Tungsten Inert Gas Welding Method Research Articles

Effects of filler material selection on the microstructural, mechanical and corrosion properties of TIG welded AISI/SAE 304L stainless steel sheets and rings

Abstract Austenitic stainless steels are mainly preferred especially for resistance to aggressive oxidizing medias and high temperature applications such as equipments and mechanical parts which are used in defense and conventional industries. In this study; 3 mm thick 304L austenitic stainless steel sheets and rings are joined to each other by using Tungsten Inert Gas welding method under pure argon shielding gas with ER316L and ER2209 filler metals. Weld metals and heat-affected zones of welded joints were examined by metallurgical and scanning electron microscopes. Microhardness, tensile and Charpy impact tests of weld regions are investigated. It has been determined that the filler metals have dominantly changed the microstructure of weld metals. The microhardness values of the welded samples joined with ER2209 filler metal was lower than the sample joined with ER316L filler metal in weld metal regions. Besides, corrosion tests indicated that the corrosion rates of welded samples joined with ER2209 filler metal is lower than the samples joined with ER316L filler metal.

Investigating the Microstructural Properties and Phase Distributions of TIG Welded AISI/SAE 304L Stainless Steel Runners in TNT Filled Ammunutions

Among the stainless steels, the most widely used group is austenitic stainless steels. The prominent reason why austenitic stainless steels are preferred in welded stainless steel fabrications is their good weldability. AISI/SAE 304L austenitic stainless steels exhibit adequate corrosion resistance in oxidizing environments. AISI/SAE 304L austenitic stainless steels are also used in filling interfaces of runners between the Tri-Nitro-Toluen filling vessel and ammunitions in defense industry. For the manufacture of the runners, the stainless steel plates and the stainless steel pipes are mainly joined by fusion welding. These runners are cleaned with hot tapping water at 70°C after each filling of ammunitions by TNT so that cleaning operation can deteriorate the corrosion properties of runners especially weld zones. Austenitic stainless steel weldments include basically delta-ferrite and austenite phases on weld regions. Delta ferrite phase exhibits resistance to chloride bearing medias while austenite phase is more resistive to high temperature oxidizing ambients In this study; 3 mm thick 304L austenitic stainless steel plates and rings are welded to each other with two different filler weld wires of ER316L and ER2209 by Tungsten Inert Gas welding method under pure argon shielding gas. Weld metals and heat-affected zones of welded joints were examined using optical metallurgical microscope. It has been determined that the additional filler weld wires have changed the weld metal and the heat affected zone microstructures and phase distributions dominantly. Microstructures of all welded joints have been compared. Besides, phase distributions of weld metals and heat effected zones are made by image analysis software and Schaefflers diagram. ER2209 welding filler metal increased the phase fraction of delta-ferrite in weld metals while it decreased the austenite phase fraction as compared to ER316L filler metal.

Investigation of forming limit curves and mechanical properties of 316 stainless steel/St37 steel tailor-welded blanks produced by tungsten inert gas and friction stir welding method

The conventional welding method for joining dissimilar steels is the manual tungsten inert gas (TIG) method. Nevertheless, recently the benefits of solid state welding have been attracted attention of industrial manufacturers. In this article, TIG and friction stir welding method are compared based on the formability and mechanical properties of the welded sheets. Experimental evaluation of mechanical properties and forming limit curves have been carried out using uniaxial tensile test and Nakazima test, respectively. Results of experimental tests illustrated that formability of friction stir welded sheets was about 38% higher than the TIG-welded sheets. The microstructure analysis of TIG welded blanks revealed that grain growth in the heat-affected zone on the St37 steel, reduced the formability of welded joints in this method. Finite element simulation was used to estimate the forming limit diagram of the joints without considering the effects of welding heat on the material properties. The difference between the results of the FSW and finite element simulations was about 6%. While in the TIG welded blanks formability reduces significantly and difference between the result of experiment and simulation is about 33%. These results show that friction stir welding could more effectively preserve the sheets' formability after welding.

