Showing 41 results for Mechanical Properties
A. Abdollahzadeh, A. Shokuhfar,
Volume 5, Issue 1 (9-2019)
Abstract
In this study, friction stir butt welding of Mg and Al alloys with applying Zn interlayer was performed. To obtain optimum condition, a combination of two travel and three rotation speeds were selected. Mg-Zn and Mg-Al-Zn IMCs, Al solid solution and residual Zn, were the most common phases in the stirred zone, which eliminated the formation of Al-Mg intermetallics. The maximum mechanical properties were achieved for the joint fabricated at 35 mm/min and 600 rpm, caused to 24% improvement in tensile strength and around 3 times enhancement of elongation compared with Zn free sample FSWed at the same conditions. The fracture micrographs were consistent with corresponding ductility results. Fracture surfaces of Zn-added samples presented a fine texture with a mixture of brittle and ductile fracture feature, which was different from the coarse cleavage plane and fully brittle fracture of the joint without Zn interlayer.
Dr. Seyedeh Zahra Anvari, Mr. Mohammad Reza Elahi,
Volume 5, Issue 2 (1-2020)
Abstract
Magnesium alloys are very attractive materials owing to their properties of low density, high specific strength and stiffness, good castability, and weldability. AZ31 magnesium alloys in terms of weldability has better situation than the other, so it has more applications than other magnesium alloys. In this study, TIG and pulsed TIG welding method was used to welding the AZ31 alloy and finally microstructure and mechanical properties of welds with metallography, scanning electron microscopy (SEM), tensile test were examined. The results showed that the heat input affected the size of grains that are leading to changes in mechanical properties. Sample was welded with TIG welding with minimum current has maximum strength among the samples both pulsed TIG welding and TIG method. It is observed that with increasing frequency in TIG welding, strength is reduced. Despite the same IP and IB, higher frequency has created a stronger welding. Also increases the frequency leads to more fine-grained samples, resulting in increased strength.
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.
H. Ebrahimzadeh, H. Farhangi,
Volume 6, Issue 2 (12-2020)
Abstract
The non-continuous laser beam in pulsed lasers allows the mechanical peening between two consecutive beams on a still hot weld bead. At a very short time (20, 150 and 300 ms) after laser pulse application, mechanical peening was performed on the welding bead. To achieve these short times, the light sensor detects the nth laser pulse and the mechanical arm starts moving. Upon reaching the tip of the pin near the workpiece, the n + 1th pulse was irradiated to the workpiece surface, and so the pin impact to the weld bead after traveling a short distance. Desirable mechanical properties were obtained at the highest time (300 ms) and highest pressure (6 bars). In this time and pressure the weld beads were not broken due to bending forces of peening.
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).
Hosseinn Soleimani, Kamran Amini, Farhad Gharavi,
Volume 7, Issue 2 (1-2022)
Abstract
In this research, butt joining of Al2024 and Al7075 plates were performed by Friction Stir Welding (FSW) and the effect of tool position on microstructural and mechanical properties in about 1 mm from center line of joint towards the advancing side (AS) and the retreating side (RS) was investigated at three positions of +1, 0, -1 mm. In this regard, the plates of Al2024 and Al7075 were selected as the AS and the RS, respectively. In this joining method, transvers speed of 200 mm/min and tool rotation speed of 600 rpm were chosen. Macro- and Micro- structures of various welding areas and fractography of samples were evaluated by optical and scanning electron microscopies. In addition, mechanical properties were investigated using micro-hardness and tension tests. From the obtained macro-structures, it was observed that in all three joints, the surface of weld was without any defects (i.e., porosity, lack of penetration…). With varying tool offset position, welding micro-structure morphology was changed from homogeneous mode to layer or onion ring- shaped mode. Moreover, with varying tool position into the AS-side, tensile strength increased about 17.5% as opposed to the zero-tool position, but there was a decreasing about in tensile strength with changing tool position towards the RS-side as compared with the zero-tool position. Value of micro-hardness was approximately similar in all welded samples, but the highest value of hardness was observed at the weld zone (WZ). Thus, the obtained results showed that with varying tool position into the AS-side, mechanical properties were improved as opposed to the zero-tool position and tool position towards the RS-side.
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.
