Showing 74 results for Steel
M. Hajizadeh, S. Emami, T. Saeid,
Volume 6, Issue 1 (8-2020)
Abstract
Friction stir welding was conducted on AISI 304 austenitic stainless steel sheet with dimensions of
100 mm × 100 mm × 2 mm. The FSW was performed at a welding speed of 150 mm/min and rotational speeds of 400 and 800 rpm. The results showed that high frequency of low angle grain boundaries (LAGBs) were formed through dynamic recovery in the thermo-mechanically affected zone (TMAZ). Higher amount of LAGBs were developed in the TMAZ of welded sample with 800 rpm due to the higher amount of strain and heat generated. High fraction of high angle grain boundaries were formed in the stir zone (SZ) of the welded samples through the occurrence of continuous dynamic recrystallization (CDRX). A very fine microstructure developed in the sampled welded with lower rotational speed. Analysis of texture using {111} Pole figures showed the formation of shear texture components in the SZ of both welded samples. The intensity of the obtained texture for the sample welded with 800 rpm was greater. The formation of shear texture components in the SZ of both samples implied the occurrence of CDRX mechanism
A. Ghandi, M. Shamanian, M. R. Salmani3,
Volume 6, Issue 1 (8-2020)
Abstract
The structural and hardness developed in advanced high-strength steel DP590 have been investigated with the help of optical microscopy and scanning electron microscopy on resistance spot welded specimens. The hardness diagram of the weld sections was prepared by microhardness test and the temperature peak and heat distribution were simulated by menas of the Abaqus software. The results show that according to the temperature generated in each region of the weld nugget, the HAZ and base metals have different microstructures, and these difference affects the hardness of the regions. The presence of tempered martensite islands with a fraction of 44% in ferrite matrix in base metal, mainly martensitic structure in the nugget, and martensitic structure along with scattered areas of ferrite in the HAZ was observed. The results of the microhardness tests showed difference in hardness values of the regions, and also it was observed that the hardness values increased in the HAZ and weld zone. The hardness values measured in the nugget, base metal, and HAZ were around 400, 200, and 450 HV which were in accordance with the observed structures
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Volume 6, Issue 1 (8-2020)
Abstract
In this research, effect of time and temperature of TLP process on the microstructure, mechanical properties and corrosion resistance of CP-Ti to 316L stainless steel joint evaluated. For this purpose pure copper foil with 100 µm thickness was used as interlayer and joining process carried out at 950˚C, 1000˚C and 1050˚C and for 90, 120 and 150 minutes. After the joining process, shear and micro-hardness test and corrosion resistance were applied in the samples. The test results revealed that the shear strength of the sample 1000˚C is better than two other soaking temperatures. The main reason was the formation of less intermetallic compounds at the interface, as well as the presence of less athermally solidification zone area. Microstructural examinations for the sample after TLP at 950˚C revealed no iron and titanium bearing intermetallic compounds in the interface while for two other samples, there exist considerable amount of intermetallics in the microstructure. Corrosion test results showed that the resistance against corrosion depends on the intermetallic compounds formed in the interface. Intermetallic phases includes FeTi, TiCu, Ti2Cu, and TiCu2. The sample prepared at 1000˚C for 120 minutes had less intermetallic compounds and as a result, had the best corrosion resistance. Fe and Ti containing intermetallics had good corrosion resistance in simulated body fluid, as comparison with Ti and Cu containing compounds.
P. Shayanfar, H. Daneshmanesh, K. Janghorban,
Volume 6, Issue 1 (8-2020)
Abstract
In this study, the effect of overlapping percentage on microstructure and mechanical properties of a single-pass coating by Inconel 625 powder laser has been investigated for quench-tempered ASTM A592 steel. In order to have a structural analysis, the inter dendritic distance was evaluated. For this purpose, scanning electron microscopy (FESEM) and Digimizer software were adopted. In order to investigate mechanical properties, elastic modulus, toughness, and micro hardness were evaluated. For the evaluation of elastic modulus, Noop indentation method was used, and for toughness studies, Evans method was applied. After the investigation, it was found that in the overlapping of single-pass 50% coatings, the heat input value is lower than overlapping in single-pass 75% coatings. It also contains a finer structure with much higher mechanical properties. This is in such a way that the inter dendritic distance in single-pass 50% coatings is about 0.91 µm. The average diameter of the dendritic columns is about 0.32 µm, hardness value is about 10%, Knoop hardness is about 9 units, elastic modulus is about 37 GPa, and toughness is about 9 MPa m1/2 higher in comparison with the 75% overlapping case.