Tensile strength performance and optimization of Al 7068 using TIG welding process

The current scenario, to achieve better welding strength and quality of welded joints are challenging task. Tungsten Inert Gas (TIG) welding is one of the efficient welding methods to attain the quality of welded joints without any defects. The arc stability and intensity of the TIG welding was better than other welding processes. The aluminium 7068 was the superior strength alloy which it was processed under TIG welding method. The welding strength was estimated through different combinations of input factors such as current, voltage and weld speed. The parametric optimization was achieved through Taguchi method. The factors involvement and its effects have been studied through variance analysis and contour plot investigations.

New method to enhance the mechanical characteristics of Al-5052 alloy weldment produced by tungsten inert gas

Tungsten inert gas welding method is widely used to weld aluminum alloys. However, the development of some defects such as porosity and undercutting which form during tungsten inert gas welding may decrease the quality of the weld. Processing of the joint by friction stir processing is a method to enhance weld quality. In the current work, the weld area produced by tungsten inert gas is processed by friction stir processing as well as a novel processing method entitled “friction stir vibration processing.” In friction stir vibration processing, the specimen is vibrated while friction stir processing is carried out. The results show that both processing methods lead to grain refinement in the weld region and increase the strength and ductility of the tungsten inert gas–welded specimen. The stir zone grain sizes of friction stir vibration–processed samples are less than those of friction stir–processed ones. It is believed that workpiece vibration in friction stir vibration processing increases the material straining and intensifies the dynamic recrystallization. By application of friction stir processing on tungsten inert gas–welded specimen, ultimate tensile strength and ductility increase by about 10% and 22%, respectively. They increase by about 17% and 33%, respectively, as friction stir vibration processing is applied. The results also indicate that the effect of friction stir vibration processing on the microstructure of the weld region and its mechanical properties increases as vibration frequency increases. Friction stir vibration processing is a good alternative for friction stir processing, and it is recommended for application in industry.

PENGARUH FILLER PADA PENGELASAN TIG BAJA KARBON DAN STAINLESS STEEL 316L TERHADAP SIFAT MEKANIK

In the manufacturing industry, the integration of different types of material is needed. The dissimilar metal welding of two different material were required suitable filler types. The often combination of material was done is welding between steel and stainless steel. TIG (Tungsten Inert Gas) welding process used feed electrode an electric arc. The gas around welding area has been protected the molten metal with outside air. This study aimed to determine the effect of selecting a suitable filler on the joining dissimilar metal beetwen SS316L and low carbon steel with the TIG welding method. The mechanical characteristics of ER316L and ER70S filler variations were testing by Tensile strength and microhardness vickers. The highest tensile strength and hardness value were found in the specimen welded by ER70S filler at 410 MPa and 398,1 HVN (Hardness Vickers Number). According to the study results, the ER70S filler is more suitable beetwen welding on the stainless steel and low carbon steel.

Effect of welding parameters on microstructure and mechanical properties of AA7075/AA5182 alloys joined by TIG and MIG welding methods

In this study, V and X welding grooves were opened to the forehead positions of the AA5182 and AA7075 aluminum alloy pairs and these alloy pairs were joined with tungsten inert gas (TIG) and metal inert gas (MIG) methods. Three different welding currents were used in joints. Gas flow rates of 12 and 17 l/min at the TIG welding and wire feed rates of 38 and 45 cm/min at MIG welding were selected. The effect of the welding grooves, welding current, gas flow rate and wire feed rate on microstructure and mechanical properties were investigated. Microstructures of welding zones were analyzed by an optical microscope and a scanning electron microscope (SEM). Vickers hardness of these zones was also measured. In addition, tensile and fatigue tests were carried out. Fracture mechanisms of failed specimens were conducted after the tensile tests were examined by using SEM. The highest hardness, tensile and fatigue strengths were obtained from the alloy pairs joined by opening X welding groove with TIG welding method. These values were 89 HV, 262.87 MPa, and 131.5 MPa, respectively. Similarly, the lowest tensile and fatigue strengths were obtained from the alloy pairs joined by opening V welding groove in the TIG welding method. These values were, respectively, 94.48 MPa and 19.1 MPa. However, the minimum hardness value was measured as 58 HV from the alloy pairs joined by opening V welding groove with MIG welding methods. In addition, it was observed on the fracture surfaces that the grain distributions and mechanisms differed depending on the welding methods, welding groove, and welding parameters.

