Showing 76 results for Steel
M. Sabzi, S. Moeni Far, E. Najafi Birgani,
Volume 1, Issue 1 (1-2016)
Abstract
In this investigation, the effect of heat input of SMAW process on the corrosion behavior of Hadfield steel weld joints was investigated. For this purpose, 4 annealed sheets with thickness 25 mm prepared from Hadfield steel and then welding applied by SMAW process with 6.75 and 11.25 kJ/mm heat input values. For corrosion behavior evaluation of base metal and weld metal areas, potentiodynamic polarization and electrochemical impedance spectroscopy methods were used in the 3.5% NaCl solution. The result of corrosion tests indicated that by increasing the heat input in the SMAW process, the corrosion resistance in the weld metal were reduced. It was also found that in both heat input values, base metal had more corrosion resistance compared to weld metal.
Dr M. Safari, Dr H. Mostaan,
Volume 1, Issue 1 (1-2016)
Abstract
Weldability of high carbon steels due to the high percentage of carbon and consequently formation of martensitic structure is very poor. In this research, resistance spot welding of eutectoid high carbon steel 1075 is experimentally and numerically investigated from various points of view. The effect of welding current as one of the most effective parameters on failure mode, mechanical properties and nugget size diameter in resistance spot welding is analyzed with experimental tests and numerical simulations. The results show that with increase of welding current, the diameter of nugget size is increased and consequently the failure mode changes from interfacial mode to pull out mode.
M. Ahl Sarmadi, M. Shamanian, H. Edris, A. Behjat, M.a. Mohtadi Bonab, J. Szpunar,
Volume 1, Issue 1 (1-2016)
Abstract
In this study the microstructure and mechanical properties of super duplex stainless steel UNS S32750 welding was studied. For this purpose, the method of gas tungsten arc and filler metal AWS ER2594 with a diameter of 4.2 mm was used. In order to investigate the microstructure light microscopy and electron microscopy equipped with backscatter electron diffraction were used. Mechanical properties were studied by hardness and tensile tests. Weld metal had Cast structure with austenite in the dendrite form located in ferrite matrix. It was also observed in the melting zone after welding, the ferrite volume fraction decreased to 50 percent 60% base metal ferrite) ,Due to the low cooling rates and high heat input method in the gas tungsten arc welding. Vickers micro-hardness test method was carried out on the samples showed that average about 285 Vickers hardness of base metal; however, hardness in the fusion region due to increased austenite fraction fell to 250 Vickers. But hardness in the heat-affected zone due to lower volume fraction of austenite and ferrite phase formation of chromium carbide intermetalic compounds increased to 340 Vickers. The results of the tensile test showed that the tensile strength decreased with increasing heat input, because of increase the size of grains due to the increased heat input.
S. Sakiyan, H. Sabet, M. Abbasi ,
Volume 2, Issue 1 (8-2016)
Abstract
This Paper presents the welding parameter's effect (forging pressure, welding time) on macrostructure and mechanical properties of friction welding valve steel HNV3 to Nimonic 80A super alloy. For this purpose, two rods with 20 mm diameters are prepared and with using different parameters (Increase forging pressure and welding time) by friction welding method are welded together. Tensile Test carried out on samples for investigating the effect of a parameter. It was discovered that when the welding parameters used in connecting HNV3 and Nimonic 80A Superalloy couple through friction welding were selected correctly; strength of the connection would increase compared to the main material.
M. Ansaripour, A. Soltanpoor, A. Ghasemi, M.r. Dehnavi,
Volume 2, Issue 1 (8-2016)
Abstract
The aim of this study was to evaluate the mechanical properties and corrosion behavior of friction stir welding (FSW) connection of A517 (B) steel plate. Mechanical properties and corrosion behavior of weld zone were evaluated after reaching to optimum FSW microstructure with the lowest martensite phase. Thus, after the identifying phase microstructure by SEM and XRD analysis, mechanical properties were analyzed by micro-hardness and tensile test. Micro hardness data shows slight increases in stir zone (SZ) compared with the base metal (BM); although a reduction of about 17% in hardness of heat-affected zone (HAZ) was sensible. Reduction of hardness in the HAZ was appeared as drop by about 12 percent of the yield strength and 19 percent of ultimate strength compared with BM. SEM images from fracture surface of the tensile sample showed bi-modal distribution of large and small Dimples being sings of softness of HAZ .Comparing corrosion behavior in solution consist of 3.5 wt% of NaCl showed that there was no passive layers to prevent dissolution of the metal in the SZ and BM. while BM and SZ had fairly similar corrosion rates, Difference of 50 mV between corrosion potential of SZ and BM showed that in galvanic condition, corrosion resistance of BM could be lower than SZ.