S.e. Moosavi, M. Movahedi, M. Kazeminezhad,
Volume 8, Issue 1 (8-2022)
Abstract
In this study, thermo-mechanical stability of two-pass constrained groove pressing (CGP) AA1050 sheets towards friction stir welding (FSW) employing hybrid powder (%50vol. micrometric graphite powder+%50vol. α-Al2O3 nanoparticles) was investigated by examining its microstructural evolutions and mechanical properties. FSW was carried out via different process variables in order to reach the highest ultimate mechanical properties of joints. The welding variables employed in this study were single-pass and multi-pass FSW, and different rotation speed to traverse speed ratios (ω/v) were. In order to appraise the powder effect on mechanical properties in the fabricated hybrid metal matrix composite (HMMC), some CGPed sheets were also welded with no powder. Besides optical microscopy and field emission scanning electron microscopy (FESEM) observations, Vickers microhardness and transverse tensile tests were conducted to examine mechanical properties of the weld zone. It was revealed that the effect of graphite powder as a solid lubricant was substantially influenced by the welding variables. More precisely, by employing graphite powder during the FSW, the peak temperature decreased to 224 ℃, while the peak temperature of 489 ℃ was resulted by welding without any powder. Thus, the thermo-mechanical stability of CGPed aluminum and their mechanical properties were enhanced. On the other hand, graphite powder can be responsible for mechanical properties drop due to deteriorating material flow. In addition, different strengthening mechanisms, including grain boundary Zener-pinning and particulate stimulated nucleation (PSN) mechanism, were provided and governed by both powders. However, increasing the ω/v ratio was a practical approach to obtain uniform powder distribution, and consequently, to attain ultimate mechanical properties. Moreover, weld soundness was perceived to be achievable by increasing the number of FSW passes due to eliminating the cavities and improved material flow, resulting in an ultimate tensile strength of 101 MPa, as an optimum efficiency of ~ %80, in three-pass FSW at ω/v=70.
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.
S. Kazemi, G. Khalaf, A. Afsari, M.j. Marzban,
Volume 8, Issue 2 (1-2023)
Abstract
Stainless steel cladding is the formation of an alloy by creating a thin layer of stainless steel on another metal. In this research, a layer of SA240-TP316 austenitic stainless steel was coated on SA516-GR60 steel. Experiments were conducted to compare the mechanical properties of SA240-TP316 and claded SA516-GR60 steel welds in order to investigate the possibility of replacing the SA240-TP316 steel alloy. Examining the results of the chemical analysis of SA240-TP316 alloy shows that the coating has a similar chemical composition to SA240 alloy and with increasing depth, the hardness of the weld metal and the percentage of chromium is higher and the percentage of molybdenum in the weld alloy is lower. Comparing the ultimate strength of SA516 alloy after cladding and welding with SA240 stainless base alloy shows the improvement of tensile strength. In the first case, the strength changes in the range of 470 to 503 MPa and in the second case in the range of 477 to 570 MPa. The highest hardness was obtained in the heat affected area. Bending test showed that bending without cracking up to 180 degree angle is a sign of weld metal remaining ductile. The results of the impact test also show the ability to absorb energy, especially around the voltage of 150 volts.
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.
A. Mahdavi Shaker, H. Momeni, A. Khorram, A. Yazdipour,
Volume 8, Issue 2 (1-2023)
Abstract
This study aimed to investigate the effect of electron beam welding parameters on the microstructural characteristics and mechanical properties of the dissimilar joint between 17-4PH precipitation hardening stainless steel and Ti6Al4V alloy. For this purpose, the welding of these two alloys was done without an interlayer and with an interlayer of copper with a thickness of 0.8 mm. Two different welding speeds of 0.7 and 0.9 m/min with four levels of beam offset (0, 0.2, 0.4 and 0.6 mm) from the center of the interlayer towards the steel were used to perform experiments. The results show that in the direct welding of titanium and steel, the joint structure consists of TiFe and TiFe2+TiCr2 intermetallic compounds with high hardness (about 900 Vickers). In the welding of titanium and steel by using the copper interlayer, the structure in the weld pool and the interface between the weld pool and steel includes a solid solution of copper and TiFe2 intermetallic compounds, and at the interface between the weld pool and titanium includes Ti+Ti2Cu and TiFe. The hardness of the welding zone in the samples welded with copper interlayer is about 400 Vickers. The highest value of hardness is observed at the interface between the weld pool and titanium alloy, as well as at the interface between the weld pool and steel, which is due to the presence of intermetallic compounds with high hardness. By increasing the welding speed and beam offset, the hardness decreases, which is due to the reduction of brittle intermetallic compounds in the joint structure. The welded sample with a welding speed of 0.9 m/min and beam offset of 0.6 mm has the highest shear strength equal to 160 MPa.