PENGARUH KUAT ARUS PADA PENGELASAN PADUAN ALUMINIUM 6061 DENGAN MENGGUNAKAN METODE LAS TIG TERHADAP KEKERASAN DAN STRUKTUR MIKRO

<em>The objective of research was to find out the effect of current on microstructure and hardness value in Aluminium Alloy 6061 before (raw material) and after welding using Tungsten Inert Gas (TIG) welding method with filler rod ER4043. This research uses experiment methods. Technique of analyzing data used was a descriptive comparative research. The instruments used for testing microstructure and hardness were Olympus Metallurgical Microscope and Vikers Hardness Tester. Base on the result of research, it could be concluded that the result of microstructure testing showed the reduced Mg<sub>2</sub>Si phase width after welding. In raw material, the Mg<sub>2</sub>Si phase seemed to diffuse surrounding the α-Al phase surface, but the result of welding using TIG welding method with current of I00 A, 110 A, and 115A showed that Mg<sub>2</sub>Si phase reduced in each specimen, so that α-Al phase was very dominant. The hardness value of hardness result showed the different hardness level. The specimen with current of 110A had higher hardness level of 65.4 VHN than the specimen with current of 100 A (55.7 VHN) and 115 A (55.9 VHN). The result of hardness testing on raw material was 120.4 VHN. This research showed that the welding using varying current changed microstructure and affected the hardness value of Aluminum Alloy 6061.</em>

Microstructure and mechanical properties of ultrasonic pulse frequency tungsten inert gas welded Ti-22Al-25Nb (at.%) alloy butt joint

Microstructural observations of cross sections of butt joints of Ti-22Al-25Nb (at.%) alloy manufactured using ultrasonic pulse frequency tungsten inert gas welding method at different welding parameters without and with welding wire, the butt joint at 50 KHz pulse frequency with welding wire has the largest equiaxed crystal zone, finest columnar crystals, and improves damage of dendritic crystals and overburning. The tensile strength, yield strength and elongation of butt joint at 50 KHz welding frequency with welding wire are the highest, compared with those of butt joints at other welding parameters without welding wire, and the fracture of it is ductile fracture mode of dimples. Further, fusion zone composed of α2 + β/B2 two phases and heat affected zone composed of α2 + O + β/B2 three phases in the butt joint having the highest tensile strength are determined using X-ray diffraction technology. In this butt joint, the microhardness of heat affected zone is the highest, followed by that of base material, fusion zone lowest.

Influence of Argon-Nitrogen Gas to Balance the Microstructure in the Welding of Super Duplex Stainless Steel

Super duplex stainless steel is steel that has a corrosion resistance and good mechanical strength so that used in industry especially in oil and gas and petrochemical industry. In use in the field is often used for the connection process by welding methods. To produce good welds, it should be noted that the welding procedures and parameters used , especially the heat input. In this study is used the heat input variables shielding gas composition to determine how much influence on the balance of ferrite - austenite phase structure in the weld stainless steels SAF 2507 super duplex with tungsten inert gas welding method (TIG). Heat input varied by applying different welding speed 1,3,4 and 5 mm /sec while the shielding gas is used 100 % argon, 98 % argon + 2 % nitrogen and 95 % argon + 5 % nitrogen. The result showed that at different welding speeds generated depth and width of the weld metal which is different. Likewise the use of protective gas will produce a different ratio wide and deep of weld metal which is different. By using protective gas 95 % argon + 5 % nitrogen squeak - ausenit phase, resulting in weld metal that is relatively balanced than others. On a slow welding in addition to produce a large heat input also produces weld metal hardness at high and affect the growth of the austenite phase. The higher the heat input ( 2,280 kJ / mm ) , the lower the austenite phase in the weld metal.

The microstructure evolution and element segregation of Inconel 617 alloy tungsten inert gas welded joint

Abstract

Effect of Continuous and Pulsed Currents on Microstructural Evolution of Stainless Steel Joined by TIG Welding

Abstract In this study, AISI 316L series austenitic stainless steel sheets were joined by tungsten inert gas welding method in continuous and pulsed currents. Regarding microstructural investigation and hardness values of weld metal, samples were welded to investigate the effect of current type on grain structures of weld metal. Results showed that samples welded by using pulsed current had considerable different properties compared to the samples welded by using continuous current. While the weld metals of joinings obtained by using continuous current displayed a coarse-grained and columnar structure, weld metals obtained by using pulsed current had a finer-grained structure. It was also found that hardness values of samples, which were welded with continuous and pulsed current, were quite different.