M. Safari, H. Mostaan, A. Bakhtiari,
Volume 2, Issue 1 (8-2016)
Abstract
In this research, lap joint frictionstir welding of IF sheets with thickness of 0.7 mm is investigated. For this purpose, mechanical properties of joints and also microstructural evolutions are studied. It was found that increase in tool rotational speed and decrease in travel speed results in increase in fracture stress of welded joints. Texture study indicates that no changes can be observed in texture components after friction stir welding. This phenomenon in texture components can be related to high stacking fault energy of IF steel and consequently severe dynamic recrystallization during welding. The results show with increase in the tool rotational speed between 900-1400 Rev/min, ultimate force of fracture of friction stir welded joints is increased. Also, it is concluded from results that with increase in tool travel speed between 50-160 mm/min, ultimate force of fracture of welded joints is decreased. Finally it is proved from results of this paper that in the frictionstir welding of IF sheets with thickness of 0.7 mm, maximum force of fracture of welded joints is achieved in rotational speed of 1400 Rev/min and travel speed of 105 mm/min.
R. Ghasemi, E. Heshmat Dehkordi, M. Shamanian,
Volume 2, Issue 1 (8-2016)
Abstract
In this study, microstructural features and mechanical properties of Incoloy 825-316L stainless steel dissimilar joints have been investigated. For this purpose, pulsed gas tungsten arc welding method was employed and 316L, Inconel 82 and Inconel 625 alloys were used as filler metal. First, specimens were cut. Pulsed gas tungsten arc welding was performed using peak and base currents of 220 A and 110 A, respectively. Microstructure of welded joints was studied using metallographic observations and energy dispersive spectroscopy (EDS) analysis. In order to evaluate the mechanical properties, tensile and microhardness measurements were done on the joints. In all specimens, dendritic and equiaxed and/or cellular growth of austenite phase was observed. Incoloy 625 weld metal had the finest dendritic structure. Tensile test results revealed the ductile fracture with a high percent of elongation for all specimens. The highest tensile strength and percent of elongation of 610 MPa and 48% were obtained for specimen welded using Inconel 625 filler metal. Inconel 625 and 316 stainless steel weld metals showed the highest and lowest microhardness with values of 232 HV and 224 HV, respectively.
A. Behjat, M. Shamanian, M. Atapour, M. Ahl Sarmadi ,
Volume 2, Issue 1 (8-2016)
Abstract
High-strength low alloy steels are a class of steels used in applications that require high strength and good weldability, including ship hulls, gas pipelines and oil industry. One way to build parts is fusion welding that create areas with a large grain size in the heat-affected zone and increased susceptibility to hydrogen cracking. One way to solve this problem is to use solid state friction stir welding process. In this study, microstructural evaluation and mechanical properties of friction stir welding X-60 cross sections examined by optical microscope and by tensile and micro-hardness tests. The results indicate that changing welding parameters and thereby, change the heat input during friction stir welding have a great impact on maximum temperature and cooling rate that cause creating ferrite and bainitic ferrite in the weld zone. This change in microstructure of weld zone cause to improve mechanical properties that increase yield strength from 380 MPa to 420 MPa .Also, the friction stir process cause increasing hardness of 220 Vickers to an average of 280 Vickers and uniform distribution of hardness in the cross-section of friction stir joints.
Y. Najafi , F. Malekghaini, Y. Palizdar, S. Gholami,
Volume 2, Issue 1 (8-2016)
Abstract
Recent research suggests that extraordinary combinations of strength and ductility can be achieved in the so-called TRIP steels. With the development of these steels, welding with small weld nugget size and acceptable strength are needed. For these reasons present study was carried out to investigate the effect of heat input onweld size, microstructure and the hardness of the welded metal of 0.4%C- 4%Al δ-TRIP steel after continues fiber-laser welding process. To achieve this goal a bead on plate welding with three different values of heat input 28, 60 and 80 J/mm were used.The results of welding process revealed that by increasing the heat input, cooling rate decreased and the volume percent of the δ-ferrite in weld metal increased due to the availability of sufficient time for partitioning of Al in high heat input which leads to the stable δ-ferrite and as a result the difference between the hardness of the weld metal in comparison to the base metal decreased.