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.
A. Lori Amini, H. Sabet, M. Ghanbari Haghighi ,
Volume 6, Issue 2 (12-2020)
Abstract
In this investigation, the AISI 2205 duplex stainless steel was welded in the form of bead on plate by A-TIG process with different amount of the ZrO2 and TiO2 activated fluxes. The results of the visual inspection showed that the specimen with 50% ZrO2 and 50% TiO2 activated flux, had the lowest face width and the specimen with contains 90% ZrO2 activated flux, had the highest penetration depth. Also, the results showed that the angular distortion of the specimens with mix of the ZrO2 and TiO2 activated flux were 225% less than the specimen without activated flux. The results of macroscopic examination of different samples showed that the maximum length and width of the macroscopic grains were related to the sample with 90% ZrO2 activated flux and the smallest length and width of the macroscopic grains were related to the sample with 90% TiO2 activated flux. The hardness test results showed that the highest hardness of the samples was gained to 90% TiO2 activated flux specimen with 950 HV and the lowest hardness value for the sample with 90% ZrO2 activated flux with 410 HV. The results of all tests showed that surface activated fluxes (ZrO2 and TiO2) affected to the depth of penetration, face width, angular distortion, length and width of macroscopic grains and the hardness of weld metal by changing the longitudinal and transverse melt flow in the weld pool.
M. Yousefieh, A. Jabbari,
Volume 6, Issue 2 (12-2020)
Abstract
In this study, the temperature in friction stir welding of duplex stainless steel has been investigated. At first, temperature estimation was modeled and estimated at different distances from the center of the stir zone by the multivariate Lagrangian function. Then, the linear extrapolation method and multiple linear regression method were used to estimate the temperature outside the range and center of the stir zone. Temperature estimation is based on three parameters rotational speed, welding speed and distance from the center of stir zone. In the first method, by generalizing the multivariate Lagrangian method, the multivariate Lagrangian temperature function was generalized according to the above parameters. In the second method, in order to investigate the effect of the variables in the regression model, a comparison of two complete models and a reduced model based on the sum of squares errors was used. Then, by analyzing the multiple regression equations governing the output variable, a multiple linear regression function was introduced. Since the temperature of the stir zone is not measurable by the thermocouple, so in general the best fit curve for estimating the function is when the modeling is based on parameters that minimize the error function.To implement the multiple linear regression method, the error function was introduced to minimize the sum of the error squares and the error derivative was calculated in relation to the parameters of tool rotation speed, welding speed and distance from the center of the stir zone. Therefore, multiple linear regression method was considered as the basic method and as a criterion with other methods. According to the results obtained from the prediction in the center of the stir zone, the temperature difference in all three methods is desirable and negligible. The maximum temperature difference of multiple linear regression method with multivariate Lagrangian method in all nodes was 18.8 oC and multiple linear regression method with linear extrapolation method was 26.36 oC. Therefore, the multivariate Lagrangian interpolation method is less different than the linear extrapolation method in the center of the stir zone and is more accurate.
