Showing 4 results for Weldability
A. Hajitabar, H. Naffakh-Moosavy,
Volume 4, Issue 2 (1-2019)
Abstract
The effect of electron beam welding current changes on the microstructure and mechanical properties of the Nb-based alloy has been investigated. The electron beam welding was applied with 4 different currents of 20, 24, 30 and 35 mA on 3mm thick plates. The aspects including different welding regions, geometry and depth of welding penetration, as well as the effect of heat input on the weldability are investigated. The mechanical properties including tensile and microhardness values of the weld was also measured. The results show that in a sample with a 30 mA welding current, the optimum conditions for the depth of penetration, weldability and the geometry of the weld are obtained. The welds showed a cellular structure, and intercellular dendrites in the central region of the weld have been caused due to microsegregations created between the cells. In HAZ, severe recrystallization and grain growth has occurred. Because of the high thermal conductivity of niobium, the HAZ size is relatively large. Based on the 3D Rosenthal’s equation, the recrystallization temperature of alloy was calculated as 713 °C. It is observed that as G × R increases, the grain size in the central line of the weld decreases. The hardness profile shows that the hardness of the weld zone and the HAZ is significantly less than that of the base metal due to elimination of work hardening effect. The tensile strength of the weld for a sample with a current of 30 mA was 281MPa, which is 53% of the tensile strength of the base metal and the weld was broken from the HAZ.
R. Ashiri, M. Shamanian, H. R. Salimijazi, Y. Park, M. R. Salmani,
Volume 6, Issue 2 (12-2020)
Abstract
Nowadays, the use of advanced high strength steels (AHSSs) in body-in-white is one of the hot applied strategies which is followed by the most of the automakers. The study of weldability and weld challenges facing these steels in resistance spot welding process as the most widely used process in the assembly lines of the automotive industry is essential to use the outstanding mechanical responses of AHSSs. This study can result in improvement of mechanical performance of the resistance spot welds of AHSSs. Our results indicate that AHSSs experiences different welding challenges which this work aims to study them by discussing their causes, mechanisms involved and potential ways to address them.
M.m. Jafari, A. Afsari, S.a. Behgozin, Sh. Heidari,
Volume 8, Issue 2 (1-2023)
Abstract
In this study, the mechanical and tribological properties of 4 different types of welding filler metals were examined on a 1.6959 steel (DIN35NiCrMoV12-5) by the Gas Tungsten Arc Welding process. The fillers used in this study include ER70S-6, ER80S-G, ER80S-Ni1, ER80S-B2. The main reasons for choosing these fillers in this study are their availability and close chemical composition to the base metal. To evaluate the weld and quality of weld joints, tensile, impact, hardness and abrasion tests performed on the samples and related microstructures was investigated by optical microscope. The results indicated that the presence of molybdenum and chromium alloying elements in ER80S-B2 filler and related microstructure at HAZ has led to an increase in weld strength up to 38 percent. The best and worst wear resistance obtained from the filler ER 80S-Ni1 and ER 70S-6 respectively. The best weld quality and mechanical properties were acquired in welding using ER 80S-B2 welding filler metal.
M.r. Borhani, S.r Shoja-Razavi, M. Erfanmanesh, F. Kermani, S.m. Barekat ,
Volume 9, Issue 1 (5-2023)
Abstract
Inconel 713LC super alloy is one of the most widely used high-temperature alloys. Due to the high level of gamma prime phase caused by Ti and Al alloy more than a critical value, this alloy is considered as one of the non-weldable alloys. One of the basic repair methods of this series of superalloys is laser cladding methods. In this research, the IN713LC substrate was reconstructed with Inconel 625 powder by a direct laser deposition system. To characterize, optical and electron microscopy tests, porosity measurement, and XRD were carried out; The results showed that the R (growth rate of the dendrite tip) increases at high speeds of laser cladding; as a result, the G/R (combined solidification point) ratio decreases, and the structure tends towards the coaxial dendritic direction. For this reason, by increasing the speed of laser scanning from 4 to 6 mm/s, the coaxial dendritic structure increases. The hardness measurement results indicate a decrease in the hardness up to the junction area from 430 to 370 Vickers and fluctuations of about 50 Vickers. Due to the high solidification speed, the average distance between the secondary dendritic arm space was 0.8 at the bottom, 1.01 in the middle, and 1.75 micrometers at the top of the sample. Due to the high cooling speed, only carbides and lava phases are formed. Also, the porosity measurement results of the cladding indicate a maximum porosity of 0.1 percent.
