Stability analysis of the Cold Metal Transfer (CMT) brazing process for galvanized steel plates with ZnAl4 filler metal

In welding processes, many factors contribute in achieving a required quality of the welds. Those factors are numerous and they may interact with each other, affecting response parameters such as welding penetration and the Heat Affected Zone (HAZ) size. Some factors are more important while the influence of others is negligible.To find an optimum factor combination in order to maximize penetration and minimize the HAZ is not an easy task. This contribution is aimed to evaluate the influence of welding energy (E) versus the influence of current (I) and welding speed (Vw) on the penetration and HAZ volume in the autogenous Tungsten Inert Gas (TIG) welding process. For this purpose, phenomenological and empirical models are proposed. The first considers an in-house Finite Volume numerical model, and the second is based on Response Surface Method. A sensitivity analysis of the empirical model using two strategies is also performed. In addition, to determine the best-operating conditions, a multi-objective optimization problem is proposed and solved. The presented empirical models were found to provide good concordance in terms of coefficient of determination and p-value, indicating its significance. Each model (with one or more independent variables) represents detailed information about the physical process and can be used for optimization. The sensitivity analysis demonstrates that the current affects penetration and HAZ volume much stronger than the welding speed does. Physically, this is due to the fact current has linear (arc coupling) and non-linear (Joule effect and pressure gradient) influence, and the welding speed contributes linearly, modulating the heat conduction. Finally, it was demonstrated a compromise between the penetration and the HAZ volume by addressing multi-objective optimization. In this context, point C (I = 250 A; VW= 24.8 cm/min) of the Pareto curve is the optimal option for operation since it provides a lower relative HAZ volume while keeping the same penetration and higher productivity (welding speed).

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“…A high feeding rate requires a high current. If this is associated with low welding speed, it can result in lower penetration [41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity analysis and multi-objective optimization of tungsten inert gas (TIG) welding based on numerical simulation

Paes

Andrade

Lobato

et al. 2022

Int J Adv Manuf Technol

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“…Therefore, the coefficient of variation can provide a more accurate characterization of electrical signal dispersion. In CMT deposition, the process stability can be characterized using the Vilarinho regularity index (IV SC ) related to the coefficient of variation [33,34], which is calculated as shown in Equation ( 7):…”

Section: Effect Of the Cmt Characteristic Parameters On Process Stabi...mentioning

confidence: 99%

Optimization of CMT Characteristic Parameters for Swing Arc Additive Manufacturing of AZ91 Magnesium Alloy Based on Process Stability Analysis

Zhang

Shen

et al. 2023

Materials

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The droplet transfer behavior and stability of the swing arc additive manufacturing process of AZ91 magnesium alloy based on the cold metal transfer (CMT) technique were studied by analyzing the electrical waveforms and high-speed droplet images as well as the forces on the droplet, and the Vilarinho regularity index for short-circuit transfer (IVSC) based on variation coefficients was used to characterize the stability of the swing arc deposition process. The effect of the CMT characteristic parameters on the process stability was investigated; then, the optimization of the CMT characteristic parameters was realized based on the process stability analysis. The results show that the arc shape changed during the swing arc deposition process; thus, a horizontal component of the arc force was generated, which significantly affected the stability of the droplet transition. The burn phase current I_sc_wait presented a linear function relation with IVSC, while the other three characteristic parameters, i.e., boost phase current I_boost, boost phase duration t_I_boost and short-circuiting current I_sc2, all had a quadratic correlation with IVSC. A relation model of the CMT characteristic parameters and IVSC was established based on the rotatable 3D central composite design; then, the optimization of the CMT characteristic parameters was realized using a multiple-response desirability function approach.

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“…Authors have studied the stability of the electric arc for arc deposition processes and, in this perspective, have applied numerical indicators to quantify it. In the context of short-circuit deposition processes, the Vilarinho index (IVsc) has been applied to study the mechanism of this transfer mode in GMAW [31][32][33][34], in stability analyses of the cold metal transfer (CMT) in brazing processes [35], and in the optimization of its parameters in the WAAM process [36]. However, the use of the IVsc to verify the stability of the arc as a function of introducing defects in the arc deposition processes has not yet been explored.…”

Section: Introductionmentioning

confidence: 99%

Effects of Contaminations on Electric Arc Behavior and Occurrence of Defects in Wire Arc Additive Manufacturing of 316L-Si Stainless Steel

Souto,

Lima,

Castro

et al. 2024

Metals

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Additive Manufacturing is a manufacturing process that consists of obtaining a three-dimensional object from the deposition of material layer by layer, unlike conventional subtractive manufacturing methods. Wire Arc Additive Manufacturing stands out for its high productivity among the Additive Manufacturing technologies for manufacturing metal parts. On the other hand, the excessive heat input promotes increased residual stress levels and the occurrence of defects, such as pores, voids, a lack of fusion, and delamination. These defects result in abnormalities during the process, such as disturbances in electrical responses. Therefore, process monitoring and the detection of defects and failures in manufactured items are of fundamental importance to ensure product quality and certify the high productivity characteristic of this process. Thus, this work aimed to characterize the effects of different contaminations on the electric arc behavior of the Wire Arc Additive Manufacturing process and the occurrence of microscopic defects in thin walls manufactured by this process. To investigate the presence of defects in the metal preforms, experimental conditions were used to promote the appearance of defects, such as the insertion of contaminants. To accomplish the electric arc behavior analysis, voltage and current temporal data were represented through histograms and cyclograms, and the arc stability was assessed based on the Vilarinho index for a short circuit. Effectively, the introduction of contaminants caused electric arc disturbances that led to the appearance of manufacturing defects, such as inclusions and porosities, observed through metallographic characterization. The results confirm that the introduction of contaminations could be identified early in the Wire Arc Additive Manufacturing process through electric arc data analysis.

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Stability analysis of the Cold Metal Transfer (CMT) brazing process for galvanized steel plates with ZnAl4 filler metal

Cited by 18 publications

References 34 publications

Sensitivity analysis and multi-objective optimization of tungsten inert gas (TIG) welding based on numerical simulation

Sensitivity analysis and multi-objective optimization of tungsten inert gas (TIG) welding based on numerical simulation

Optimization of CMT Characteristic Parameters for Swing Arc Additive Manufacturing of AZ91 Magnesium Alloy Based on Process Stability Analysis

Effects of Contaminations on Electric Arc Behavior and Occurrence of Defects in Wire Arc Additive Manufacturing of 316L-Si Stainless Steel

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