Z. Shahryari, I. Keivanrad, K. Gheisari, K. Ranjbar, R. Dehmolaei, S. R. Mousavi,
Volume 6, Issue 2 (12-2020)
Abstract
In this study, Inconel 617 alloy was welded to A387-Gr.11 low-alloy steel using ER309L filler metal via gas tungsten arc welding (GTAW). First, the corrosion behavior of Inconel 617, A387-Gr, and the weld metal was evaluated by the Tafel polarization test and electrochemical impedance spectroscopy (EIS) in acidic (H2SO4), neutral (NaCl), and combined (H2SO4 + NaCl) solution at ambient temperature. The results of polarization and EIS measurements in all corrosive solutions indicate that the corrosion resistance decreases from 617 alloy to weld metal and from weld metal to low-alloy steel, respectively. The Comparison of the polarization curves of the base metals and the weld metal showed susceptibility to galvanic corrosion between Inconel 617 / weld metal in 1M NaCl solution. The behavior of galvanic corrosion of this pair was evaluated using the mixed potential theory and the electrochemical noise measurement. The results showed that in a galvanic couple of alloy 617 / weld metal, the weld metal acts as anode and corrodes in such a way that its corrosion rate increases from 0.22 μA/cm2 before joining to 1 μA /cm2 after joining.
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.
M. Alimadadi, M. Goodarzi, S.m.a. Boutorabi,
Volume 7, Issue 1 (8-2021)
Abstract
This present study aimed to create an Al6061-St52 dissimilar joint and investigate the effect of the transverse speed by the friction stir welding process. Welding aluminum to steel is rugged by fusion methods because of the formation of brittle intermetallic compounds (IMCs). Therefore, to designate optimal parameters, acceptable IMC thickness, and mechanical properties determined. This research carried out different three transverse speeds of 16, 40 and 85 mm/min (with a constant pin offset of 0.2 mm). Geometry of tool's pin radius and height is 4mm and 1.8mm, respectively. In the transverse speed parameter, the highest ultimate tensile strength (UTS) of 200 MPa was obtained at 85 mm/min. According to the Energy Dispersive X-ray Spectroscopy results, an IMC layer formed in the joint interface. The heat input rate was calculated to designate the optimal parameters. In tensile specimens, fracture mainly occurred in the joints and within the aluminum stir zone due to the combination of thick IMC layer and steel fragments, respectively. The micro-hardness measurement results showed that at (85 mm/min) the hardness values were HV 75 in the aluminum stir zone and HV 315 in the AS vicinity of the interface region. This hardness value is much higher than the base metals (Aluminum base metal is an average of HV 53 and an average steel base metal of HV 245).
Mehdi Asle Taghipour, Reza Dehmolaei, Seyed Reza Alavi Zaree, Mohammad Reza Tavakoli Shoushtari,
Volume 7, Issue 1 (8-2021)
Abstract
The microstructure and mechanical properties of HSLA-100 steel weld joints was investigated. Welding with three heat input of 0.820, 1.176 and 1.392 kJ / mm was performed using E12018 electrode. Microstructural studies were performed using scanning electron and optical microscopes. The mechanical properties of welded joints were evaluated by impact and microhardness tests. Microstructural studies showed that with increasing the heat input, the amount of acicular ferrite in the weld metal decreased and the amount of polyhedral and quasi-polygonal ferrite increased. It was found that with increasing the heat input, the amount of layered bainite in the heat affected zone increased and the amount of granular bainite decreased. Due to the decrease in the amount of acicular ferrite in the weld metal microstructure with increasing inlet temperature, the amount of hardness and impact energy decreased. The results showed that the increase in heat input due to the reduction of the acicular ferrite of the weld metal and the dissolution of precipitates in the coarse grain heat affected zone has caused a decrease in hardness in these zones. It was found that with increasing the heat input due to decreasing the acicular ferrite, the impact energy of the weld metal decreased by 29% (from 45 joules at an heat input of 0.82 to 32 joules at an heat input of 1.392 kJ / mm). It was found that at all heat inputs, the impact energy of the base metal is greater than the impact energy of the weld metal.
Hossein Tahmasebi Manesh, Alireza Nasresfahani, Alireza Nasresfahani,
Volume 7, Issue 1 (8-2021)
Abstract
One of the applications of P460NH micro-alloy steel is its use in pressure vessel tanks. Electrode E8018-G can be used for welding this steel. In this study, to obtain the optimal welding parameters, the arc process based on ASME IX standard was used. Then, by sampling from the weld section, Vickers hardness test was performed and hardness profiles were drawn in different areas. Then the microstructure of each area was examined and compared with the hardness test results. The corrosion behavior of the heat affected zone, weld zone and base metal was investigated separately using the TOEFL polarization test in a 3.5% solution of NaCl. The results showed that the weld zone had the highest percentage of perlite (62%) and the base metal had the highest percentage of ferrite (73%). Also, the heat affected zone has the highest hardness number (298) and the base metal has the lowest value (210) in the Vickers scale. Evaluation of corrosion behavior of different areas also showed that the heat affected zone has the highest corrosion potential (-.651v) and the lowest corrosion current density (1.75×10-5 A/cm2). This is while the base metal has the lowest corrosion potential (-.691v) and the highest corrosion current density (1.2×10-6 A/cm2) compared to the weld metal and the heat affected zone.
