The effect of electromagnetic vibration on the microstructure and impact toughness of API-X70 steel weld metal was investigated. The welding was carried out by GTAW process and using filler metals including ER80S-G and ER309L. Electromagnetic vibration under voltages 0, 12, 20 and 30 volts concurrent with welding was applied. The microstructure of the base and weld metals using optical microscope and SEM was studied. The impact energy of weld metals at TR, 0°C and 20℃ using charpy impact test was measured. Microstructural investigations of ER80S-G weld metal showed that applying electromagnetic vibration and increasing the intensity of applied vibration cause the finer and more uniform of Martensitic-Austenitic (MA) islands. The results showed that, due to electromagnetic vibration, the microstructure became finer and the average size of dendrites in the ER309L weld metal decreased from 18.19 to 8.01 μm. Microscopic studies before etching showed that, the applying of vibration caused finer and more uniform distribution of precipitations. The impact test result, illustrated that with the increasing in applied vibration cause improvement of impact energy of weld metals at different temperature (TR, 0°C and -20℃). It was found that with vibration under 30V, impact energy of ER80S-G weld metal in TR, 0°C and -20℃ was increased equal to 53, 29 and 36 percents, respectively. Besides for ER309L weld metal, the impact energy in TR and -20℃ was increased equal to 18 and 5 percents, respectively. With the application of electromagnetic vibration in the ER80S-G weld metal, the hardness increased due to the finer structure and also the formation of acicular ferrite, which produced the highest hardness at 30V vibration. The electromagnetic vibration in the ER309L weld metal increased the hardness due to the break down and finer of dendrites. Corrosion rate was reduced by increasing the vibration rate up to 20 volts in the ER80S-G weld metal due to the grain finer and the uniform distribution of phases and the finerization of the precipitations and the formation of a uniform layer of compact and dense corrosion. However, the corrosion rate increased with increasing vibration of up to 30V and increasing grain refinement and grain density. The highest corrosion resistance was observed at the less heat input. With the application of electromagnetic vibration in the ER309L, due to the break down of the dendrites, the stability and compression of the protective film, the distribution of alloying elements and the rich protective layer of chromium, the corrosion properties were greatly improved. (TR= Temperature Room)

 Ferritic heat resistant steels to austenitic stainless steels joints is widely used in boilers, heat exchangers and nuclear power plants. In this study the effect of gas-tungsten arc welding process parameters with pulsed current on mechanical properties and corrosion resistance of heat-resistant steel A387-Gr.91 to Austenitic stainless steel AISI 316 joint by ERNiCrMo-3 filler metal is investigated. Accordingly, the maximum current, background current, frequency and on time percentage as the important parameters of the welding process are changed at three levels. Experiment design based on Taguchi method with orthogonal array L9 (34) was performed and the results are analyzed using signal to noise ratio. The analysis of the impact test results showed that the background current, frequency, maximum current and on time percentage had the highest effect on the absorbed energy in the impact test respectively, and the optimal values of 90 A, 10 Hz, 120 A and 80% are obtained for them respectively. The impact energy for optimal specimen with pulse current and the specimen with constant current is obtained as 65 and 54 J respectively which demonstrates the positive effect of pulse current on the fracture toughness compared to a constant current. In addition, the analysis of polarization test results indicated that the maximum current, frequency, on time percentage and background current had the highest effect on the rate of uniform corrosion and the optimal values of 135 A, 10 Hz, 80% and 75 A are obtained for them respectively. Uniform corrosion rates for the optimal specimen with pulse current and specimen with constant current are 0.00009 and 0.00066 mm per year that indicates improved uniform corrosion resistance in welding with the pulse current. Also on time percentage, maximum current, frequency and background current had the highest effect on pitting potential and the optimal value of 60%, 120 A, 6 Hz and 60 A are obtained for them respectively. Pitting potentials for the optimal specimen with pulse current and specimen with constant current are 1.09 and 0.92 V that demonstrates the use of pulse current has improved pitting corrosion resistance. Microstructural studies showed that pulse current makes weld metal structure finer and reduces the rejection of alloy elements to the interdendritic zone and the formation of secondary phases. In addition, microstructure studies showed that the width of the unmixed zone is significantly reduced by pulse current.

