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Showing 25 results for Joint

M. Naseri Alenjagh, T. Saeid,
Volume 9, Issue 1 (5-2023)
Abstract

The purpose of this research is to investigate the change of rotational speed and traverse speed on the microstructure and mechanical properties of the joint in friction stir welding of aluminum 1050 and 316L stainless steel. For this purpose, the microstructure, thickness of intermetallic compounds, hardness and tensile test on the joint were investigated. The proper selection of welding parameters leads to the creation of a joint with suitable metallurgical and mechanical properties. In this research, two rotational speeds of 560 and 900 rpm and four traverse speeds of 60, 80, 100 and 125 mm/min were performed. The microstructure consisted of four areas of the base metal, heat affected zone, thermo-mechanical affected zone and stir zone. In all the samples, the stir zone (SZ) contained a recrystallization microstructure with fine equiaxed grains. According to the Energy dispersive X-ray Spectroscopy results, an IMC layer formed in the joint interface. The hardness of the stir zone in all samples was higher than the aluminum base metal due to the formation of recrystallization fine equiaxed grains and the presence of steel particles. The best sample in terms of mechanical properties, mocrostructure and joint quality was obtained in the conditions of rotation speed of 900 rpm and advance speed of 125 mm/min. The strength was equal to 84 MPa with 77% efficiency.

Mr E. Ganjeh, Dr Ali Kaflou, Dr Kourosh Shirvani,
Volume 9, Issue 2 (1-2024)
Abstract

In this study, mechanical properties of the transient liquid phase (TLP) bonds between Hastelloy X to Ni3Al IMC at temperature range of 800 - 900 °C were investigated. The microstructure of the joints was examined by optical and scanning electron microscopy. Also, high temperature XRD (HTXRD) analysis was utilized to investigate the phase changes at different temperatures of half-joints. According to microscopic observations, the joint cross-section consisted of three regions including diffusion affected zone (DAZ), isothermal solidification zone (ISZ), and Athermal solidification zone (ASZ), which increasing temperature and time result in ISZ consisting of nickel-rich solid solution developed across the microstructure. The optimum joint bonding strength was achieved for the sample treated at 1100 °C – 180 min equal to 355 ± 4.5 MPa. The ultimate tensile strength reached 36.5 ± 1 and 20.5 ± 1 MPa at temperatures of 800 °C and 900 °C, respectively. Fracture occurred on the side of the IMC substrates at both test temperatures due to the presence of shrinkage porosity during the solidification stage of IMC and crystal lattice parameters mismatch with the matrix.

M.r Borhani, S.r. Shoja-Razavi, F. Kermani,
Volume 10, Issue 1 (6-2024)
Abstract

In this study, the effects of friction stir welding (FSW) parameters on the properties of dissimilar joints formed between 5083 aluminum alloys and 316L austenitic stainless steel, with a thickness of 4 mm, are investigated. The tool speed is varied in the range of 16 to 25 mm/min, while the tool rotation speed is maintained at a constant value of 250 rpm. To examine the microstructure of different weld regions, both optical and scanning electron microscopes are employed. To assess the mechanical properties, hardness and tensile tests are conducted. The results shows the formation of a composite region characterized by steel reinforcement particles dispersed within an aluminum matrix. At the steel-aluminum interface, a single layer of discontinuous intermetallic composition with a thickness of approximately 2 micrometers is observed. Notably, when the rotation speed is set to 250 rpm and the tool speed is 16 mm/min, a tensile strength of 298 MPa and ductility of 26% (93% of the tensile strength and 50% of the ductility of the 5083 aluminum alloy) are achieved.

Gh. Khalaj, J. Khalaj, F. Soleymani,
Volume 10, Issue 1 (6-2024)
Abstract

In this study, the microstructure of the joint interface in three-layer explosive welding of austenitic stainless steel 321 - aluminum 1050 - aluminum 5083 was examined before and after heat treatment. The welded samples were subjected to heat treatment at temperatures of 250°C and 350°C for durations of 1000, 3000, and 10000 seconds. Microstructural analysis was performed using optical microscopy and scanning electron microscopy. The results revealed that under all conditions, the Joint Interface of aluminum 5083 - aluminum 1050 exhibited a flat and defect-free structure. With increasing standoff distance, the Joint Interface of stainless steel 321 - aluminum 1050 transitioned from a smooth to a wavy pattern, and the average layer thickness increased from 4.95 μm to 6.7 μm. During heat treatment, the layer thickness in the Joint Interface increased proportionally to the diffusion kinetics, reaching maximum values of 18.56 μm and 15.02 μm for samples with standoff distances of 6.75 mm and 6 mm, respectively. The activation energies for diffusion were calculated as 46.6 kJ/mol and 42.4 kJ/mol, and the diffusion constants were 142.2 ms-1  and 45.3 ms-1 for the same samples.


 
M. Taheri, Gh. Azimiroeen, M. Shamanian, A. Bahrami,
Volume 10, Issue 1 (6-2024)
Abstract

The dissimilar joint of alumina to copper with active filler metals Ag-Cu-Ti-Sn and Ag-Cu-Ti-Sn-%3.5Zr were done using the induction brazing process at temperatures of 840 and 860 ℃ for 15 minutes. The microstructures of joints were evaluated using optical microscope (OM) and scanning electron microscope (SEM). Vickers hardness test and shear tensile strength test were used to evaluate the mechanical properties. The results of the microstructural studies showed that the Al2O3/Cu joints using Ag-Cu-Ti-Sn and Ag-Cu-Ti-Sn-%3.5Zr fillers contain a reaction layer at the interface between alumina and the filler metal. At the area of the reaction layer with Ag-Cu-Ti-Sn filler metal, two TiO and Cu3Ti3O phases were observed, and also at the reaction layer with Ag-Cu-Ti-Sn-%3.5Zr filler metal, two TiO and ZrO2 phases were observed. The results of the shear strength test showed that due to the greater thickness of the filler metal and the lower thickness of the reaction layer, the joint with the filler metal Ag-Cu-Ti-Sn-%3.5Zr (14 MPa) has a higher shear strength as compared with the joint with filler metal Ag-Cu-Ti- Sn (9 MPa).


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