Achieving excellent microformability in aluminum by engineering a unique ultrafine-grained microstructure

Dhal, A.; Panigrahi, S. K.; Shunmugam, M.S.

doi:10.1038/s41598-019-46957-4

Cited by 16 publications

(8 citation statements)

References 35 publications

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“…A study 40 reported that the grains are elongated in the highly stressed cup region. However, when the initial grain size is already elongated, there is no appreciable change in grain length at the length scale of 250 microns.…”

Section: Resultsmentioning

confidence: 99%

Hybrid optimisation of input process parameters of deep-drawn cylindrical cups from directional rolled copper strips

Sivam

Rajendran

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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Deep drawing is a method of producing sheet metal. It is extensively used in the automobile, packaging and home appliance industries. Incorrect parameter selection might induce defects in stamped components. Trial and error can improve product accuracy, but at the expense of execution and calculation. An optimisation approach and a response surface model are used to determine the optimal parametric parameter design. This study proposes a full and efficient optimisation approach, starting with modelling by RSM (Response Surface Methodology) and concluding with optimal process parameter identification. Based on this, a neural network was developed to improve cylindrical cup deep drawing. Three characteristics of fabricating the cups are clearance, punch radius and coefficient of friction. This parameter demonstrates the resultant tool force, spring back, maximum forming limiting curve and maximum thinning rate of cylinder cups. Initially, the three inputs are varied to measure the outcome using simulation software by Altair inspire form. Then, the equations for each output are designed using quadratic-based linear model fitting. The generated objective function is then used to establish the ideal process parameters for the cylindrical cups. The proposed method is compared to real-time physical experiments. The optimised parameter microstructure at the high-stress zone and the product quality are satisfactory without defects.

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Section: Resultsmentioning

confidence: 99%

Hybrid optimisation of input process parameters of deep-drawn cylindrical cups from directional rolled copper strips

Sivam

Rajendran

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…As pointed out above, the activation of dislocation sources contributes to dislocation generation. Cold deformation can promote the transformation of equiaxed grains into elongated ones, and grain boundary-mediated plasticity can result in stress-assisted grain growth because of the migration, rotation, and coalescence of the grains in a preferred direction for accommodating the strain paths [45,46]. Besides, the formation of slip bands in the grains is evident, eventually revealing the localization of plastic deformation [47].…”

Section: Complete Tensile Testmentioning

confidence: 99%

“…TEM analysis points to the presence of a high density of DTs. In materials being characterized by facilitated cross slip, as is the case for cp-Fe, the formation of DTs and further LAGBs can occur [46]. Eventually, in cases of intense dislocation motion at higher strains, barriers that initially require low energy to be overcome by dislocations can consolidate, evolving into grain boundaries of low misorientation angle, and finally resulting in HAGBs at the highest deformations (if localized cracking does not set in earlier).…”

Section: Process-microstructure-property-relationshipsmentioning

confidence: 99%

Influence of Various Processing Routes in Additive Manufacturing on Microstructure and Monotonic Properties of Pure Iron—A Review-like Study

Torrent,

Sajadifar,

Gerstein

et al. 2024

Metals

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Additive manufacturing processes have attracted broad attention in the last decades since the related freedom of design allows the manufacturing of parts with unique microstructures and unprecedented complexity in shape. Focusing on the properties of additively manufactured parts, major efforts are made to elaborate process-microstructure relationships. For instance, the inevitable thermal cycling within the process plays a significant role in microstructural evolution. Various driving forces contribute to the final grain size, boundary character, residual stress state, etc. In the present study, the properties of commercially pure iron processed on three different routes, i.e., hot rolling as a reference, electron powder bed fusion, and laser powder bed fusion, using different raw materials as well as process conditions, are compared. The manufacturing of the specimens led to five distinct microstructures, which differ significantly in terms of microstructural features and mechanical responses. Using optical and electron microscopy as well as transmission electron microscopy, the built specimens were explored in various states of a tensile test in order to reveal the microstructural evolution in the course of quasistatic loading. The grain size is found to be most influential in enhancing the material’s strength. Furthermore, substructures, i.e., low-angle grain boundaries, within the grains play an important role in terms of the homogeneity of strain distribution. On the contrary, high-angle grain boundaries are found to be regions of strain localization. In summary, a holistic macro-meso-micro-nano investigation is performed to evaluate the behavior of these specific microstructures.

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“…Rosochowski et al already showed in 2007, by using micro-cup extrusion tests, that the use of nano-crystalline microstructures can improve the homogeneity of the material flow and the surface quality in bulk microforming processes [13]. Dahl et al have proven in deep drawing tests that compared to conventional grain structures, the use of nano-crystalline grain structures can significantly improve the surface quality, the dimensional stability and the process scattering in micro sheet forming [14]. Thus, the microstructure of the material AA6014 is modified to this state by using an accumulative roll bonding (ARB) process.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Size Effects in Multi-Stage Cold Forming of Metallic Micro Parts from Sheet Metal

Kraus

Merklein

2021

Micromachines

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Product miniaturisation and functional integration are currently global trends to save weight, space, materials and costs. This leads to an increasing demand for metallic micro components. Thus, the development of appropriate production technologies is in the focus of current research activities. Due to its efficiency, accuracy and short cycle times, microforming at room temperature offers the potential to meet the steadily increasing demand. During microforming, size effects occur which negatively affect the part quality, process stability, tool life and handling. Within this contribution, a multi-stage bulk microforming process from sheet metal is investigated for the materials Cu-OFE and AA6014 with regard to the basic feasibility and the occurrence of size effects. The results reveal that the process chain is basically suitable to produce metallic micro parts with a high repeatability. Size effects are identified during the process. Since several studies postulate that size effects can be minimised by scaling down the metallic grain structure, the grain size of the aluminium material AA6014-W is scaled down to less than one micrometre by using an accumulative roll bonding process (ARB). Subsequently, the effects of the ultrafine grain (UFG) structure on the forming process are analysed. It could be shown that a strengthened material state increases the material utilization. Furthermore, too soft materials can cause damage on the part during ejection. The occurring size effects cannot be eliminated by reducing the grain size.

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Achieving excellent microformability in aluminum by engineering a unique ultrafine-grained microstructure

Cited by 16 publications

References 35 publications

Hybrid optimisation of input process parameters of deep-drawn cylindrical cups from directional rolled copper strips

Hybrid optimisation of input process parameters of deep-drawn cylindrical cups from directional rolled copper strips

Influence of Various Processing Routes in Additive Manufacturing on Microstructure and Monotonic Properties of Pure Iron—A Review-like Study

Investigation of Size Effects in Multi-Stage Cold Forming of Metallic Micro Parts from Sheet Metal

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