Inert Gas Welding Method Research Articles

Study on Fatigue Performance of Pulsed Tungsten Inert Gas Welding Joint of Duplex Stainless Steel Thin Tube.

To solve the shortage of austenite phase precipitation caused by nitrogen loss in the welding process of UNS S2205 duplex stainless steel (DSS), shielding gas nitriding was investigated by adding different N2 contents in Ar shielding gas during the welding process. A good thin-walled pipe butt joint was formed using the pulsed tungsten inert gas (P-TIG) welding method with Ar-N2 shielding gas. High cycle fatigue tests of the weld joints were conducted to study the effect of shielding gas nitriding on the fatigue properties. Fatigue tests at three stress levels of 225 MPa, 270 MPa, and 360 MPa were carried out on the weld joints with different N2 contents, and the fatigue samples were all fractured in the high temperature heat-affected zone (H-HAZ). Within the current process parameters, the fatigue life of the 4 vol.% N2 welded joints was optimal. Fatigue striations appeared in the fatigue crack propagation zone, and the transient fracture zone was similar to the tensile fracture. Under the low-stress level, the area of the crack propagation zone under 4 vol.% N2 was the highest, the tear ridges all expanded around the crack source area, and the fatigue crack propagation zone presented a radial distribution. The proliferation and expansion of dislocations were mainly carried out in the austenite grains, and the dislocation density of the fatigue specimens under 4 vol.% N2 was smaller than that of the Ar specimens. Shielding gas nitriding effectively improved the balance of the two-phase ratio and the hardness of austenite phase, optimized the internal slip system, inhibited the proliferation of dislocations in the austenite phase, and improved the fatigue life of weld joints.

Fabrication and characterization of incorporated nickel coatings with different loadings of tungsten carbide microparticles: Investigation of mechanical and chemical properties

This study aims to investigate the strengthening effect of incorporated nickel coatings with different weight percentages (wt.%) of tungsten carbide (WC) microparticles on the various properties of the applied coatings on plain carbon steel. Therefore, different applied coatings, including pure and reinforced nickel with various wt.% of tungsten carbide were applied to the samples using the tungsten inert gas (TIG) welding method. Then, the microstructure, wear behavior, hardness, and corrosion of the coated samples with pure and incorporated nickel with 5, 10, and 20% tungsten carbide were obtained and compared with the uncoated sample. The obtained results show that reinforcing the applied coatings with WC has improved the behavior of the coatings in different properties so that the filled coating with 20% of tungsten carbide had the best results. For example, the wear rate of coated surfaces reinforced with 5, 10 and 20% of tungsten carbide was 12.56, 7.52, and 5.28 mg/m, respectively, which was much lower than the uncoated sample with a value of 24.41 mg/m. The maximum coating hardness equal to 49.6 Rockwell C was obtained for nickel coating reinforced with 20% of tungsten carbide, which can be due to the high percentage of powder compared to other samples, and the formation of finer grains. The corrosion results of the samples using cyclic polarization diagrams showed the improvement of the corrosion behavior by adding tungsten carbide so that the nickel coating reinforced with 20% of tungsten carbide had a corrosion current density of 7.15 × 10−7 amps/cm2. Finally, the obtained results show that strengthening the applied coatings by the TIG method using different wt.% of tungsten carbide up to 20% can improve the various properties of the coating.

TIG-weldability of AISI 430 and DUROSTAT 500 grade

Abstract In this study, 10 mm thick DUROSTAT 500 and AISI 430 grades were joined by double sided keyhole tungsten inert gas (K-TIG) welding method without using filler material. The characterization of the microstructure of the weld zone was investigated by optical analysis methods and the mechanical properties of the welded parts were examined by mechanical tests. The fracture surface structure of the parts that were broken as a result of the tests were examined. No deterioration was observed in the welded samples. It was determined that the weld penetration increased as a result of the increase in the amount of heat entering the weld zone with the increasing welding current.

