Showing 4 results for Magnesium Alloy
. S. Khani, . M. T. Salehi, . H. R. Samim, Prof. M. R. Aboutalebi, . H. Palkowski,
Volume 13, Issue 3 (9-2016)
Abstract
The evolution of microstructure and mechanical properties of a magnesium cast alloy (AZ31) processed by equal channel angular pressing (ECAP) at two different temperatures were investigated. The as-cast alloy with an average grain size of 360 was significantly refined to about 5 after four ECAP passes at 543 K. Grain refinement was achieved through dynamic recrystallization (DRX) during the ECAP process in which the formation of necklace-type structure and bulging of original grain boundaries would be the main mechanisms. ECAP processing at lower temperature resulted in finer recrystallized grains and also a more homogenous microstructure. The mechanical behavior was investigated at room temperature by tensile tests. The obtained results showed that the ECAP processing can basically improve both strength and ductility of the cast alloy. However, the lower working temperature led to higher yield and ultimate strength of the alloy.
M. Hoghooghi, O. Jafari, S. Amani, G. Faraji, K. Abrinia,
Volume 16, Issue 4 (12-2019)
Abstract
Spread extrusion is a capable method to produce different samples with a wider cross-section from the smaller billets in a single processing pass. In this study, dish-shaped samples are successfully produced from the as-cast cylindrical AM60 magnesium alloy at 300 °C, the mechanical properties and microstructural changes of the final specimens are precisely evaluated. Due to the high amount of plastic strain, which is applied to the initial billet during the material flow in the expansion process, grain refinement occurred as a result of recrystallization and subsequently good mechanical properties achieved. Therefore, mean grain size reduced from 160 µm to 14 µm and initial equiaxed grains changed to the elongated ones surrounded by fine grains. Also, microhardness measurements indicate that hardness increased from 51 Hv to 70 Hv. Some fluctuations were also observed in the hardness profile of the sample which was mainly related to the bimodal structure of the final microstructure. Good mechanical properties, fine microstructure, and also the ability to produce samples with higher cross-section make the spread extrusion process a promising type of extrusion.
Amir Mostafapour, Milad Mohammadi, Ali Ebrahimpour,
Volume 18, Issue 2 (6-2021)
Abstract
A full factorial design of experiment was applied running 36 experiments to investigate the effects of milling parameters including cutting speed with three levels of 62.83, 94.24 and 125.66 m/min, feed rate with three levels of 0.1, 0.2 and 0.3 mm/tooth, cutting depth with two levels of 0.5 and 1 mm and machining media with two levels, on surface integration properties of magnesium AZ91C alloy such as grain size, secondary phase percent, surface microhardness and surface roughness. In all cases, a fine grained surface with higher secondary phase sediment and microhardness obtained comparing the raw material. According to analysis of variance results, the most effective parameter on grain size, secondary phase percent and microhardness was cutting depth and the most effective parameter on surface roughness was feed rate. although the grain size in all machined samples was smaller than that of the raw material but due to the dual effect of cryogenic conditions, which both cool and lubricate and reduce the temperature and strain rate at the same time, the direct effect of this parameter on grain size was not significant. Also, the all interaction effects of parameters on grain size and microhardness were significant.
Ata Abdi, Mehrdad Aghaie-Khafri,
Volume 19, Issue 1 (3-2022)
Abstract
Hot Workability and Processing Map of High Gd Content Mg-Gd-Zn-Zr-Nd Alloy Hot deformation behavior of homogenized Mg-4Sn binary alloy was studied using compression tests at the temperature range of 300-500
and strain rates of 0.001-1s
-1. The material showed typical single peak flow behavior followed by a steady state flow as a plateau, which is more evident at the high value of Zener-Hollomon parameter. Constitutive analysis showed that in spite of the original Johnson-Cook (J-C), conventional strain compensated Arrhenius model based on Sellars-McTegart model has a reasonable agreement with the experimental data. Moreover, the well-known hyperbolic sine function fits the experimental data for predicting of the peak stress with a fair degree of accuracy.