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. Ghasemi Tabasi, A. H. Kokabi,
Volume 2, Issue 2 (11-2016)
Abstract
The aim of this study is to reach an increased service life for parts using in sour environment by weld overlaying process. In this investigation, two successive layers of ER410NiMo were clad on low alloy steel substrates. To reduce the likelihood of Hydrogen Induced Cracking (HIC) and producing stable hydrogen traps, Post Weld Heat Treatment (PWHT) was conducted. Microstructural analysis, X-ray diffraction studies, and mechanical tests show significant increase for austenite volume fraction after second stage of PWHT. In fact, not only two-stage PWHT reduce the samples hardness, but it also increases austenite volume fraction which is a more resistant microstructure against hydrogen cracking.
M. Amelzadeh, S. E. Mirsalehi,
Volume 2, Issue 2 (11-2016)
Abstract
Nowadays, cemented carbides-steels joints by brazing method are taken into consideration. One of the problems of these joints is the creation residual stresses that can reduce it with choose correct parameters of brazing. In this study, Silver base alloy filler containing copper, zinc and cadmium have been used in temperature 780°C and the effect of time parameter 5, 10 and 15 minutes on microstructure and mechanical properties were investigated. The results indicated that brazing in 15 minutes causes a columnar growth of solid solution phase of copper from cemented carbide side to steel and provides maximum strength of 94MPa. As well as, by passing of time wetting angle of cemented carbide surface reduces from 40° to about 27°.
Mohammad Jula, Reza Dehmolaei, Seyed Reza Alavi Zaree,
Volume 2, Issue 2 (11-2016)
Abstract
In this paper, maximum value of energy to break at Charpy impact test as a criterion of fracture toughness of AISI 316/A387 Gr.91 weld joints with ERNiCrMo-3 filler metal were obtained by optimization of pulesd current gas tungsten arc welding process parameters. The selected parameters were peak current, background current, frequency and on time percentage that were changed in three levels. Therefore a L9 orthogonal array of Taguchi design including nine experiments for four parameters with three levels (34) was used. Analysis of signal to noise (S/N) ratio indicated that optimized values of peak current, background current, frequency and on time percentage were 120A, 90A, 10Hz and 80%, respectively. The welded specimen with optimized parameters showed an energy to break at Charpy impact test value of 65J at -20°c. The obtained results also demonstrated that the most influence on energy to break values belonged to background current, frequency, peak current and on time percentage, respectively.
Mahdi Lashkari Ghoochani, Behrooz Beidokhti,
Volume 2, Issue 2 (11-2016)
Abstract
In this research 420 martensitic stainless steel welded with the ER308L, ER309L and ER420 fillers by GTAW method. The corrosion properties of the samples has been studied in 3.5% NaCl solution with and without CO2. Potentiodynamic polarization used to obtain the ER308L and ER309L have the best corrosion properties. In addition the welding process makes the 420 HAZ zone to be sensitized. The pitting potential of the samples has been decreased in presence of carbon dioxide. Furthermore, by adding CO2 to the solution the pH has been decreased and the corrosion potential reached near the -500 mV/SCE and the passivity current is also lowered.
M. Safari, H. Mostaan,
Volume 2, Issue 2 (11-2016)
Abstract
In this paper, resistance spot welding process of AISI 201 stainless steel is studied experimentally. For this purpose, effect of welding current on quality of weld is investigated and relationships between welding current and fusion zone characteristics are examined. For determining mechanical properties such as maximum load and fracture mode, tensile - shear test of spot welds is performed. Hardness and microstructural examinations are performed for study the influence of welding current on characteristics of welded joints. The results show that strength of resistance spot welds of AISI 201 stainless steel is increased with increase in welding current. Transition of fracture mode from interfacial to pullout and then pullout with tearing of sheet mode during tensile-shear tests of AISI 201 spot welds is investigated through experimental and theoretical approaches. It is concluded from results that increasing in welding current leads to change in fracture mode from interfacial to pullout mode due to increase in fusion zone size (weld nugget size). Also, it is observed that increasing in fusion zone size is accompanied by an increase in load carrying capacity of resistance spot welds. The minimum required fusion zone size to ensure pullout fracture mode is estimated using an analytical model.
