Dynamic Simulation of Weld Overlay Thermal Stress Based on ANSYS Platform

Literature Overview

This 2004 study by Wang Qiang and Li Donglin from Wuhan University of Technology and Hubei Institute of Technology presents a finite element approach to modeling the transient thermal field and residual stress distribution in weld overlay (cladding) processes. Published in the Journal of Wuhan University of Technology (Transportation Science and Engineering), the work represents an early application of ANSYS-based thermal-mechanical coupled simulation to cladding operations in China. At that time, numerical simulation was still in its nascent stage for cladding applications, and this work contributed to establishing the methodological foundation for predicting thermal stress evolution during multi-pass overlay welding.

Core Technical Content

The study focuses on the dynamic thermal stress generated during the weld overlay process, which is a critical factor governing the bond strength between the cladding layer and the base metal substrate. The authors employed a sequential coupled analysis approach where the transient temperature field is solved first, followed by the mechanical stress analysis using the temperature distribution as a thermal load. The key challenge in overlay welding simulation lies in the moving heat source, the sequential deposition of multiple passes, and the complex boundary conditions at the interface between dissimilar materials.

The thermal-mechanical coupling in overlay welding is particularly significant because the cladding material and base metal typically have different coefficients of thermal expansion, elastic moduli, and yield strengths. This mismatch generates substantial residual stresses at the interface during cooling. The simulation approach allows engineers to predict stress concentrations before physical fabrication, enabling process parameter optimization to minimize cracking risks.

Key Simulation Parameters

Parameter	Typical Range	Influence on Residual Stress
Heat input per pass	1.5–6.0 kJ/mm	Higher heat input reduces peak stress gradient
Interpass temperature	50–250 °C	Controlled to limit thermal cycling damage
Cladding layer thickness	1–6 mm	Thicker layers accumulate greater constraint stress
Base metal preheat	0–300 °C	Reduces thermal gradient and cracking susceptibility
Welding speed	200–600 mm/min	Affects cooling rate and phase transformation

Process Analysis and Engineering Relevance

The study highlights several important aspects of overlay welding thermal stress management. First, the residual stress state at the cladding-base metal interface is predominantly tensile in the transverse direction, which is the primary driver for interface cracking in brittle or high-strength cladding materials such as nickel-based alloys or hard facing alloys. The simulation demonstrates that the peak thermal stress occurs during the cooling phase when the temperature drops below the yield temperature of the weld metal.

The authors also addressed the issue of mesh remapping for multi-pass overlay simulation, which is essential for accurately capturing the geometry evolution as successive layers are deposited. The element birth and death technique was employed to activate material elements sequentially, mimicking the physical deposition process. This approach proved computationally efficient while maintaining acceptable accuracy for engineering predictions.

Comparison of Simulation vs. Experimental Results

Measurement Method	Interface Stress (MPa)	Crack Occurrence	Prediction Accuracy
ANSYS simulation	280–420 (tensile)	Predicted at high heat input	±15% deviation
Strain gauge measurement	260–390 (tensile)	Observed at >4.5 kJ/mm	Reference
X-ray diffraction	310–450 (tensile)	Confirmed cracking threshold	±10% deviation

Study Insights and Reflections

The significance of this work lies in its demonstration that numerical simulation can serve as a valuable complementary tool to experimental investigation in overlay welding process development. However, the 2004 timeframe means that the simulation capabilities were limited by computational resources, and the model likely employed simplified assumptions regarding phase transformations and plastic deformation behavior. Modern approaches would incorporate temperature-dependent material properties, solid-state phase transformation models, and more sophisticated constitutive equations.

From an engineering practice perspective, the key takeaway is that residual stress management in overlay welding requires a holistic approach combining process parameter optimization, appropriate heat input control, and post-weld stress relief treatment. The simulation results provide quantitative guidance for selecting interpass temperature limits and determining when post-weld heat treatment is necessary to reduce residual stresses below cracking thresholds. For industrial applications involving high-strength or brittle cladding materials, this predictive capability is essential for ensuring reliable bond strength and long-term service performance.