Parametric Prediction and Optimization of Mild Steel Geometry Composition Using TIG Welding Methods

The research focused on the application of the tungsten inert gas (TIG) welding method on mild steel metal materials and its optimization of the welding input factors along with its mechanical response parameters using the response surface method (RSM). The study has reviewed many research works alongside works of literature related to the study, and also revealed that the specific studied mild steel weld bead geometry mechanical properties on its weldment have not been studied to the best of the researchers' knowledge. The material under study is IS 2062, why the method applied for the analysis is the response surface method of optimization. The result shows the optimal solutions of both the input factors and the response parameters. The optimization results show that the optimal solutions for input process factors are: a gas flow rate of 16.00m3/s, welding speed is 113.221m/s, welding voltage is 18.00V, and welding current is 217.914A. The optimization results for the response parameters are; 344.628MPa for Hardness strength, 331.042 MPa for Yield strength, 25.272% for percentage Elongation, 452.780 for ultimate tensile strength, and 409.484 MPa for shear stress, and 118.00 J for impact energy response. The overall desirability of the models developed to achieve the optimal solutions result is 78.41%. The results will serve as bases for mild steel companies and industrialization. The research will also serve as a decision-making system in engineering and industrialization.

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.

Electrochemical Corrosion Behavior of MIG-Welded 7N01-T4 Aluminum Alloy by ER5356 and ER5087 Welding Wires.

7N01-T4 aluminum alloy plates were welded by the metal inert gas (MIG) welding method, with ER5087 and ER5356 welding wires, respectively. The electrochemical corrosion behavior of the weld zones in the two kinds of welded joints using 3.5 wt.% and 5 wt.% NaCl solutions were investigated by polarization curve, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and laser confocal scanning microscope (LCSM). The results indicated the better corrosion resistance of the weld zone in the ER5356 welded joint than that in the ER5087 welded joint, which was related to the different contents of Mn and Zn elements and the distribution of precipitates for the weld zones in the two kinds of welded joints. Based on the LSCM of the weld zones, the maximum depth (dmax) of corrosion pits for the weld zone in the ER5356 welded joint was lower than that in the ER5087 welded joint when immersed in the same NaCl concentrations. The dmax of the corrosion pit of the weld zone in the ER5356 welded joint using the 5 wt.% NaCl solution was 78.5 ± 0.96 μm, which was much bigger than that using the 3.5 wt.% NaCl solution. For the weld zone in the ER5087 welded joint with 5 wt.% NaCl solution, more Cl- was adsorbed onto the active surface of weld zones, which accelerated the corrosion, resulting in the corrosion mechanism from pitting to intergranular corrosion.

Effect of MIG Welding Parameters on the Mechanical Properties of AISI 304 Austenitic Stainless Steels

The present research investigates joints welding of 304L austenitic stainless steel using metal inert gas (MIG) welding method. The research explores the effect of process parameters (arc voltage, wire feed rate, and electrode wire diameter) on the mechanical properties of stainless steel. The above variables are varied respectively with 18.5, 19, 19.5 V, 116, 127, 137 mm/s, and 0.8, 1, 1.2 mm, with E308L as a filler electrode. The design matrix of the experiments was determined using the design of experiment (DOE) program Minitab 17 based on the levels of input elements used. The Taguchi orthogonal matrix methodology (Taguchi) technique was used to develop some empirical analysis for the maximum tensile strength and proper surface hardness as a function of the welding parameters mentioned above. The ( ) analysis was used to statistically verify the model's adequacy. The results show that the wire feed rate had the greatest effect on the tensile strength of the welded joints when choosing the medium level of arc voltage (19 V), while the arc voltage had a substantial influence on the micro-hardness of all welded joints. The weld-joint zone is given a higher micro-hardness value compared to the base metal zone.

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.

Effect of vanadium content on the microstructure and wear behavior of Fe(13-)VxB7 (x = 0–5) based hard surface alloy layers

In this study, Fe (13- x ) V x B 7 (x = 0, 1, 2, 3 and 5) based hard surface alloy layers were formed on SAE 1020 steel substrate surface by tungsten inert gas (TIG) welding method. The effects of vanadium addition on microstructure, hardness and wear rate in this coating layer were investigated using optical microscope, SEM (EDS), X-ray diffractometer, hardness and wear tests. As a result of microstructure studies and phase analysis, it was determined that the structures of alloy layers consist of α-(Fe,V), α-(Fe,V) + (Fe,V) 2 B eutectic, and (V,Fe)B phases. As a result of the macrohardness tests, it was found that the hardness of the alloy layers varied between 42.3 ± 1.7–57.2 ± 5.1 HRC. Moreover, the microhardness of iron and vanadium borides formed in the coating layers was found to be between 1901 ± 127–3082 ± 299 HV 0.01 , respectively. As a result of the wear tests, it was observed that as the amount of vanadium added to the hard surface alloy layer increased, the wear rates decreased for all applied loads. Morover, Scanning Electron Microscopy (SEM) images of the worn surfaces showed that the wear mechanisms were adhesive, micro-abrasive and oxidative. • Coating on Fe (13- x ) V x B 7 (x = 0, 1, 2, 3 and 5) based hardfacing steel surface with different vanadium content. • The effect of vanadium content on the microstructure of Fe-V-B based coatings. • Determination of the mechanical properties of the hard surface alloy layer depending on the vanadium content.