B. Sadeghi, H. Sharifi, M. Rafiei,
Volume 3, Issue 1 (8-2017)
Abstract
In this research, the microstructure and mechanical behavior of dissimilar joint of AISI 321 stainless steel to ASTM A57CL1 were studied. For this purpose, the GTAW process and ER 308L filler metal with diameter of 1.8 mm were used. In order to study the microstructure and fracture surface of weld samples, optical microscope and scanning electron microscope (SEM) were used. Also, the mechanical behavior of the joint was examined by impact, tension and microhardness tests. It was found that the microstructure of weld metal was austenite with skeletal ferrite. Also in some areas the lacy ferrite was seen. All samples were fractured from ASTM A537CL1 steel with a ductile manner during the tension test. The weld metal indicated high impact energy about 205 J.
M. Ahl Sarmadi, M. Shamanian, M. Atapour, H. Edris, A. Behjat,
Volume 3, Issue 1 (8-2017)
Abstract
In this study, the corrosion behavior of super duplex stainless steel UNS S32750 and tungsten arc welding with filler metals AWS ER2594 duplex stainless steel in acidic solution containing chloride ions have been investigated. Microstructure of weld joints evaluateby light and electron microscope and corrosion behavior examine by open circuit potential and cyclic polarization tests.The results showed that increas in heat input leads to a change in the distribution of alloying elements, formation of intermetallic phases around grain boundaries and the shifting balance between austenite and ferritein phases in weld region. Based on the cyclic polarization tests, cross-weld and base metal active behavior and have good corrosion resistance due to the presence of high alloying elements. As well as increase in heat input leads to an increase in current density and decrease in the pitting potential.
M. E. Kazemian, F. Mohsenifar, R. Ghanbarzadeh,
Volume 3, Issue 1 (8-2017)
Abstract
In this paper, laser beam welding of a rectangular piece of steel was simulated using Fluent software. Physical properties of analytical field was constant and its changes with temperature was ignored. In the present work, effect of tool speed and laser power on temperature distribution of workpiece surface and different deeps in the plane of symmetry and also maximum of temperature and depth of penetration were investigated. Using a macro code, geometry generation and meshing of the analytical field by helping required geometric parameters were provided for software. Moreover, laser radiation power was exerted by writing an UDF in the fluent software. In this case, it was assumed that the workpiece is stationary and gaussian thermal source model defined in UDF moves with the intended speed. Results show that at a constant power, maximum temperature of the workpiece decreases with increasing heat source speed, moreover, in this case, gradient of temperature in front of the workpiece and behind of it, increases and decreases respectively. It is found that the temperature in the depth of the workpiece increases with increasing the power.
A. Ghaedrahmati, M. Mosallaee Pouryazdi,
Volume 3, Issue 1 (8-2017)
Abstract
A517 is a low alloy high-strength steels that due to its high strength, toughness and weldability is used in ship building and submarine hulks. The welded areas of this steel often require repairs. In this study, the effect of number of welding repair on microstructure and mechanical properties of A517 steel is studied. Four samples (samples without repair, once repaired, twice repaired, and three times repaired) were welded by SMAW welding. Microstructural studies were carried out by using optical and scanning electron (SEM) microscopes. The effect of the number of repairs on mechanical properties of samples were investigated by using tensile, bending, impact and hardness The profile of hardness illustrated that the hardness in the heat affected zone near the base metal increased by repeated repairs while the hardness of this zone reduced in the third repaired sample. By repeating the welding repair, tensile and yield strengths of the welding areas were reduced and fracture impact toughness of heat affected zone at -51○C was increased. Generally, the results of tensile tests of second and third repaired indicated that the strength of these samples were not meet the ASME IX standard requirements, so welding steel A517 in the second and third repairs is not acceptable.
R. Abdolvand, M. Atapour, M. Shamanian, A. Allafchian,
Volume 3, Issue 2 (1-2018)
Abstract
Transient liquid phase bonding of UNS S32750 super duplex stainless steel to AISI 304 austenitic stainless steel using BNi-2 interlayer was carried out at 1050 oC for 45 min. Microstructure analyses of the joint were carried out using optical microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Microhardness indentation and shear strength test were performed to assess mechanical behavior of the joint. No eutectic contents was seen at the joint and thus Isothermal solidification was completed at 45 min bonding time. The shear strength of the joint was about 0.7 of duplex stainless steel shear strength. Froctographic studies revealed that the fracture mode was completely ductile in the case of the joint made at bonding time of 45 min.