High-Temperature Corrosion Behavior in Different Regions of 9 Cr-1 Mo Steel Weldment in SO2 + O2 Atmosphere

This paper investigates the high-temperature corrosion behavior of microstructurally different regions of the weldment of 9 Cr-1 Mo steel used in thermal power plant boiler in SO2 + O2 environment. The weldment is produced by tungsten inert gas welding method, and the different regions of the weldment (weld metal, heat-affected zone, and base metal) are exposed in SO2 + O2 (ratio 2:1) environment at 973 K for 120 h. The reaction kinetics and corrosion growth rate of different regions of weldment in isothermal condition are evaluated. The post corroded scales of the different specimens are studied in SEM, EDS, and XRD. The results indicate that the weld metal shows higher corrosion rate followed by HAZ and base metal. The higher rate of corrosion of weldmetal is mainly attributed to the least protective inner scale of Cr2O3 with minimum Cr Content. This is due to the formation of delta ferrite, which leads to the precipitation of the Cr-based secondary phases and depletes the free Cr from the matrix. The thermal cycles during welding at high temperature are favorable for the formation of delta ferrite. On the other hand, in absence of delta ferrite, the base metal and HAZ regions of the weldment show lower corrosion rate than weld metal. The difference in corrosion rate in the three regions of the weldment is supplemented by post-corroded scale characterizations.

Microstructure and Wear Resistance of an Arc-Sprayed Fe-Based Coating After Surface Remelting Treatment

The aim of the study was to improve the lamellar structure and wear resistance of arc-sprayed coatings. FeNiCrAl arc-sprayed coatings were remelted by the tungsten inert gas welding method. The as-sprayed and remelted specimens were subjected to comparative structural phase composition examination using optical microscopy, scanning electron microscopy and X-ray diffraction. Additionally, the effect of the remelting treatment on the wear mechanism of the arc sprayed coatings was also studied. It was found from the experiments that the tungsten inert gas surface process has the potential to form pore- and crack-free coatings. Further investigations showed that the dominant mechanism of wear for the as-sprayed coatings was oxide delamination and for the tungsten inert gas remelted coatings was cutting and ploughing.

Development of high frequency tungsten inert gas welding method

A new welding method, called high frequency tungsten inert gas (TIG) welding, was developed to decrease blowholes in a weld. A1050 aluminum alloy plates (100mml×50mmw×5mmt) were welded at a frequency from 10 to 40kHz. An Ar-1% hydrogen mixture was used as the shielding gas to generate blowholes in the experiments. The welding was performed in the horizontal position so that the blowholes can easily be a problem. For comparison, a normal TIG welding was also performed at 60Hz. After welding, the distribution of the blowholes in the welds was observed in order to evaluate the effect of the sonic wave. The number of blowholes changed with the frequency. A frequency near 15kHz is the most suitable to decrease the blowholes. Using this new method, the area of blowholes is decreased to less than about 1/8 of the normal TIG weld. This method is much more effective for decreasing the number of blowholes, compared with an ultrasonic wave vibrator which is directly fixed to the sample.

Microstructure Characterization of AZ91D Magnesium Alloy Weldment Using Tungsten Inert Arc Welding Method

The problem during magnesium alloy welding is the key bottleneck of magnesium application in aerospace, aircraft, automotive and other industries. AZ91D magnesium welded joint is obtained using tungsten inert gas (TIG) welding method without filler materials and groove. The microstructure, morphology, composition and micro hardness distribution of welded joint are investigated using scanning electronic microscopy (SEM), EDAX and micro hardness experiment. The results show: (1) Well welded joint of AZ91D magnesium alloy using TIG welding method is obtained under the condition of welding current 152A, welding voltage 13.4V, welding velocity 6.5mm/s and 20L/min Argon shielding gas; (2) Microstructure of welded joint consisted of black matrix phase α-Mg, white eutectic α+Mg17Al12 and gray dendrite.