A. Mahdavi Shaker, H. Momeni, A. Khorram, A. Yazdipour,
Volume 9, Issue 1 (5-2023)
Abstract
This study aimed to investigate the effect of electron beam welding parameters on the microstructural characteristics and mechanical properties of the dissimilar joint between 17-4PH stainless steel and Ti6Al4V alloy. For this purpose, the welding of these two alloys was performed with an copper interlayer with a thickness of 1 mm. Two different welding speeds of 0.7 and 0.9 m/min with four levels of beam offset (0, 0.2, 0.4 and 0.6 mm) from the center of the interlayer towards the steel were used to accomplish the experiments. The results show that by using the copper interlayer with thickness of 1 mm, the cracks caused by the formation of intermetallic compounds are removed from the weld pool. At the interface between the titanium and the weld pool, at the beam offset of 0 and 0.2 mm, a solid solution of copper and TiCu2 intermetallic compounds is formed, while at the beam offset of 0.4 and 0.6 mm, a solid solution of copper and TiCu intermetallic compounds is formed. The weld pool, at the beam offset of 0 and 0.2 mm, consists of TiCr2+TiFe2 intermetallic compounds while at the beam offset of 0.4 and 0.6 mm, solid solution of iron (α-Fe), solid solution of copper and TiCu intermetallic compounds are formed. The highest value of hardness is observed at the interface between the weld pool and the titanium alloy, as well as at the interface between the weld pool and the steel, which is due to the presence of intermetallic compounds with high hardness in these regions. By increasing the welding speed and the beam offset, the hardness value decreases, which is due to the reduction of brittle intermetallic compounds in the joint structure. By increasing the beam offset from 0.4 mm to 0.6 mm at the speed of 0.7 m/min, the shear strength increases from 180 MPa to 210 MPa and at the speed of 0.9 m/min, the shear strength raises from 230 MPa to 250 MPa. The welded sample with the welding speed of 0.9 m/min and the beam offset of 0.6 mm has the highest shear strength equal to 250 MPa. The failure in all samples happened at the interface between the weld pool and the titanium alloy, which shows that the weakest region in the joint is this interface.
M. Ahmadi, H.r. Ahmadi, M.r. Khanzadeh, H. Bakhtiari,
Volume 9, Issue 1 (5-2023)
Abstract
In this research, friction stir welding of aluminum 1050 to copper with variable speed was investigated. For friction stir welding, rotational speeds of 900 and 1200 rpm and traverse speeds of 36, 63, and 125 mm/min were used. In order to check the phases and microstructure, scanning electron microscope analysis, X-ray spectrometry, and hardness testing were used. The disturbance zone included Al2Cu3, Al4Cu9, AlCu4, Al2Cu, and AlCu phases. The results showed that the formation of intermetallic phases and severe plastic deformation in the welding area caused an increase in hardness. The highest hardness value in the stirred area was 97.8 Vickers at a rotation speed of 900 rpm and an advance speed of 36 mm/min.
Dr. Mojtaba Movahedi, Hosseinali Shirovi Khoozani, Ashkaan Ozlati,
Volume 9, Issue 2 (8-2024)
Abstract
Ms Majid Rahimi, Dr. Mahdi Omidi, Dr. Saeid Jabbarzare, Dr Hamid Reza Bakhsheshi-Rad, Dr. Masoud Kasiri-Asgarani, Dr. Hamid Ghayour,
Volume 9, Issue 2 (8-2024)
Abstract
In this research, copper/silver-silicon carbide Cu-Ag-SiC composite was prepared by the friction stir processing (FSP). For this purpose, nanometer and micrometer SiC particles were used as reinforcing particles. In order to evaluate the microstructural properties, X-ray diffraction (XRD) analysis, scanning electron microscope and optical microscope were employed. Evaluation of mechanical properties through microhardness measurement, tensile test and pin on disc test were utilized to evaluate the wear behavior of the composite. The results of X-ray analysis revealed the presence of two phases of CuAg solid solution along with SiC particles, which indicated the formation of Cu-Ag-SiC composite. The addition of nano-particles led to a significant decrease in the intensity of peaks compared to micro-particles. This indicated a decrease in the grain size of the CuAg matrix. Using the FSP in the presence of reinforcing particles and without it led to a decrease in the crystal size and average grain size compared to the sample without FSP. So that the grain size of the sample without FSP and the FSPed sample without reinforcing particles and with nano-reinforcing particles were found to be about 46.3, 19.2 and 3.6 µm, respectively. The wear mechanism in the sample before FSP was adhesive wear due to its soft nature of the matrix, and after FSP in the sample without reinforcing particles, the adhesive wear decreased and due to the addition of silicon carbide micro and nano- particles reinforcement, the wear mechanism in entirely altered to abrasive wear. Overall, it can be stated that the addition of silicon carbide nanoparticles by FSP leads to the fabrication of Cu-Ag-SiC composite with high mechanical properties.
