Showing 9 results for Diffusion
S. Ghaderi, F. Karimzadeh, A. Ashrafi,
Volume 5, Issue 2 (1-2020)
Abstract
In the present study, the effect of time and base metal microstructure on the Transient Liquid Phase (TLP) bonding of 304L stainless steel was studied. TLP was performed at 1050 0C for 5 and 60 minutes on the coarse grain austenitic and martensitic microstructure using BNi-2 interlayer. To prepare martensitic microstructure, as-received 304L was rolled at -15 0C up to 80% rolling reduction. TEM analysis was proved that the microstructure of 80% rolled samples consisted of two different morphologies of martensite namely as lath-type and dislocation cell type martensite. It was observed that the structure of bonded zone after 5 min has consisted of isothermally solidified zone (ISZ) containing γ solid solution and athermally solidified zone (ASZ) containing complex boride phases. Meanwhile, after 60 min of heating, the structure of bonded zone completely solidifies isothermally. The obtained results also showed that the martensitic microstructure considerably effect on the width of diffusion affected zone (DAZ) which was related to the reversion of martensite to ultrafine grain austenite during heating.
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.
S. Z. Anvari, S. Daneshpour , S. Oshaghi,
Volume 6, Issue 2 (12-2020)
Abstract
In this study, diffusion bonding between titanium and AISI 304 austenitic stainless steel by Ag interlayer was investigated. In order to carry out this research, samples prepared after surface preparation were placed inside the fixture and placed at the temperatures of 750,800 and 850 °C in the 30,60 and 90 min in the furnace under argon protective gas. The phase transformation and microstructure of diffusion bonding interfaces of the joints were studied using optical microscopy, scanning electron microscopy and x-ray diffraction. Then, the hardness of the samples was measured using a hardness test apparatus. Finally, the samples were tested after being placed in the shear strength test holder using a pressure test device and the shear strength of the samples was measured. Examination of optical microscopic images shows the diffusion of silver in titanium and the partial diffusion of silver in stainless steel. On the other hand, increasing the temperature increases the diffusion region as well as increasing the grain size in the specimens. SEM images from the samples also confirmed the diffusion of silver in titanium and partially diffusion into stainless steel. The results of the XRD test on the samples showed that the temperature rise to 800 °C leads to the formation of TiAg and Ag3Fe2 intermetallic compounds, which the existence of TiAg intermetallic compound increases the hardness of the sample. For this reason, the sample at 800 °C showed the highest hardness. The shear strength of the samples showed that the increase in temperature increased the shear strength of the samples and decreased the shear strength by increasing the temperature above 850 ° C due to the formation of brittle intermetallic compounds.
H.r. Masoumi, H. Razavi, A.h. Meysami, M. Khodaei,
Volume 7, Issue 1 (8-2021)
Abstract
The aluminum alloys of Al1050 with thickness of one millimeter and Al3105 with thickness of half millimeter were joined via ultrasonic spot welding (USW). To create a suitable welding, a vibrating horn (welding tool) fit to transducer and ultrasonic generator was designed using ANSYS software. Due to mechanical and thermal cycles during USW, both diffusion and mechanical mixing facilitated the formation of welded interfaces. The alloying element, Mn, in Al3105 diffused into Al1050 during USW, and diffusion behavior varied with selection of top sheet. The fracture mechanism during lap shear testing, i.e. debonding or pullout fracture, varied based on welding power, time and pressure of jack. The optimal point for the existing welding conditions was obtained. The best welding conditions were for 750 W at 2 and 3 seconds when the horn was held on the overlap of the sheets. Also, in the tensile test, sheet rupture was performed around the welding spot (out of welding spot).
A. Anbarzadeh, H. Sabet, A.r. Geranmayeh,
Volume 8, Issue 1 (8-2022)
Abstract
In this study, to bond AA2024 and AA6061 alloys to each other, three elements (Sn, Zn and Ga) were considered as interlayer elements in terms of atomic diffusion depth in the base metal and storage at 453°C for 2 days, 10 hours, 210 minutes, and 30 seconds that they were examined for atomic diffusion modeling. Finally, the two alloys were connected at a temperature of 453°C in a furnace environment under a vacuum of 7.5×10-13 Torr under a transient liquid phase process. The effect of changing the thickness of the interlayer on the connection of the two alloys are examined with practical tests such as metallography, SEM, the distribution map of the elements, hardness test, the linear scan of the elements at the joint, and tensile strength test in two modes, 1: investigating the effect of changing the thickness of the interlayer on strength, and 2: investigating the change in joint strength by increasing sample retention time in the furnace. As the thickness of the interlayer increases (from 20 to 70 μm), the bond strength decreases. The maximum tensile strength of joint with the 20 μm thickness Sn-5.3Ag-4.6Bi interlayer is 52 MPa.