Dissimilar Weldment have been widely used in the oil and gas industry. With the development of oil and gas exploitation in deepwater, more and more dupplex stainless steels (DSS) have been used in the flowline; however, low alloy steels are used in the cool end flowline section for economic consideration. Therefore, dissimilar weld joints are unavoidable. This study was conducted to investigate the effect of Electromagnetic vibration on microstructure and properties of dissimilar joint between 2205 duplex stainless steel and high strength low alloy steel API5L X80. welding was done with ER2209 filler metal. In order to investigate the effect of Electromagnetic vibration, welding was done bu applying the magnetic field in 0, 6, 12, 20, 30 voltage. microstructural studies by optical and electron microscopy were performed in different areas of joint. Mechanical properties of the weld were investigated by hardness and impact tests. In order to investigate the corrosion behavior of the weldment have used cyclic polarization corrosion test. Fractured surfaces were examined using scanning electron microscopy. increasing the intensity of vibration, causing severe decreases of grain size, increases the amount of austenite and the impact energy of the weld metal. With increasing the intensity of vibration, causes decreases the wide of unmixed zone and improved the corrosion resistant of the weld metal.

 Fine-grainedness of structure of the weld metal has a significant effect on the binding properties. One way to improve the microstructure and reduce the grain size, is using electromagnetic vibrations during welding. In this study, samples of Incoloy825 super alloy were welded under electromagnetic vibration with different intensity of output voltages, 6,12,20,25 and 30V and using filler metal of inconel82 and GTAW technique. Microstructure of base metal and different areas of weld was studied by light and electron microscopy in different conditions of welding. mechanical properties of the weld were investigated by Vickers hardness and charpy impact tests. Corrosion behavior was investigated by cyclic polarization tests. The results show by increasing the voltage and electromagnetic vibrations, structure of weld metal changes to fine grain and precipitations are smaller and more dispersed, due to dendrites breaks. Also, mechanical test results show an increase in toughness of weld metal because of dendrites breaks between dendrites arms due to increasing vibrations. Meanwhile, the results present the high effect of electromagnetic vibrationon HAZ (HEAT AFFECTED ZONE) and grain growth near this area and homogenous distribution of alloy elements . also corrosion resistance of weld metal was improved because of homogenous distribution of precipitation in higher voltages.

Dissimilar weldments have been widely used in the oil and gas industry because of economic benefits as well as the full advantage of outstanding performance of two different metals, such as strength and corrosion resistance. With the development of oil and gas exploitation in deep water, duplex stainless steel(DSS) have been used in the flow line; however, low alloy steels are used in the end section of flow line for economic consideration. Therefor, dissimilar weldments are unavoidable. This study was conducted to investigate the effect of GTAW parameters on properties of dissimilar weldment between 2205 duplex stainless steel and high strength low alloy steel API-5LX80. In order to investigate the effect of heat input, welding was done in 0.68,0.84,1.12 Kj/mm using ER2209 filler metal. To investigate the effect of heat input on thermal cycles, 10 thermocouple are used near the fusion line. Microstractural studies by light and electron microscopy were performed in different areas of joint. Likewise; mechanical properties of the weld were investigated by hardness and impact tests. Fractured surfaces were examined by using scanning electron microscopy. Ferrite content of weld metal was measured by ferritescope. In order to investigate the corrosion behavior of the weldments, cyclic polarization test have been used. Results show that with increasing of heat input causing increase the amount of austenite and impact energy of the weld metal. Also increasing heat input, led to wider and higher thermal cycles with increasing heat affected zone. Ferrite-Austenite balance controlling is primarily parameter on the pitting corrosion behaviour of ER2209 filler metal.