M.r. Hajiha, A. Farzadi, S. A. Samadani Agdam, A. Shabanzadeh, S. Ramezani,
Volume 9, Issue 2 (1-2024)
Abstract
5xxx and 6xxx series alloys are among the most widely used aluminum alloys in various industries, including automobile, shipbuilding and aviation industries. In this research, the joint of two alloys AA6061-T6 and AA5052-H12 was investigated at 4 transmission speeds of 60, 90, 120 and 180 mm/min and 3 rotation speeds of 600, 800 and 1000 rpm. These investigations were carried out in the condition that each of the two alloys was placed in two progressive and regressive sides. The results of these studies showed that the highest tensile strength is when the AA5052 sample is placed on the advancing side and the transfer speed is 90 mm/min and the rotation speed is 600 rpm, and in this case, the final tensile strength value is equal to 197 MPa. In addition, the results showed that, generally, the tensile strength decreases with an increase in the transmission speed at a constant rotational speed, and with an increase in the rotational speed at a constant transmission speed, the tensile strength increases. In addition, microscopic and macroscopic examination of the sections of all samples was performed and various areas and defects were examined. According to the investigations carried out on the microstructure, the grain size in the weld nugget compared to the base metal, HAZ and TMAZ decreases. The grain size in HAZ is the largest in all samples, and this causes a decrease in weld strength in this zone.
A. Ardalani, H. Naffakh-Moosavy,
Volume 9, Issue 2 (1-2024)
Abstract
In this research, the effect of temperature and time parameters are investigated on the microstructure and mechanical properties of dissimilar brazing of 17-4 PH stainless steel and Ti-6Al-4V alloy with BNi-2 filler metal. The microstructure of the joint is evaluated with optical and scanning electron microscopes and the mechanical properties of the joint are also evaluated with tensile-shear and microhardness tests. It can be seen that at a constant temperature of 1050°C, increasing the time from 15 to 30 minutes decreases the shear strength from 34.66 to 29.39 MPa. Formation of brittle intermetallic compounds like NiTi2 and FeTi2 increase strength and promote brittle fracture.At a fixed time of 15 minutes, increasing the temperature from 1050 to 1100 °C causes the strength to increase from 34.66 to 38.46 MPa. Also, the increase in temperature and time increases the ISZ thickness formed in the joints on the side of the filler metal - Ti-6Al-4V from 41.40 to 81.48 microns. The increase in temperature and time also causes more diffusion of boron into the SS-filler joint, which forms various boron compounds and widens this region.
M.r Borhani, S.r. Shoja-Razavi, F. Kermani,
Volume 10, Issue 1 (6-2024)
Abstract
In this study, the effects of friction stir welding (FSW) parameters on the properties of dissimilar joints formed between 5083 aluminum alloys and 316L austenitic stainless steel, with a thickness of 4 mm, are investigated. The tool speed is varied in the range of 16 to 25 mm/min, while the tool rotation speed is maintained at a constant value of 250 rpm. To examine the microstructure of different weld regions, both optical and scanning electron microscopes are employed. To assess the mechanical properties, hardness and tensile tests are conducted. The results shows the formation of a composite region characterized by steel reinforcement particles dispersed within an aluminum matrix. At the steel-aluminum interface, a single layer of discontinuous intermetallic composition with a thickness of approximately 2 micrometers is observed. Notably, when the rotation speed is set to 250 rpm and the tool speed is 16 mm/min, a tensile strength of 298 MPa and ductility of 26% (93% of the tensile strength and 50% of the ductility of the 5083 aluminum alloy) are achieved.
R. Abbasi, S. A.a. Akbari Mousavi, Y. Vahidshad,
Volume 10, Issue 1 (6-2024)
Abstract
The present study focuses on optimizing the mechanical properties and microstructure of laser welding in Haynes 25 (L-605) cobalt-based superalloy. Initially, the influence of laser welding variables such as laser power, pulse frequency, welding speed, and pulse width on the mechanical and metallurgical properties of the weld joints is investigated. By examining the welding variables, the values of G (thermal gradient) and R (cooling rate) are calculated, and their ratio (G/R) and cooling rate (G×R), which predominantly affect the solidification microstructure, are determined. The structural correlation with the mechanical properties resulting from welding is examined. In this research, it is considered to obtain the welding variables to create a high percentage of the structure in the form of equiaxed dendrite. Microstructural analysis reveals the growth of equiaxed grains and dendritic structures in the weld zone. The high cooling rate in the weld pool leads to dendritic solidification starting from columnar dendrites at the weld walls and ending in equiaxed dendrites at the center of the weld. The microhardness value in the weld zone is HV 328, which is very close to the microhardness of the base material. The tensile strength of the weld samples reaches about 93% to 94% of the base metal tensile strength. Tensile testing of the weld samples indicates a ductile-brittle fracture. Examination of the scanning electron microscope confirms the presence of dimples, intergranular cracks, and microvoids in the fracture zone.
