جستجوی مقالات مرتبط با کلیدواژه "mechanical property" در نشریات گروه "مکانیک"

In this paper, mechanical properties of welded single lap joints of pure aluminum sheets produced by severe plastic deformation (SPD) are considered. SPD in form of a large pre-strain was imposed to aluminum sheets through the constrained groove pressing (CGP) process. Furthermore, CGPed specimens are joined using the resistance spot welding (RSW) method. Welding time and force are maintained evenly. Welding current is raised until ideal failure mode is observed. Finally, mechanical properties of fusion zone, heat affected zone (HAZ) and base metal of welded SPDed specimens are derived. The results show that by increasing the pre-strain in specimens, an improvement in yield strength, ultimate tensile strength, load carrying capacity, maximum displacement before failure and nugget diameter is observed. Furthermore, sensitivity of these parameters to CGP pass number is considered. Finally, it has been shown that fusion zone and HAZ hardness values can increase by increasing the CGP pass number.

Conventional methods of composite production using friction stir processing are simple, rapid, and economical. However, homogenizing the reinforcing particles in the processing zone is very difficult. In addition, this method mainly focuses on surface composite production, while obtaining bulk composites is still challenging. This study investigates the production of AA3105-SiC aluminum matrix composite using the sandwich method as the manufacturing process. The SiC particles were applied through spraying as a layer between AA3105 aluminum sheets. Then, the effect of friction stir processing parameters is investigated. The results indicate an enhanced degree of stirring and plastic deformation following increasing the rotational to translational speed ratio (w / v), which leads to homogenization of the particle distribution in the aluminum matrix. By increasing the w / v ratio, the distribution coefficient decreases from 0.58 to 0.21, which indicates an improvement in the distribution of particles in the matrix. The friction stir processing using the sandwich method significantly improves the mechanical properties of the AA3105-SiC bulk composite compared with the processed samples without reinforcement, with a maximum increase of 192 % in ultimate tensile strength and 273 % in toughness at 1600 rpm and 31.5 mm/min.

During the solidification of binary metal alloys, chemical heterogeneities at product scale over a long distance range (1cm-1m) develop and this has detrimental effect on the resulting mechanical properties of cast products. Macrosegregation is of great concern to alloy manufacturers and end users as this problem persist. In this study, the use of process parameters namely casting speed and runner angle to reduce macro-segregation in aluminum-copper-zinc binary alloy solidification is reported. The results from optical microscope, scanning electron microscope and energy dispersive spectrometry show that these parameters significantly influenced the development, size and volume of macro-segregation. The combination of parameters namely the pouring height between 96 mm/s, 100mm/s, and runner angles between 1200, 1500 produced less segregations with improved mechanical properties within standard specification. The tensile strength (110 MPa), modulus of elasticity (6800 MPa) and 2.5 % elongation obtained in this study are within standard (88- 124 MPa), 7100 MPa and (1-25 %) respectively for this class of alloy.

Equal channel angular rolling (ECAR) is a severe plastic deformation method that covered plastic deformation of sheets. In this study, effects of ECAR route shave been investigated on the mechanical and microstructure properties of explosive-welded Al-Cu bimetal. At first, the explosive welding process has been performed to prepare the Al-Cu bimetals. Then, to relieve the stress and preparing of samples for ECAR process, the annealing process of the samples was done. Finally, the ECAR process was performed on the samples in two routes A and C. Results showed that yield and tensile strengths and micro hardness of ECARed samples significantly increased with increasing the number of passes, whereas their ductility decreased. The yield strength of bimetals has been increased from 80 MPa to 100 MPa and 130 MPa at the routes A and C, respectively. Also, with increasing the number of ECAR passes, the grain size of the ECARed bimetals decreased to about 2μm.