptibility. The findings may not directly translate to higher-carbon or alloy steels, where the cracking resistance is more sensitive to process parameters. The paper also does not discuss the effect of surfacing layer thickness, which is a critical parameter in surfacing applications. Thicker deposits experience different thermal histories and stress states compared to thin single-pass deposits, and the cracking behavior may differ significantly. Engineers should consider extending the finite element analysis to include multi-pass surfacing simulations and a wider range of base materials.

Study Insights and Implications

This paper demonstrates the value of finite element analysis as a tool for understanding and optimizing surfacing processes. The identification of stress concentration locations and the correlation between process parameters and cracking tendency provide actionable insights for engineers seeking to improve surfacing quality. The approach of using APDL for dynamic heat source modeling is a practical technique that can be adapted to various surfacing configurations. For engineers in the field of surfacing and overlay welding, this paper highlights the importance of combining numerical simulation with experimental validation to develop robust process windows that minimize cracking and ensure reliable deposit quality.