Showing 4 results for Microstructure.
M. Sabzi, R. Kalantaripour ,
Volume 2, Issue 1 (8-2016)
Abstract
In this investigation, the effect of heat input of SMAW process on the microstructure and mechanical properties of Hadfield steel weld joints was investigated. For this purpose, 4 annealed sheets with thickness
2 mm prepared from Hadfield steel and then welding applied by SMAW process with 6.75 and 11.25 kJ/mm heat input values. The evaluation of the microstructures of welding joints was conducted by optical microscopy and the joints mechanical properties were examined by tensile, charpy impact and microhardness measuring tests. The results indicated that by increasing the heat input in the SMAW process, microstructure consisted from smaller grains, and strength and microhardness increased but impact energy was reduced.
H. Mehrabi Sharifabad, M. Hajisafari,
Volume 4, Issue 1 (8-2018)
Abstract
In this research, two different filler metals, ERNiCrMo-3 and ER309L, were used for developing different microstructure, austenite (γ) and austenite and ferrite (γ+δ) in the weld metal and fatigue properties of welded samples were evaluated in the air and sea water environments. Microstructural studies indicated a good agreement between predicted microstructures via schiffler diagram and metallographic studies. Evaluation of fatigue properties in the air and sea water environments revealed the austenitic weld metal, like base metal microstructure, improved the fatigue strength of welded samples. Fractographic studies and FESEM-EDS analysis showed more ductile fracture of welded samples by using ERNiCrMo-3, formation of more uniform and deeper dimples in the final zone of fatigue fracture, than that of welded samples by using ER309L. Furthermore, unlike dimple formation centers in welded samples by using ER309L, Mo-Ti rich intermetallics caused formation of dimples in the welded sampled via ERNiCrMo-3.
S. A. Beheshti Bafqi, M. Mosallaee,
Volume 6, Issue 2 (12-2020)
Abstract
In the present study, the transient liquid phase bonding of AISI 2205 dual phase stainless steel with amorphous BNi-3 interlayer was carried out. Based on the initial experimental and analytical studies, the parameters of temperature and bonding time were determined. In order to investigate the effect of bonding temperature on the microstructural changes of the joint, bonding was performed in the temperature range of 1050-1200℃ for 20 min. The microstructural and phase analyses indicated the completion of isothermal solidification and the formation of a uniform Ni-solid solution in the bonding zone centerline. The interdiffusion between the bonding zone and the adjacent base metal resulted in the formation of boride and nitride intermetallic compounds in the base metal adjacent to the bonding zone, which the area fraction of this intermetallics significantly decreased with increasing bonding temperature from 1050℃ to 1200℃ (reduction of the intermetallic area fraction from 85% to 40%). Evaluation of shear strength of samples showed that despite the completion of isothermal solidification in all samples and shear strength of bonded samples significantly depends of amount and morphology of intermetallic compounds on the transient liquid phase bonding shear strength. By increasing the bonding temperature to 1200℃ and reducing the area fraction of intermetallic compounds up to 40% of the shear strength of the samples increased from 450 MPa of TLP bonded specimen of 1050℃ to about 85% of base metal shear strength.
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.