Statistical analysis of initial deflection of aluminium plating between stiffeners

Initial deflections caused by welding have a considerable effect on the ultimate strength of welded plate structures. Therefore, it is important to know the magnitude and shape of initial deflections. Much research has been conducted on the initial welding distortions of steel structures. However, for aluminium alloys’ structures, the data on fabrication-related initial deflections are minimal. Therefore, in this paper, the initial deflections caused by welding are investigated in aluminium plates used for marine structures. Initial deflections of plating between stiffeners are measured for different panels of four aluminium vessels. Vessels were constructed by the metal inert gas (MIG) welding method. Statistical analysis of measured data is carried out for estimating the maximum value of the initial deflections of aluminium plating between stiffeners. The results of this paper can be applied for the ultimate strength calculations of aluminium marine structures.

Effect of shielding gas combination on microstructure and mechanical properties of MIG welded stainless steel 316

AbstractThe quality of welded joints depends on the most optimal welding parameters and the selection of shielding gas type. The shielding gas was selected for joining stainless steels through gas metal arc welding methods by considering properties such as chemical-metallurgical interaction of shielding gas and the molten weld metal during the welding process, heat transmission capability of the gas and cost. In this study, the effect of different shielding gas combinations on the mechanical and microstructural properties of 316 austenitic stainless steel joined by the metal inert gas (MIG) welding method was investigated. In the welding process, pure argon (100 % Ar), 98.5 % Ar + 1.5 % H2and 95 % Ar + 5 % H2were used as shielding gases. Tensile, hardness, and bending tests were conducted to determine mechanical properties of the welded samples. In addition, metallographic examinations were carried out to detect the macrostructural and microstructural properties of weld zones. According to the results obtained from the study, the highest tensile strength was obtained from the joints welded using 100 % Ar shielding gas. When the addition of H2into the Ar gas increased, the tensile strength of the welded samples decreased. As a result of the tensile test, fractures occurred in the base metal in all welded samples. In all welding parameters, the hardness of the weld metal was lower as compared to the heat affected zone (HAZ) and the base metal. As a result of the bending test, crack and tearing defects were found in the weld zone.

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.

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.

Stress Corrosion Cracking Behavior of Tungsten Inert Gas Welded Age-Hardenable AA6061 Alloy

The effects of two temper conditions (T4 and T6 heat treatments) upon the stress corrosion cracking (SCC) of AA6061 plates have been investigated in this work. AA6061 alloys were double-side-welded by the tungsten inert gas (TIG) welding method. SCC behavior of both the as-welded and as-received alloys was reported. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to determine the precipitate structure of the thermal-altered zones and the base metal (BM), and also the hardness variations were examined using microhardness testing (Vickers hardness). The small-size precipitate structures in the T6 tempered alloy and the coarser precipitate structures in the T4 tempered alloy were found by microstructural investigations. As a result, T4 temper heat treatment of this alloy considerably reduced its susceptibility to stress corrosion cracks due to relatively coarse and more separate precipitate morphology. In welded specimens, SCC failure occurred in the area between the heat-affected zone (HAZ) and the base metal. Stress corrosion resistance in the fusion zone was strong in both temper conditions. The aim of this work was to obtain the effects of heat treatment and welding on SCC behavior of the age-hardenable aluminum alloy. The authors conclude that a deep insight into the SCC resistance of AA6061 alloy indicates the precipitate particle distributions and they are the key point for AA6061 alloy joints in chloride solution.

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.

