Showing 5 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.
Morteza Ilanlou, Reza Shoja Razavi, Pouya Pirali, Mohhamadreza Borhani,
Volume 9, Issue 2 (Journal OF Welding Science and Technology 2025)
Abstract
In this study, laser direct deposition was employed to fabricate a functionally graded transition between 17‑4PH stainless steel and Stellite 6. Specimens were designed and produced such that the chemical composition varied incrementally from 100 % 17‑4PH to 100 % Stellite 6, with each step involving a 25 % decrease in the 17‑4PH content and a corresponding 25 % increase in Stellite 6. Microstructural evolution and elemental distribution were characterized by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), while mechanical properties were assessed via Vickers microhardness testing and uniaxial tensile tests. The microstructural analysis revealed a needle‑like martensitic matrix in the substrate, which transformed into cellular dendrites upon reaching the 25 % Stellite 6 layer. As the Stellite 6 fraction increased, along with corresponding rises in Cr and W content, grain boundaries broadened and carbides accumulated within interdendritic regions. At the 50 % composition, oriented columnar dendrites became prominent, and at higher Stellite 6 levels the dendritic structure refined further, ultimately evolving into an equiaxed morphology. Microhardness measurements showed a continuous increase from approximately 300 HV in the 17‑4PH substrate to 490 HV in the pure Stellite 6 layer. Tensile testing demonstrated that both yield strength (σᵧ) and ultimate tensile strength (σᵤ) remained within 1102–1159 MPa across all compositions, with no evidence of brittle phases or manufacturing defects. Elongation increased from 7 % in pure Stellite 6 to 19 % in pure 17‑4PH, with the 50 %–50 % gradient exhibiting an optimal balance of strength and ductility (14.5 % elongation).
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.
B. Agharazi, S. R. Shoja Razavi, S. M. Barekat, M. R. Borhani, M. Erfanmanesh,
Volume 11, Issue 1 (Journal OF Welding Science and Technology 2025)
Abstract
This experimental-statistical study investigates the influence of laser cladding parameters—laser power (700–900 W), scanning speed (6–8 mm/s), and wire feed rate (70–80 mm/min)—on the geometric characteristics of single-pass coatings of 2507 duplex stainless steel on a VCN200 substrate. Experimental data were analyzed using Response Surface Methodology (RSM) with a three-factor, four-level design matrix. Measurements including clad width (W), height (H), penetration depth (b), wettability angle (Z), and dilution percentage (D) were obtained via ImageJ software. Results indicated that increasing laser power from 700 to 900 W led to a 14% increase in clad width (from 1417 to 1744 µm), a 33% rise in clad height (from 450 to 594 µm), a 6% increase in penetration depth (from 88 to 93 µm), and a 3% improvement in wettability angle (from 71° to 69°). In contrast, increasing scanning speed from 6 to 8 mm/s reduced clad width by 12% (from 1513 to 1787 µm), clad height by 31% (from 650 to 573 µm), and wettability angle by 15% (from 67° to 78°), while enhancing penetration depth by 4% (from 85 to 84 µm) and dilution by 19% (from 58% to 53%). Moreover, raising the wire feed rate from 70 to 80 mm/min increased clad height by 13% (from 502 to 747 µm) and wettability angle by 4% (from 75° to 78°), but decreased dilution by 19% (from 59% to 48%).
