Hot cracking investigation during laser welding of high-strength steels with multi-scale modelling approach

Gao, H.; Agarwal, G. S.; Amirthalingam, Murugaiyan; Hermans, M.J.M.

doi:10.1080/13621718.2017.1384884

Cited by 18 publications

(5 citation statements)

References 23 publications

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“…In fact, in the long crack case, SIFs are known to be effective [27]. This linear quantitative relationship between the cracked area and SIFs can be attributed to the dominant brittle nature of solidification cracking, and is in good agreement with the observations [21,22]. Therefore, the SIF was utilized to characterize the crack singularities in terms of the local crack-opening displacement.…”

Section: (B)supporting

confidence: 59%

“…The weld was meshed using a finer element to account for the adequate gradients in model's heat source. The Gaussian-heat-flux-source model was used because it is the fundamental heat-source model for performing TM-FEM analyses [21]. The thermal boundary conditions combined with the heat exchange from both convection and radiation were applied to the upper surfaces of the weld components.…”

Section: Thermo-mechanical Modelingmentioning

confidence: 99%

“…The brittle nature of solidification cracking leads to the consideration of crack growth as a fracture problem that falls into the framework of linear elastic fracture mechanics (LEFM) [4][5][6]21]. Furthermore, XFEM has been proven to be effective in modeling brittle and ductile fractures and is, therefore, introduced here for the modeling of the solidification-cracking evolution.…”

Section: Introductionmentioning

confidence: 99%

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Solidification Crack Evolution in High-Strength Steel Welding Using the Extended Finite Element Method

2020

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High-strength steel suffers from an increasing susceptibility to solidification cracking in welding due to increasing carbon equivalents. However, the cracking mechanism is not fully clear for a confidently completely crack-free welding process. To present a full, direct knowledge of fracture behavior in high-strength steel welding, a three-dimensional (3-D) modeling method is developed using the extended finite element method (XFEM). The XFEM model and fracture loads are linked with the full model and the output of the thermo-mechanical finite element method (TM-FEM), respectively. Solidification cracks in welds are predicted to initiate at the upper tip at the current cross-section, propagate upward to and then through the upper weld surface, thereby propagating the lower crack tip down to the bottom until the final failure. This behavior indicates that solidification cracking is preferred on the upper weld surface, which has higher weld stress introduced by thermal contraction and solidification shrinkage. The modeling results show good agreement with the solidification crack fractography and in situ observations. Further XFEM results show that the initial defects that exhibit higher susceptibility to solidification cracking are those that are vertical to the weld plate plane, open to the current cross-section and concentratedly distributed compared to tilted, closed and dispersedly distributed ones, respectively.

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Section: (B)supporting

confidence: 59%

Section: Thermo-mechanical Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solidification Crack Evolution in High-Strength Steel Welding Using the Extended Finite Element Method

2020

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“…The dendrite shape and solute concentration that micro-scale models predict can be used to investigate new materials to be used in AM. Having an estimate on element phases and solute concentration can help in knowing if defects like hot cracking are likely to form or segregation of alloying elements (Keller, Lindwall et al 2017, Gao, Agarwal et al 2018).…”

Section: Potential and Challenges Of Microstructure Modelling In Ammentioning

confidence: 99%

Microstructure modelling for metallic additive manufacturing: a review

Tan

Sing

Yeong

2019

Virtual and Physical Prototyping

199

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The microstructure of metal built using AM is highly dependent on the process parameters. However, experimentation on different process parameters for different materials is costly and time consuming. To overcome these challenges, numerical simulations provide insights that allow prediction of microstructure formed under different process parameters. Microstructure modelling requires coupling of macro-scale thermal model or experimentally measured temperature profiles with either a meso-scale or micro-scale microstructure model. In this review, the commonly used AM techniques for metals are introduced, followed by discussion on the microstructure of parts fabricated using these processes. This review then presents the latest models used in simulating different microstructural aspects of metal AM parts. In addition, the models were compared and the potential and challenges in microstructure modelling were discussed.

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“…There are also some simulation works conducted from the perspective of microstructure characterization to gain a better understanding of the process [13,4,55]. Gao et al [18] studied the hot cracking in laser welding with a multi-scale modeling approach, where the thermal field is calculated with the finite element method and microstructural evolution by phase-field modeling. Vrancken et al [52] combined thermo-mechanical simulations with in situ high-speed videos of microcracking in single laser-melted tracks and found microcracking occurs in a narrow temperature interval.…”

Section: Introductionmentioning

confidence: 99%

A thermo-mechanical phase-field fracture model: application to hot cracking simulations in additive manufacturing

Ruan¹,

Rezaei²,

Yang³

et al. 2022

Preprint

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Thermal fracture is prevalent in many engineering problems and is one of the most devastating defects in metal additive manufacturing. Due to the interactive underlying physics involved, the computational simulation of such a process is challenging. In this work, we propose a thermo-mechanical phase-field fracture model, which is based on a thermodynamically consistent derivation. The influence of different coupling terms such as damage-informed thermomechanics and heat conduction and temperature-dependent fracture properties, as well as different phase-field fracture formulations, are discussed. Finally, the model is implemented in the finite element method and applied to simulate the hot cracking in additive manufacturing. Thereby not only the thermal strain but also the solidification shrinkage are considered. As for thermal history, various predicted thermal profiles, including analytical solution and numerical thermal temperature profile around the melting pool, are regarded, whereas the latter includes the influence of different process parameters. The studies reveal that the solidification shrinkage strain takes a dominant role in the formation of the circumferential crack, while the temperature gradient is mostly responsible for the central crack. Process parameter study demonstrates further that a higher laser power and slower scanning speed are favorable for keyhole mode hot cracking while a lower laser power and quicker scanning speed tend to form the conduction mode cracking. The numerical predictions of the hot cracking patterns are in good agreement with similar experimental observations, showing the capability of the model for further studies.

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Hot cracking investigation during laser welding of high-strength steels with multi-scale modelling approach

Cited by 18 publications

References 23 publications

Solidification Crack Evolution in High-Strength Steel Welding Using the Extended Finite Element Method

Solidification Crack Evolution in High-Strength Steel Welding Using the Extended Finite Element Method

Microstructure modelling for metallic additive manufacturing: a review

A thermo-mechanical phase-field fracture model: application to hot cracking simulations in additive manufacturing

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