Experimental investigation and design of aluminum columns with longitudinal welds

This paper presents an experimental investigation of longitudinally welded aluminum alloy I-section columns subjected to pure axial compression. The specimens were fabricated using 6061-T6 heat-treated aluminum alloy. The test program included 20 column tests which were separated into 2 test series of different types of welding sections. Each test series contained 10 columns. All the specimens were welded using the Tungsten Inert Gas welding method. The length of the specimens ranged from 442 to 2433 mm in order to obtain a column curve for each test series. The observed failure mode for the column tests includes mainly flexural buckling around the minor axis and the major axis by applying support except for one column (ZP1217-1) which buckled in the local zone and some columns which failed in the weld. The test strengths were compared with the design strengths predicted by the European Code and China Code for aluminum structures. The purpose of this paper is to present the tests results of two typically longitudinally welded I-section columns, and to check the accuracy of the design rules in the current specifications.

HIGH EFFICIENCY WELDING PROCESS FOR STAINLESS STEEL MATERIALS

The high efficiency tungsten inert gas (TIG) welding process has been developed, including active flux welding process, mixed shielded welding process and double shielded welding pro- cess, to increase the weld depth/width ratio (D/W ) of conventional TIG welding method. Compared to the active flux method, mixed shielding method can make penetration deeper and the industrializa- tion can be realized easily due to the simplification in operation. Double shielded method can avoid the oxidation of tungsten electrode. The results of experiment and simulation show that the change of the Marangoni convection direction which arises from the adjustment of the oxygen content in the weld pool is one of the main factors contributing to the increase in TIG weld penetration, and the large D/W ratio can be obtained by adjusting the active element content in the liquid pool. High efficiency TIG welding process is not sensitive to welding parameters (welding speed, welding current and electrode gap) and therefore is suitable to be applied in industry easily.

Abrasive wear characteristics of coating area of low carbon steel surface alloyed through tungsten inert gas welding process

Low carbon steel surfaces were alloyed with composite powders using the tungsten inert gas welding method. After the alloying process, the effects of welding parameters, such as energy input, progress speed and coating thickness on the microstructural characteristics of the alloyed samples were examined. In the experimental investigation, a low carbon steel surface was alloyed with austenitic stainless steel powder and austenitic stainless steel composites mixed with 4·5% Co, Mo and Ti particles respectively. Following surface alloying, conventional characterisation techniques, such as optical microscopy, scanning electron microscopy, energy dispersive spectrograph and X-ray diffraction, were used to study the microstructure of the alloyed zone. Hardness measurements were also performed across the alloyed zone. Examination of the microstructure revealed the presence of M23C6 carbides, solid melt phases, and intermetallic phases, such as Ni3Ti, depending on the alloying element in the composite. As the amount of the reinforcing material increased, the saturation rates for the samples decreased, while their hardness increased. The abrasive wear tests conducted revealed that temperature input plays a significant role on the microstructure characteristics, which positively affected the abrasive wear values of the samples. Consequently, the tungsten inert gas welding method was successfully used for the surface alloying of low carbon steels.

Effects of different metals on adhesive wear behaviour of alloy surface produced by TIG process

Low carbon steel surfaces were alloyed with composite powders using the tungsten inert gas welding method. After the alloying process, the effects of cladding surface on the microstructural characteristics and adhesive wear of the alloyed samples were examined. The sliding wear behavior of samples was investigated in a block on ring apparatus under the loads of 20, 40, 60 and 80 N respectively. In the experimental investigation, a low carbon steel surface was alloyed with austenitic stainless steel powder and austenitic stainless steel powder mixed with 4·5% Co, Mo and Ti particles respectively. Following surface alloying, conventional characterisation techniques, such as optical microscopy, scanning electron microscopy, energy dispersive spectrograph and X-ray diffraction, were used to study the microstructure of the alloyed zone. Examination of the microstructure revealed the presence of M23C6 carbides, solid melt phases and intermetallic phases, such as Ni3Ti, depending on the alloying element in the composite. As the amount of the reinforcing material increased, the saturation rates for the samples decreased, while their hardness increased. The adhesive abrasion tests conducted revealed that temperature input plays a significant role on the microstructure characteristics, which positively affected the adhesive abrasion values of the samples. Consequently, the tungsten inert gas welding method was successfully used for the surface alloying of low carbon steels.