Dr. Mohammad Yousefieh,
Volume 7, Issue 1 (8-2021)
Abstract
In this paper, using the Taguchi method, the parameters affecting the toughness of super duplex stainless steels in friction stir welding were optimized. In order to achieve optimal conditions, maximum toughness, the quality characteristic was used as the higher the better. Analysis of Taguchi results showed that in order to achieve optimal conditions in super duplex stainless steel weldments must have a tool rotational speed of 500 rpm, a welding speed of 60 mm / min, an initial pressure of 70 MPa and a tool tilt angle with the workpiece is equal to 3 degrees. Under optimal conditions, the toughness obtained from the confirmation test was 61 J, which was very close to the predicted toughness (58 J). Analysis of variance was also performed on the results of signal to noise (S/N) ratio. According to the results of analysis of variance, the tool rotational speed parameter with an influence percentage of 64% was the most effective parameter on toughness in friction stir welding of super duplex stainless steels. On the other hand, the parameters of welding speed (with an influence percentage of 17 %), initial 2 pressure (with an influence percentage of 16%) and tool tilt angle to the workpiece (with an influence percentage of 3%) were in the next ranks. Also, SEM micrographs from fracture surface of the samples in the impact test proved that the sample that had the least toughness in the impact test had a cleavage morphology and as a result, brittle fracture. This was while the morphology of the fracture surface of the tested sample under optimal conditions (with the highest toughness in this study = 61 J) had a large amount of fine and deep dimples. The presence of these dimples in large quantities indicated ductile fracture and eventually reaching the highest toughness.
H. Sabet, R. Tahavori, A. Alimoradi,
Volume 7, Issue 2 (1-2022)
Abstract
Effect of Interlayer Composition on the Microstructure and Mechanical Properties of 1050 Aluminium to St14 Carbon Steel Joint Via Resistance Spot Welding Method.
Behrooz Beidokhti, Amin Ghorbani,
Volume 7, Issue 2 (1-2022)
Abstract
The present study investigated the effect of electrode composition and buffer layer on the microstructure and mechanical properties of H13 tool steel repair welds. Three specimens were welded applying two conditions; i.e. with and without stainless steel underlay. The microstructure of all weld metals contained the martensitic matrix with distributed chromium carbide precipitations. The microstructure of the underlay was a mixture of austenite and layers of ferrite with the skeletal morphology. The results showed that hardness of the welded substrates with underlay was higher than that of the specimens without underlay. This difference could be more than 240 HV. However, the highest hardness values were obtained in the heat affected zone of welds. The application of tough underlay improved the weld toughness and bending properties of the welded specimens. Also, it encouraged the ductile fracture mode in weldments. Also, the higher hardness of weld metal could be resulted from the application of buffer layer.
M.h. Zakeri, A.r. Nasresfahani, S.m. Barekat,
Volume 7, Issue 2 (1-2022)
Abstract
In this research, the microstructure of Inconel 625 cladded layer on ASTM A575 steel has been investigated. By examining different parameters, the optimal single-pass sample with the least amount of dilution, porosity and fusion and suitable wetting angle was determined. Then cladding process with the optimal parameter was performed. The microstructure of the cladding layer was evaluated from the base metal to the top. Due to different cooling rates, dendritic morphologies were observed at different distances. Also, the cladding layer was free of any cavities, porosity and cracks and its thickness was 0.9 mm (900 micrometers). The results of (XRD) and (EDS) analyzes indicate thatthe γphase is formed and there is a relatively uniform distribution of elements in the cladding layer. These results also indicate that no change in the chemical composition of the substrate surface was achieved near the interface.The hardness test results also show that the hardness starts from 450 VHN at the top surface and reaches to 135 VHN in the base metal with a gentle slope. This slope of hardness can be attributed to the cooling or heating rates of the substrate.