Nickel-base superalloys are most complex compounds that used in high temperature components.incoloy 825 is an iron-nickel base super-alloy that strengthen by solid solution and the presence of the carbide and nitride in its austenitic matrix.In this study, welding of Incoloy 825 were made with three different filler materials including: 309 stainless steel and nickel-based Inconel 182, and 625. In order to investigate the heat input effect on the binding properties, samples were welded by Inconel 625 filler metal in three different heat inputs as0.48 (kj/mm),0.68 (kj/mm) and 0.82 (kj/mm). The microstructure of the base metals, weld metals and their interfaces were characterized by utilizing optical and scanning electron microscopy. Study indicatedNbC carbide precipitates form in theinterdendritic regions of incoloy 182 and is formed lave phase and NbC carbide in weld metal of incoloy 625, and formed δ ferrite in interdendritic regions of weld metal of 309 stainless steel.Tensile, hardness and impact tests were employd in order to study the mechanical properties. It was found that samples of Inconel 625 weld metal had better mechanical properties than the other two samples. Also among samples with different heat inputs, Inconel 625 of 0.48 (kj/mm) heat input showed higher impact resistance, strength and hardness compared to other samples.

Duplex stainless steel 2205 and high strength low alloy steel API 5L X80 are have been widely used in oil and gas transportation industries. Duplex stainless steels are used in onshore and inviroment, however high strength low alloy steels are used in offshore for economic consideration of oil and gas transportation. Therefore dissimilar weldjoints are unavoidable. This study was conducted to investigate the effect of Shielded Metal Arc welding parameters on dissimilar joint between duplex stainless steel 2205 and API 5L X80 properties. In order to investigate the effect of filler metal on joint properties, welding was done by E2209 and E309L electrodes. Although to investigate the effect of heat input, welding was done in 0.54, 0.7 and 0.81kJ/mm heat inputs by using E2209 electrod. To investigate the effect of heat input on thermal cycles, 10 thermocople are used near the fusion line. The samples were prepared to investigate the microstructure and mechanical properties. Mechanical behaviors of the joints were studied by hardness, microhardness and charpy impact tests. Microstructures of welded joints are investigated using scanning electron microscopy/energy-dispersive analysis (SEM/EDAX) technique and optical microscope (OM). Fractured surfaces were examined using scanning electron microscopy. Ferrite content of the weld metals were measured by the amount of feritescope. Results indicated that, E2209 electrode is the finer electord. Also increasing heat input, led to wider and higher thermal cycles with increasing heat affected zone. Heat input increase result in higher austenite content of weld metals produced by E2209 electrode. By increasing austenite content, hardness decreased and thoughness had improved.

Al-Si alloys are weidely used in automotive and aerospace applications because of their low thermal expansion coefficient, good wear resistance anddimensional stability. Aluminium alloy 1050 is a popular grade of aluminium for general sheet metal work where moderate strength is required. Its well known due to the excellent corrosion resistance, high ductility and highly reflective finish.The friction stir welding (FSW) processhas become a highly recognized joining technique due tonumerous advantages including easier joining ofthe hard-to-weld materials such as aluminum alloys anda lowerheat input compared to fusion welding.In this study, effect of the silicon content on the weldability, mechanical properties andmicrostructure aspects of different region of the weld in casting alloys aluminum silicon with various percentages of silicon, tested by friction stir welding (FSW) method. Mechanical tests and Varestraint test were performed on the samples with strain rate of 1-4 percent. Microstructure of the base metal and different region of the weld were examined by light and electron microscope equipped withEDS system. The results show that AA1050 alloy has the best weldability and the weakest is belonged A390.with increasing of the applied strain and percent silicon susceptibility to hot cracking is increased. Alloy A390 has themaximumhardness and minimumimpact resistance however alloy AA1050 has a minimum hardness and maximum impact resistance. By increasing the silicon amount the hardness of materials was increasing and the weldability and impact resistance was decreasing.

