Showing 4 results for Shoja Razavi
H. Gorji, Dr. S. M. Barakat, S. R. Shoja Razavi, S. S. Babaie Sangetabi, M. Erfanmanesh,
Volume 8, Issue 1 (Journal OF Welding Science and Technology 2022)
Abstract
The aim of the present study is to investigate the mechanical and microstructural properties of 1.7225 steel in laser welding process using Nd:YAG pulsed laser device and then to determine the optimal focal length relative to the part in the welding area. After welding, microstructural characterization, microhardness and tensile tests were performed. Evaluations showed that the optimal focal length for welding of steel sheet 1.7225 with a thickness of 1 mm, it was about 9 mm and the focus was 1 mm below the surface of the part. Due to the high thermal concentration and cooling rate in laser welding, a completely martensitic microstructure has been observed in the molten and heat-affected regions of all specimens. In this alloy, the hardness of the base metal is 310±10 HV. After welding, the hardness of the sample with the optimal focal length has reached 625±10 HV in the heat affected zone and 730±10 HV in the melting zone. Also, the results of tensile test showed that the tensile properties of the sample with the optimal focal length were almost similar to the base steel and fracture was observed in the base steel region.
M.r. Borhani, S.r. Shoja Razavi, F. Kermani, M. Erfan Manesh, S.m. Barekat, H. Naderi Samani, M. Shahsavari,
Volume 8, Issue 2 (Journal OF Welding Science and Technology 2023)
Abstract
The purpose of this research is to laser cladding of stellite6 and stainless steel 17-4PH powders on the substrate of stainless steel 17-4PH, and investigate its solidification microstructure. The results showed that the microstructure of the stellite6 cladding has a cobalt solid solution ground phase with an FCC structure and Cr7C3 and Cr23C6 carbides. Also, the values of the primary dendrite distance and the distance of the secondary dendrite arm have decreased by moving away from the interface; The reason for this is related to the difference in the cooling rate in different parts of the coating. The microstructure of 17-4PH stainless steel coating includes martensitic, ferritic, and austenitic phases; Due to the same chemical composition of the substrate and the cladding, the weight percentage of elements such as iron, nickel, chromium, and copper did not change from the cladding to the interface. It indicates the uniformity of the chemical composition of the cladding and the substrate. The calculated microhardness for the cladding of stellite6, the substrate and the cladding of stainless steel 7-4PH is about 480, 350, and 350 respectively. The reason for the higher microhardness of the cladding is the presence of chromium carbides (Cr7C3 and Cr23C6) formed in the cobalt field and the cobalt solid solution field of the cladding.
Mohammad Reza Borhani, Reza Shoja Razavi, Farid Kermani,
Volume 9, Issue 2 (Journal OF Welding Science and Technology 2024)
Abstract
In this study, the effect of friction stir welding (FSW) parameters on the dissimilar joint properties of 5083 aluminum alloys and 316L austenitic stainless steel, with a thickness of 4 mm, has been investigated. The tool speed was considered in the range of 16 to 25 mm/min, and the rotation of tool speed was considered to be equal to a constant speed of 250 rpm. To check the microstructure of different weld areas, optical and scanning electron microscopes were used, to check the mechanical properties, hardness and tensile tests were performed. The results showed the formation of a composite region consisting of steel reinforcement particles in the field of aluminum.
At the steel-aluminum interface, a single layer of discontinuous intermetallic composition with a thickness of about 2 micrometers was observed; Also, by choosing the rotation speed of 250 rpm and the tool speed of 16 mm/min, the tensile strength equal to 298 MPa and ductility of 26% (93% of tensile strength and 50% of ductility of aluminum 5083 alloy) were obtained.
M. R. Borhani, M. Rajabi, R. Shoja Razavi, R. Jamaati,
Volume 9, Issue 2 (Journal OF Welding Science and Technology 2024)
Abstract
Reconstruction of parts using direct laser deposition can create a combination of high wear resistance properties, good toughness, and corrosion resistance. In this research, the wear properties of Inconel 625 powder cladding on the same substrate have been investigated; For this purpose, room temperature and high temperature wear tests have been used. Mass reduction, friction coefficient, width and depth of wear penetration have been measured. Also, a scanning electron microscope with an energy disspersive spectroscopy system was used to evaluate the cladding surface. The results showed that the mass reduction due to wear at Inconel 625 cladding compared to Inconel 625 substrate has decreased by 7% and 52%, respectively, at temperatures of 25°C and 620°C. Also, the wear mechanism of the room temperature of the cladding is mainly scratchy, and the wear mechanism of high temperature is mainly sticky.