Dr Behzad Binesh, Dr Sima Mirzaei, Mr Amin Taghi-Ahari,
Volume 7, Issue 2 (1-2022)
Abstract
Transient liquid phase (TLP) bonding of AISI 304L stainless steel was carried out using BNi-2 amorphous interlayer. The microstructure of the joint area was studied by using optical and scanning electron microscopes and energy dispersive spectroscopy. The effect of bonding temperature (1030-1110 °C) was studied on the microstructure and corrosion behavior of the TLP bonded samples. Electrochemical corrosion resistance of the bonded samples was evaluated in 3.5% NaCl solution at room temperature. The mechanism of the microstructure formation and the solidification sequence at the joint area were discussed. Ni- and Cr-rich borides, Ni-Si-B compound and fine Ni3Si particles were identified in the γ-Ni matrix at the joint centerline. The microstructural investigations revealed that the solidification sequence of these phases is: L→ γ + L → γ + Ni boride + Cr boride + L → γ + Ni boride + Cr boride + Ni-Si-B Compound. The highest corrosion resistance was observed in the sample bonded at 1070 °C for 30 min, which is comparable to that of the as-received AISI 304L stainless steel. It was attributed to the bond region microstructure with a negligible amount of eutectic constituents formed in the athermally solidified zone.
M. Vatandoost, E. Mohammadi Zahrani, B. Beidokhti, A. Davoodi,
Volume 8, Issue 1 (8-2022)
Abstract
The welding joints were investigated due to the significance of similar welding of Corten A weathering steel and its dissimilar welding with St12 plain carbon steel in industrial applications. The gas metal arc welding (GMAW) technique with carbon dioxide shielding gas was utilized in the present work. The welding process comprised current and voltage control, welding wire injection rate, shielding gas rate, welding speed, connection configuration, and microstructure evolution. Mechanical properties and microstructure evolution in similar and dissimilar joints and weld defects were evaluated by tensile, bending, hardness, metallographic, and radiographic tests. The weld microstructure in similar and dissimilar joints included grain boundary ferrite, acicular ferrite, and WidmanStatten ferrite. The tensile strengths of the similar and dissimilar joints were respectively 497 and 303 MPa. The weld zone hardness was 210 and 180 Vickers for similar and dissimilar joints, respectively. In conclusion, similar welding outperformed dissimilar welding considering weld joint defects, mechanical properties, and microstructure.
H. Gorji, Dr. S. M. Barakat, S. R. Shoja Razavi, S. S. Babaie Sangetabi, M. Erfanmanesh,
Volume 8, Issue 1 (8-2022)
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.
S. Golestanehzadeh, Dr. S.h. Mousavi Anijdan, Dr. H.r. Najafi Dezdeh Monfared,
Volume 8, Issue 1 (8-2022)
Abstract
In this investigation the effect of oxides powders of SiO2, MoO3 and CuO on the depth of penetration, microstructure and hardness profile of GTAWeld precipitation hardening martensitic 17-4PH was assessed. Samples were taken from 17-4PH steel sheet with the dimensions of 150*50 mm and with the thickness of 5 mm, and were welded by oxide powder of SiO2, MoO3 and CuO. Results showed that using oxide powder increased the penetration depth of the welded joints by about 150 percent compared to the normal condition. Also, it was shown that although using SiO2 powder increased the penetration depth to about 7.49 mm, it provides inferior weld bead appearance. The use of MoO3 and CuO powder increased the penetration depth of the weld to about 5.3 mm. Although inclusions were found throughout the side of the weld bead when MoO3 powder was employed for welding. The microstructure of the weld in different samples did not vary and included dendritic structure with delta ferrite located between the dendrites. The hardness profile of the welded joints showed the closeness of the hardness of the welded joints using different oxide powder with the base metal.