I. Saydi, R. Dehmolaei, Kh. Ranjbar,
Volume 8, Issue 1 (8-2022)
Abstract
In this research, the diffusion bonding of the stabilized zirconia ceramic and Nimonic 105 superalloy using Ti/Nb/Ni multi-interlayer was carried out. Joint was performed using the plasma spark technique in a vacuum atmosphere and at different temperatures and times. The microstructure of the different joint zones was studied using optical and FESEM microscopes equipped with an EDS analyzer. The results showed that the critical region is Ti/3YSZ interface and in all conditions diffusion bonding in Ti/Nb, Nb/Ni, and Ni/NI 105 interfaces were done. Microstructural observations showed that in the Ti/3YSZ interface at all temperature and time conditions, the connection of two separate regions including Ti3O and (Zr, Ti)2O was formed due to the difference in the diffusion depth of Ti, Zr, and O elements and with increasing temperature and time, the thickness of these regions increased. Microstructural studies showed that the bond at 900 ℃ and 30 minutes did not have any cracks and discontinuities and due to the better diffusion of atoms, a suitable reaction layer was formed. Microhardness observations and EDS analyses confirmed that the Ti3O reaction layer is the weakest zine.
A. Pourjafar, R. Dehmolaei, R. Alavi Zaree, Kh. Ranjbar, M.r. Tavakoli Shoushtari,
Volume 8, Issue 2 (1-2023)
Abstract
In this study, the effect of temperature on the microstructure and reactive layer at the interface between the Ti interlayer and the base metal related to the diffusion bonding of Zr702 to A516 low alloy steel was investigated. The joining was done using the spark plasma sintering technique at temperatures of 900, 950 and 1000°C for 30 minutes. Field Emission Scanning Electron Microscope (FESEM) equipped with EDS analysis was used to investigate the microstructure of the interfaces in various joints. Investigations showed that at all temperatures, with the diffusion of atoms and the formation of a reactive layer between the Ti interlayer and Zr702, no intermetallic phases, cracks, porosity and discontinuities were formed at their interfaces. . It was found that increasing the bonding temperature did not cause the formation of new phases and compounds in the interface and only increased the thickness of the reaction layer. The measurement of the thickness of the reactive layer showed that the maximum and minimum amounts of diffusion were 84 microns at 1000 °C and 64 microns at 900 °C respectively
A. Khorram, H. Habibi, A. Yazdipour ,
Volume 10, Issue 1 (6-2024)
Abstract
This study aimed to investigate the effect of diffusion welding parameters on the microstructural characteristics and mechanical properties of the dissimilar joint between AISI 418 stainless steel and Inconel 738 superalloy using Ni interlayer with a thickness of 50 µm. The experiments were performed in a vacuum furnace at three temperatures of 1000, 1050 and 1150 °C for 45, 60, 75 and 90 min under the pressure of 5 MPa.The results show that voids and non-bonded areas are seen in the samples that were bonded at a lower temperature (1000 °C). By increasing the joining temperature from 1000 °C to 1050 °C, all micro discontinuities have disappeared, which shows that the microplastic deformation of roughness has improved. Then, by increasing the temperature to 1150 °C,non-bonded areas are observed in the joint due to the reduction of pressure on the contact surfaces. When pure nickel is used as an interlayer, intermetallic compounds of
γ' [Ni3(Al, Ti)] are formed in the γ matrix phase on the side of Inconel 738 superalloy while compounds of FeNi3 and γ (γFe, Ni) are formed on the side of AISI 418 stainless steel. According to the results of line scan analysis, the slope and penetration of elements in Inconel 738 superalloy is lower than AISI 418 stainless steel , which indicates less penetration in Inconel 738 superalloy. In the sample welded at the temperature of 1050 °C and the time of 90 Min, the penetration value of the nickel interlayer in AISI 418 stainless steel and Inconel 738 superalloy was 40 µm and 35 µm, respectively. By comparing the maximum hardness, it can be concluded that the joint at the temperature of 1050 °C and the time of 90 Min has a lower maximum hardness than other samples. Therefore, it has better joint characteristics than other samples in terms of intermetallic compounds. The highest value of shear strength was obtained at the temperature of 1050 °C and the time of 90 Min, which is equal to 270 MPa.
Gh. Khalaj, J. Khalaj, F. Soleymani,
Volume 10, Issue 1 (6-2024)
Abstract
In this study, the microstructure of the joint interface in three-layer explosive welding of austenitic stainless steel 321 - aluminum 1050 - aluminum 5083 was examined before and after heat treatment. The welded samples were subjected to heat treatment at temperatures of 250°C and 350°C for durations of 1000, 3000, and 10000 seconds. Microstructural analysis was performed using optical microscopy and scanning electron microscopy. The results revealed that under all conditions, the Joint Interface of aluminum 5083 - aluminum 1050 exhibited a flat and defect-free structure. With increasing standoff distance, the Joint Interface of stainless steel 321 - aluminum 1050 transitioned from a smooth to a wavy pattern, and the average layer thickness increased from 4.95 μm to 6.7 μm. During heat treatment, the layer thickness in the Joint Interface increased proportionally to the diffusion kinetics, reaching maximum values of 18.56 μm and 15.02 μm for samples with standoff distances of 6.75 mm and 6 mm, respectively. The activation energies for diffusion were calculated as 46.6 kJ/mol and 42.4 kJ/mol, and the diffusion constants were 142.2 ms-1 and 45.3 ms-1 for the same samples.
