Numerical Simulation of Temperature Field in TIG Additive Manufacturing of 5356 Aluminum Alloy

Literature Overview

This paper published in Ordnance Materials and Science and Engineering (2021, Vol. 44, No. 2) by Zhao Pengkang et al. from Xi'an University of Technology presents a finite element analysis of TIG-based additive manufacturing of 5356 aluminum alloy using Abaqus software with the element birth-and-death technique. Funded by the China Postdoctoral Science Foundation (2017M613172), Shaanxi Provincial Department of Education Natural Science Foundation (17JK0562), and the university's doctoral startup fund, this study systematically examines the effects of interlayer cooling time, additive direction, and substrate preheating on the temperature field evolution. Experimental temperature measurements were conducted to validate the simulation results, providing a reliable computational framework for process optimization.

Core Technical Findings

The simulation reveals several important thermal behavior characteristics:

1. Interlayer cooling time effect: As the interlayer cooling time increases, both the peak and valley temperatures of the surface midpoint temperature cycle curve of the first layer decrease. This indicates that longer cooling intervals reduce thermal accumulation, which can be beneficial for dimensional accuracy but may introduce cold cracks if temperatures drop below the critical threshold for 5356 alloy.
2. Layer accumulation effect: With increasing number of layers, the peak temperature first drops rapidly and then decreases slowly, while the valley temperature first increases rapidly and then rises slowly. This behavior reflects the progressive thermal equilibrium reached as the deposited mass increases and acts as a heat sink.
3. Additive direction effect: Reciprocating (back-and-forth) additive manufacturing effectively mitigates the heat accumulation defect at the arc termination end observed in single-direction (unidirectional) additive deposition, improving surface flatness and geometric accuracy.
4. Preheating effect: Substrate preheating within a reasonable temperature range promotes more uniform temperature distribution, reducing thermal gradients and associated residual stresses.

Process Parameter Comparison

Validation and Engineering Relevance

The validation of simulation results through measured temperature data is a critical strength of this study. For aluminum alloy additive manufacturing, particularly of 5356 (a 5xxx series alloy commonly used in aerospace and automotive applications), the thermal cycle history directly governs microstructural evolution, including precipitate formation, grain growth, and residual stress development. The 5356 alloy is susceptible to hot cracking during solidification, and the temperature field data provides essential input for predicting crack susceptibility.

From a pipeline and pressure equipment manufacturing perspective, TIG additive manufacturing of aluminum alloys opens possibilities for repair and fabrication of lightweight components. The temperature field data can be directly correlated to welding procedure qualification requirements per ASME Section IX and EN ISO 15614-1, where thermal cycle parameters influence post-weld heat treatment requirements.

Key Reflections and Study Insights

The element birth-and-death technique in Abaqus is a well-established approach for simulating sequential deposition processes, but I note that accurate thermal boundary conditions—particularly convection and radiation at the free surfaces of deposited layers—remain challenging to model precisely. The study's validation with measured temperatures provides confidence, but the spatial resolution of experimental thermocouple measurements may not capture the steep thermal gradients at the arc-affected zone boundary.

The finding that reciprocating deposition improves surface quality is practically significant. In additive manufacturing of complex geometries, the choice of deposition strategy (unidirectional vs. reciprocating) should be considered as a process parameter on par with current, voltage, and travel speed. This insight is transferable to other additive welding processes such as laser cladding and wire arc additive manufacturing, where similar heat accumulation phenomena occur.

The preheating recommendation is consistent with conventional welding practice for 5xxx aluminum alloys, where preheat temperatures of 100–150 °C are commonly specified to reduce thermal gradients. However, in additive manufacturing with multiple layers, the effective preheat from previously deposited layers may reduce the need for external substrate preheating after the initial layers, a nuance that merits further investigation.