Design Optimization of HANARO Irradiation Capsule for Long-Term Irradiation Testing

As HANARO has been recently required to support new R&D relevant to future nuclear systems requiring much higher neutron fluence, two types of bottom rod tip of the capsule were preliminarily prepared. The first one is a conventional design made of STS304 and welded using a tungsten inert gas (TIG) welding method. The other is a new design made of STS316L and welded using electron beam (EB) welding to strengthen the fatigue property of the rod tip. During the out-pile testing, they failed after 40 and 203 days, respectively. The fracture surfaces were examined using microscopes and the maximal applied stresses were estimated. The combination of these stresses was proved to be sufficient to cause a fatigue failure of the rod tip of the capsule. Based on the failure analysis, an optimized design of the rod tip of the capsule was made for long-term irradiation testing. It was designed to improve the welding and fatigue properties, to decrease the applied stress on the rod tip, and to fundamentally eliminate the effect of residual stress due to welding. The newly designed capsule was safely out-pile-tested up to 450 days and will be utilized for HANARO irradiation testing.

Effect of Repeated Repair Metal Inert Gas Welding on Microstructural Properties, Corrosion Resistance, and Wear Behavior of 5083-H116 Aluminum Alloy

The effect of repeated repair welding, shielded with argon, on microstructural properties, corrosion resistance, and dry sliding wear behavior of aluminum alloy 5083/H116 were investigated. Samples were welded by metal inert gas welding method. 100% argon was used to protect fusion zone. Aluminum alloy 5356 was used as the filler metal. The samples for microstructure, corrosion, and wear tests were prepared from welded and repaired plates. To study the microstructural properties, the samples were mounted, polished, and then etched by the Keller's solution. Optical microscopy was used for metallurgical analysis. The corrosion behavior was evaluated in 3.5% NaCl solution and at a temperature of 25 °C using a potentiodynamic polarization and electrochemical impedance spectroscopy methods. Dry sliding wear behavior was evaluated by pin on disc method and scanning electron microscopy.

Influence of vanadium filler on the properties of titanium and steel TIG welded joints

Fusion bonding of TiTi, FeFe and Ti/FeTi/Fe butt-welded joints through vanadium filler metal was investigated. Tungsten inert gas (TIG) welding method was employed. The microstructures of the welded joints were analyzed by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Mechanical properties of the joints were evaluated by microhardness tests and tensile tests. Vanadium exhibited good bonding with adjacent materials in Ti-Ti and Fe-Fe welded joints. Continuous solid solutions were observed in both Ti-Ti and Fe-Fe joints. Ti-V-Ti and Fe-V-Fe welds exhibited the average tensile strength of 416MPa and 434MPa, respectively. Vanadium, ER50-6 and ERTi-1 filler metals were applied to join Ti/Fe bimetallic sheet. Serious cracks were observed in the joint. XRD pattern of the fractured surface confirmed the Fe2Ti and σ intermetallics. The regions dominated by Fe-Ti compounds exhibited high hardness values (∼1112HV0.01). Cracks initiated and propagated in regions rich in Fe-Ti and σ intermetallic phases. The magnitude and distribution of welding residual stresses were estimated by finite element method. The peak Von Mises stresses (Ti-V-Ti, 501MPa; Fe-V-Fe, 555MPa) occurred in the base metals near V welds. The brittle intermetallics and high thermal induced stresses resulted in the cracking in Ti/Fe-Ti/Fe welded joint.

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.

Mechanical Properties, Corrosion Behavior, and Microstructures of a MIG-Welded 7020 Al Alloy

7020 aluminum alloy plates were welded by metal inert gas welding method, with the ER5183 welding wire containing Zr and ER5356 welding wire without Zr, respectively. The mechanical properties, corrosion behavior, and microstructures of these two welded joints were investigated. The tensile strength and ductilities of the joints are inferior to those of base alloy, and the lowest hardness is obtained in the welded zone, while the heat-affected zones are more sensitive to corrosion than the base metal and welded zones. The base metal shows a deformed subgrains microstructure, and the heat-affected zones still remain in elongated shape, where the soften zones form as a result of η′ (MgZn2) coarsening. Two welded zones are mainly characterized by as-cast structure; however, grains are refined and a zone of equiaxed grains forms along the bonding boundary due to the Zr addition into ER5183 Al alloy. Accordingly, the mechanical properties and corrosion resistance in this zone of the joint with ER5183 exhibit better than those of the joint with ER5356.