Effect of ECAE Die Angle on Microstructure Mechanical Properties and Corrosion Behavior of AZ80/91 Magnesium Alloys

Magnesium alloys have poor tensile strength, ductility and corrosion resistance properties associated with other engineering materials like aluminum alloys, steels and superalloys etc. Therefore, many researchers worked on equal channel angular pressing of magnesium alloys to improve the mechanical properties and corrosion resistance. In this work, the effect of channel angles on material properties was investigated during equal channel angular pressing of AZ80/91 magnesium alloy using processing route-R at 598 K processing temperature. Channel angles of 900 and 1100, common corner angle of 300 have been considered for the study. It has been revealed that the channel angle has a significant influence on deformation homogeneity, microhardness, ultimate tensile strength, ductility, and corrosion behavior of AZ80/91 magnesium alloys. Specifically, AZ80/91 Mg alloys processed through 900 channel angle i.e. die A is considered as optimal die parameter to improve above-said material properties. Investigation showing concerning as-received AZ80 and AZ91 Mg alloy indicates 11%, 14% improvement of UTS and 69%, 59% enhancement in ductility after processing through 4P through die A (90°) at 598 K respectively. Also, the corrosion rate reduces to 97% and 99% after processing the sample with 4P-ECAP die A (90°) at the same processing temperature for AZ80 and AZ91 Mg alloys respectively. This is mainly due to grain refinement and distribution of Mg17Al12 secondary phase during ECAP.

Microstructure and Properties of Bulk Ultrafine-Grained Cu1.5Cr0.1Si Alloy through ECAP by Route C and Aging Treatment

The evolutions of the microstructure and its effect on the mechanical and electrical conductivity properties of Cu1.5Cr0.1Si alloy after equal channel angle pressing (ECAP)-C path deformation and aging treatment have been investigated using scanning electron microscopy (SEM), x-ray diffraction (XRD), and electron back-scattered diffraction (EBSD). It was found that after the ECAP-C deformation at room temperature, with an extension of aging time, the strong (111) macro orientation formed in the Cu1.5Cr0.1Si alloy. The ultrafine crystals formed by ECAP and the rich chromium phase precipitated along grain boundaries during the aging process greatly improved the material strength. After aging at 350 °C for 4 h, the tensile strength, elongation, and conductivity reached 528 MPa, 15.27%, and 78.9% IACS, respectively. The fracture mode of the alloy was ductile fracture. The steady-oriented {111} <110> texture was beneficial to improving the conductivity of the material.

Synthesis of Al5083 Alloy by High Energy Ball Mill and Densification through Equal Channel Angular Pressing (ECAP)

An attempt was made to synthesis Al-5083alloy through high energy ball milling and densification through ECAP. The elemental powders consisting of Al5083 was milled for 5, 10 and 15 hrs using Retsch high energy ball mill (PM400). The physical and structural properties of mechanically alloyed particulates were characterised by diffraction methods and electron microscopy. The 15hrs nanocrystalline structured particulates of Al5083 alloy shows crystallite size of 15nm. Scanning Electron Microscope (SEM) reveals the morphology of alloy which is irregular shaped. The size of alloyed particulates also measured using SEM and found to be 7μm for 15hrs of milling. The 15hr milled alloy particulates were densified by ECAP through 90o die channel angle. Maximum densification of 92% and highest hardness of 63HRB was achieved for sample consolidated with route-A for two passes along with sintering.

Finite Element Analysis of Aluminum Alloy at Many Die Channel Angles Using DEFORM-3D

Equal channel angular pressing (ECAP) is a technique used to impose strain in material which helps to increase the mechanical properties of a material. It is generally used to refine grain size of the material by passing sample through equal channel. In this study, analysis on frictional effect in equal channel angular pressing using aluminum 1100 has been done by using FEM software DEFORM-3D version 10.1. Dies with different channel angle were designed with the help CATIA. This study shows the effect of friction with different die channel angle. It has been found that with the increase in friction, reduction in corner gap is found (dead zone), which may cause material damage and improve strain distribution homogeneity. The result obtained with FEM simulation are compared to those obtained theoretically, thus it is found that the current study is in good agreement to the theoretically result

Performance of the Cold-Bending Channel-Angle Buckling-Restrained Brace under Cyclic Loading

In this study, three restricted cold-bending channel-angle buckling-restrained brace (CCA-BRB) specimens were experimentally characterised by a low-reversed cyclic loading test. Three specimens had steel cores with cruciform cross section. Two restraining units were assembled to form an external constraint member, each of which was composed of an equilateral cold-bending channel and two equilateral cold-bending angles via welding. A gap or a thin silica gel plate was set between the internal core and the external constraint member to form an unbonded layer. Several evaluation parameters on the seismic performance, hysteretic behaviour, and energy dissipation capability of the CCA-BRB was investigated, including hysteresis curve, skeleton curve, compression strength adjustment factor, measured and computed stiffness, energy dissipation coefficient, equivalent viscous damping ratio, ductility coefficient, and cumulative plastic deformation. The test results and evaluation indices demonstrated that the hysteretic performance of braces with a rigid connection was stable. A Ramberg–Osgood model and two model parameters were calibrated to predict, with fidelity, the skeleton curve of CCA-BRB under cyclic load. The initial elastic stiffness of the brace used in practice should contain overall portions of the brace instead of the yielding portion of the brace. Finally, all the tested CCA-BRBs exhibited a stable energy absorption performance and verified the specimens’ construction was rational.