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American Society for Testing and Materials

Necking and fracture limit analyses of different pre-strained sheet materials in polar effective plastic strain locus using Yld2000-2d yield model

Experimental and theoretical investigations of the forming limit of 5754O aluminum alloy sheet under different combined loading paths

Prediction of earing defect and deep drawing behavior of commercially pure titanium sheets using CPB06 anisotropy yield theory

Stress relaxation during plastic deformation has been reported to improve ductility and alter the mechanical properties of metallic materials. The aim of the present study is to investigate...

Investigation of stress relaxation mechanisms for ductility improvement in SS316L

Formability analysis of pre-strained AA5754-O sheet metal using Yld96 plasticity theory : role of amount and direction of uni-axial pre-strain

This paper investigated various aspects of replacing existing micro-resistance spot welding (micro-RSW) with micro-laser spot welding for joining Inconel 718 thin foils to thick 410 steel stack-up to allow faster, non-contact joining together with flexibility in spot positioning and removal of tip dressing required for RSW electrodes. The joint quality was evaluated based on the mechanical strength, microstructural characteristics and joint strength at elevated temperature as these joints are often used for high-temperature applications. Experimental investigations were performed using micro-RSW and micro-laser spot welding to obtain the 90° peel and lap shear specimens, each comprising four spots. The obtained strength from laser joints was significantly higher than that of micro-RSW joints due to larger weld nugget formation and interface width. The process map for obtaining good quality welds was also identified, and about a 17% reduction in joint strength was obtained when welded specimens were subjected to elevated temperature (i.e., 500 °C) in comparison with room temperature. This reduction was compensated for using the flexibility of laser welding to add two extra spots. The overall performance of the micro-laser spot welds was found to be better than the micro-RSW considering joint strength, flexibility in placing the spots and time to produce the welds.

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Substituting Resistance Spot Welding with Flexible Laser Spot Welding to Join Ultra-Thin Foil of Inconel 718 to Thick 410 Steel

AA6010 in the F temper was investigated using a Gleeble 3800 test rig across a range of temperatures (350–550 °C) and strain rates (1 × 10−1 s−1 1 × 101 s−1) to identify optimal forming conditions. Post-forming electron back-scattered diffraction analysis was conducted to identify the mechanisms responsible for the material formability. Optimal forming conditions were observed to be 500 °C and a strain rate of 1 × 10−1 s−1, with clear evidence of dynamic recrystallisation observed, this being the dominant mechanism responsible for the increased formability. Peak yield strength of 335 MPa was achieved using a rapid aging treatment of 205 °C for one hour.

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Identifying Optimal Hot Forming Conditions for AA6010 Alloy by Means of Elevated Temperature Tensile Testing

Utilising blue laser over infrared laser to enhance control of penetration depth and weld strength for producing electric vehicle battery interconnects

Strain path change is a typical phenomenon during continuous stamping operations of sheet metal for a variety of applications including automotive body parts. During stamping, a punch continuously deforms a metal sheet to produce a desired geometry while following various strain path transitions depending on overall design of the stamping process. The strain path change can potentially alter the expected forming limit of the material. Previous researchers investigated the effect of changing strain path by loading sample in two distinct steps. Typically, between the steps the sample is unloaded before being re-loaded in the new strain path. This practice reflects the key challenge in elucidating this strain path dependent deformation, which is the ability to control the strain path change in a single deformation stage in an experimental set-up. In this work, a novel testing rig and specimen geometry that is capable of changing the strain path of a sample continuously without unloading the specimen were conceptualised, modelled and subsequently manufactured. Using this apparatus, the specimen was deformed in the uniaxial strain path in the first step before being deformed biaxially without unloading in between the steps. Thus, the apparatus ensures that the sample undergoes a continuous strain path change without unloading between the steps. The size of this mechanical test rig permits it to be placed inside a scanning electron microscope (SEM) chamber in order to study strain path transition in-situ to highlight strain localization and related microstructural changes in real time. Utilizing this test set-up, strain path change and corresponding strain values along each strain path were evaluated. The changes in material microstructure were concurrently investigated using in-situ SEM and electron back scattered diffraction (EBSD) analysis.

Sisir Dhara

Papers

Formability analysis of pre-strained AA5754-O sheet metal using Yld96 plasticity theory : role of amount and direction of uni-axial pre-strain

Substituting Resistance Spot Welding with Flexible Laser Spot Welding to Join Ultra-Thin Foil of Inconel 718 to Thick 410 Steel

Identifying Optimal Hot Forming Conditions for AA6010 Alloy by Means of Elevated Temperature Tensile Testing

Utilising blue laser over infrared laser to enhance control of penetration depth and weld strength for producing electric vehicle battery interconnects

A novel experimental set-up for in-situ microstructural characterization during continuous strain path change