Abstract:310 AISI steel is one of the most common alloys used in high-temperature oxidizing environments due to its high levels of alloying elements such as chromium and nickel, and because of its austenitic structure.incoloy 825 is an iron-nickel base super-alloy that strengthen by solid solution and the presence of the carbide and nitride in its austenitic matrix. In this study,310 AISI stainless steel and incoly 825 super-alloy were joined to each other by GTAW method. Filler metals such as inconel 82, Inconel 625 and310 stainless steel were used for welding. In order to investigate the heat input effect on the binding properties, samples were welded by Inconel 82 filler metal in three different heat inputs as 2.52,2.88 and 3.24 (kj / mm). micro structural evaluation was performed on the weld metal, base metal and the heat affected zone after the welding. OM and SEM and EDS Analysis were used to investigated the microstructure of different zone. percipitate were detected in the base and weld metal of incoloy 825. Partial melted zone and unmixed zone , epitaxial growth, invisible boundaries were observed and studied. Results showed that increasing the heat input, increased the grain growth and precipitate dissolution .Tensile, hardness and impact tests were employd in order to study the mechanical properties. It was found that samples of Inconel 82 weld metal had better mechanical properties than the other two samples. Also among samples with different heat inputs, Inconel 82 of 2.55 (kj/mm) heat input showed higher impact resistance, strength and hardness compared to other samples.

In dissimilar welding metals, microstructure study of weld and areas around it and selecting the appropriate filler metal are very important. In this study, Dissimilar welding of 316L stainless steel and high strength low alloy steel API 5L X80 with two processes of gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) was performed. For this purpose, ER316L-16, ER309L-16 and ER2209 filler metals and E316L-16 and E309L-16 electrodes were used. Also, Effect of heat input on microstructure of weld metal and the heat affected zone has been studied for ER2209 filler metal. After welding operations in order to study the microstructure several samples with appropriate dimensions according to the related standards were prepared and the microstructure of base metals and weld metals and the HAZ were studied by optical microscope and field emission scanning electron microscope (FESEM) equipped with the analyzer the EDS. For investigate the mechanical properties of the weld metal, hardness and impact tests were performed. The results showed that, the ER2209 filler metal has better mechanical properties than other filler metals and electrodes. The results showed that, heat input can improve impact energy with increases the amount of weld metal austenite.

Dissimilar weldments have been widely used in the oil and gas industry because of economic benefits as well as the full advantage of outstanding performance of two different metals, such as strength and corrosion resistance. With the development of oil and gas exploitation in deepwater, more and more duplex stainless steels (DSS) have been used in the flowline; however, low alloy steels are used in the cool end flowline section for economic consideration. Therefore,dissimilar weld joints are unavoidable. This study was conducted to investigate the effect of Pulse Current Gas Tungsten Arc Welding (PCGTAW) parameter on microstructure and properties of dissimilar joint between 2205 duplex stainless steel and high strength low alloy steel API 5L X80. In order to investigate the effect of filler metal, welding was done with ER2209, ER309L and KJS 124 filler metal. In order to investigate the effect of heat input, welding was done in 1.55, 1.96, 2.53 KJ/mm with ER2209 filler metal. To study the effect of pulse frequency welding was performed in 5, 10 and 15 Hz frequencies. Microstructural studies by light and electron microscopy were performed in different areas of joint. Mechanical properties of the weld were investigated by hardness and impact tests. Fractured surfaces were examined using scanning electron microscopy. Weld metal ferrite content was measured by the amount of ferritescope. The results showed that joint with ER2209 filler metal has better mechanical properties than other joints. Also increasing the pulse frequency, causing severe decreases of grain size, increase the amount of austenite and the impact energy of the weld metal. With Increasing of heat input the weld metal austenite and impact energy is increased

 X80 and X70 micro- alloyed steels have found many applications in gas transmission pipelines due to their high strength, suitable low temperature toughness and good weldability. In the present study, microstructure and mechanical properties of X80 and X70 micro- alloyed steels dissimilar joint were investigated. For this purpose gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) processes employed. Different welding current applied to optimize the heat input.then the samples were prepared to investigate the microstructure and mechanical properties. The microstructures of welded joints are investigated using scanning electron microscopy/energy-dispersive analysis (SEM/EDAX) technique and optical microscope (OM). Phase constituents of joints studied by X-ray diffraction (XRD). Mechanical behaviors of joints analyzed with Tensile, hardness and impact tests. The results indicated that with increase in heat input in both processes, heat affected zone (HAZ) becomes more coarse and its width becomes wider. The hardness also decreases with increase in the heat input.