Microstructure and Properties of Engineering Materials

Clemens, Helmut; Mayer, Svea; Scheu, Christina

doi:10.1002/9783527684489.ch1

Cited by 21 publications

(18 citation statements)

References 25 publications

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“…The two mentioned features are essential indicators of structural characteristics for a polycrystalline material [8,19] that can change during the ultrasonic welding process. Furthermore, the atomic mismatch between two adjacent grains or crystals that have different crystallographic orientations next to a grain boundary is common and has mostly been considered as an interfacial defect [11]. Microsection observations showed that the process parameters impact the grain size, particularly at the joint interface.…”

Section: Microscopic Observationsmentioning

confidence: 99%

Molecular dynamics simulation of interface atomic diffusion in ultrasonic metal welding

Mostafavi

Bamer

Markert

2021

Int J Adv Manuf Technol

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The formation of a reliable joint between a large number of aluminum strands for battery applications is crucial in automotive industry, especially in the technology of autonomous vehicles. Therefore, in this study, mechanical deformations and diffusion patterns of the mating interface in ultrasonic welding of aluminum were investigated using molecular dynamics simulations. Furthermore, microscopic observations of the joints between aluminum strands from ultrasonic welding illustrating the influence of two process parameters were done. To study the nanomechanics of the joint formation, two aluminum crystallites of different orientations were built. The impact of the sliding velocity and the compression rate of the upper crystal block on the diffusion pattern at the interface of the two crystallites were quantified via the diffusion coefficient. Tensile deformations of several joint configurations were performed to investigate the load-bearing capacity of the solid state bond, taking into account the compression rate, the sliding velocity and the crystallite orientation. The atomic scale simulations revealed that the orientations of the crystallites govern the interface diffusion and the tensile strength of the joint significantly. Furthermore, interface atom diffusion increased with increasing the sliding velocity. Additionally, it was observed that a higher sliding velocity enhances the friction heat generation between the crystallites and significantly increases the interface temperature.

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Section: Microscopic Observationsmentioning

confidence: 99%

Molecular dynamics simulation of interface atomic diffusion in ultrasonic metal welding

Mostafavi

Bamer

Markert

2021

Int J Adv Manuf Technol

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“…This institutes a stress concentration ahead of the slip planes, initiating new dislocations at the nearby grains [34]. The fine-grain structures are harder and stronger in comparison to the coarse-grained structures because the total grain boundary area required to hinder the dislocation movement is more in fine-grained structures [35].…”

Section: Optical Microscopymentioning

confidence: 99%

Utilizing the water hammer effect to enhance the mechanical properties of AISI 304 welded joints

Srivastava

Hloch

Krejčí

et al. 2021

Int J Adv Manuf Technol

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The local residual stresses (tensile) generated on the surface of a component during its manufacturing (machining, welding) cause deterioration of its service life. To eliminate the negative effect of the stresses, the surface is treated using different methods (shot peening, laser shock peening, heat treatment, water jet peening). The application of ultrasonic technology to modify the continuous jet has been intensively researched for treating advanced stages of erosion. In this work, the modifications in the mechanical properties (tensile strength, micro-hardness and residual stress measurements) of AISI 304 Tungsten inert gas welded joints were investigated after ultrasonic pulsating water jet treatment in the incubation stage of erosion. This revealed that the initial tensile residual stress in the welded joints was converted to compressive stress after the treatment. The micro-hardness of the joints after the treatment increased about 40% in the heat affected zone in the near-surface region. Also, the tensile properties increased by about 37.8% and 34.6% in yield strength and ultimate strength, respectively. The microstructural examination of the near-surface region showed the grain reformation mechanism.

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“…Most material composition exhibits some kind of order at one or several spatial scales. For instance in the perfect order of the crystal lattice in a metal or the imperfect order in the arrangement of fibres and matrix in fibre-reinforced laminate, a number of spatial scales can be identified and distinguished with size and spacing having a typical order of magnitude Uchic et al (2004), Clemens et al (2017). Hence a particular controlling microstructural feature and a characteristic internal length can be readily identified Greer and De Hosson (2011), Isasti et al (2014).…”

Section: Introductionmentioning

confidence: 99%

Some Aspects on the Modelling of Microstructure Deformation Mechanisms with Gradient Truss Model (GTM) Bar Elements

Akintayo

2020

Lat. Am. j. solids struct.

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Unlike the classical truss model, the constitutive equation of the gradient truss model (GTM) earlier presented by the author introduces higher order strain gradient terms and a characteristic internal length parameter: Thus, considering the interaction between macroscopic and microscopic length scales in the constitutive response. Extra non-classical boundary conditions are required to solve the governing equation. In this paper, the microstructure of a material is defined in a simple manner by representing three typical underlying phenomena based on the spatial variation of strain and three combinations of extra non-classical boundary conditions of the derivative of displacement (strain) and higher order derivative of displacement (strain gradient) imposed at the bar support. To quantify the imposed strain gradient at the bar support, a simple relation is derived. Consequently, the influence of strain, strain gradient and the characteristic internal length parameter at the microstructure during deformation is readily captured and the three underlying phenomena qualitatively modelled by the three GTM bar elements. In addition, strengthening and weakening mechanisms in deformation are revealed. Numerical examples are presented as illustration.

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Microstructure and Properties of Engineering Materials

Cited by 21 publications

References 25 publications

Molecular dynamics simulation of interface atomic diffusion in ultrasonic metal welding

Molecular dynamics simulation of interface atomic diffusion in ultrasonic metal welding

Utilizing the water hammer effect to enhance the mechanical properties of AISI 304 welded joints

Some Aspects on the Modelling of Microstructure Deformation Mechanisms with Gradient Truss Model (GTM) Bar Elements

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