Showing 4 results for Heidarzadeh
Mr. Mohammad Karimi Dizaj Cheragh, Dr. Moosa Sajed, Dr. Mohammad Ali Saeimi Sadigh, Dr. Arezou Abyazi, Akbar Heidarzadeh,
Volume 9, Issue 2 (Journal OF Welding Science and Technology 2025)
Abstract
This study experimentally investigates the repair of surface grooves on pure magnesium samples using the surface friction stir processing (SFSP). Grooves with depths of 0.5, 1, and 1.5 mm were created and subsequently repaired under constant parameters of 1400 rpm rotational speed and 40 mm/min travel speed. The results revealed that the stir zone (SZ) exhibited fine equiaxed grains due to complete dynamic recrystallization, leading to significant improvements in tensile strength and hardness compared to the base metal. The highest ultimate tensile strength of 66.1 MPa and hardness of 60 HV were achieved in the 1 mm groove sample. Additionally, partial dynamic recrystallization was observed in the thermo-mechanically affected zone (TMAZ), and complete elimination of grooves was confirmed in all samples. These findings demonstrate that the SFSP is highly effective for localized repair and enhancement of mechanical properties in magnesium components, offering a promising solution to extend the service life of damaged magnesium parts.
Mr. Ramin Dadashpour, Dr. Moosa Sajed, Dr. Mohammad Ali Saeimi Sadigh, Dr. Arezou Abyazi, Dr. Akbar Heidarzadeh,
Volume 9, Issue 2 (Journal OF Welding Science and Technology 2025)
Abstract
In this study, the Friction Stir Welding process was employed to repair artificial cracks and grooves in 7075 aluminum alloy. Samples with different groove depths (0.5, 1, 1.5, and 2 mm) were prepared and evaluated through experimental tests, metallographic analysis, tensile testing, and numerical simulation using Abaqus software. The results showed that the Friction Stir Welding successfully repaired the defects without creating voids or surface irregularities. Microstructural observations in the stir zone revealed that dynamic recrystallization led to the formation of fine and homogeneous grains, resulting in improved hardness and tensile strength. The specimen with a 1 mm groove depth exhibited the best mechanical performance, with a maximum hardness of approximately 109 HV and the highest tensile strength among all samples. Conversely, samples with 0.5 and 2 mm groove depths showed void formation and reduced strength due to insufficient or excessive heat input and uneven material flow. Both experimental and simulation results confirmed that a groove depth of 1 mm provides optimal conditions for defect repair in 7075 aluminum alloy.
A. Heidarzadeh, R. Khajeh, M. Sajed,
Volume 10, Issue 2 (Journal OF Welding Science and Technology 2024)
Abstract
In this research, the effect of nickel powder as an interlayer and the tool penetration depth on the microstructure and mechanical properties of lap joints between aluminum 1050 (top sheet) and pure copper (bottom sheet), both with a thickness of 2 mm, was investigated. Nickel powder was added through a machined groove with a width and depth of 1 mm at the base of the aluminum sheet. Friction stir lap welding was performed using a hot work steel tool with a shoulder diameter of 16 mm, a pin diameter of 4 mm, a pin height of 2.1 mm, a rotational speed of 950 rpm, a feed rate of 85 mm/min, a tool tilt angle of 2°, and varying tool penetration depths of 0, 0.05, and 0.1 mm. The results revealed that in the sample with a 0 mm penetration depth, due to insufficient heat generation, defects such as tunnel voids were formed. Increasing the penetration depth to 0.05 mm resulted in the formation of uniform and thin intermetallic layers, including Al3Ni2, Al7Cu4Ni, and Cu3.8Ni at the interface, which enhanced joint quality and increased tensile strength to 185.2 MPa with a fracture strain of 8.7%. In the sample with a 0.1 mm penetration depth, thicker and less uniform intermetallic layers were formed, which, despite locally increasing hardness, led to a decrease in tensile strength and fracture strain to 136.6 MPa and 6.7%, respectively. This study demonstrates that under the conditions of this research, a tool penetration depth of 0.05 mm provides the optimal conditions for FSLW of aluminum-copper alloys using nickel powder.
H.g. Tehrani-Moghadam, H.r. Jafarian, M. Aghazadeh Ghomi, A. Heidarzadeh,
Volume 11, Issue 1 (Journal OF Welding Science and Technology 2025)
Abstract
In this study, the effect of friction stir welding on the microstructure and mechanical properties of Fe-24Ni-4Cr austenitic steel was investigated. For this purpose, a sheet with a thickness of 1 mm was subjected to friction stir welding using a WC-5%Co tool at a traverse speed of 100 mm/min and a tool rotational speed of 450 rpm. Electron backscatter diffraction (EBSD) analysis revealed that this process led to grain refinement and an increase in high-angle grain boundaries in the stir zone, attributed to dynamic recrystallization during welding. Phase maps indicated an increase in the BCC phase fraction in the stir zone compared to the base metal. Given the high strain rate and the presence of stabilizing elements, this phase was primarily strain-induced martensite. Mechanical property assessments showed a significant increase in the tensile strength of the stir zone (450 MPa) compared to the base metal (350 MPa). Moreover, the yield strength of the stir zone (388 MPa) was substantially higher than that of the base metal (145 MPa), which can be attributed to grain refinement, an increase in high-angle grain boundaries, a higher dislocation density, and martensite formation. However, the ductility of the stir zone decreased due to higher stress concentration and dislocation density in this region. These findings suggest that friction stir welding can be an effective method for enhancing the strength and hardness of austenitic steels, but process conditions must be carefully controlled to prevent reductions in toughness and ductility.
