Increasing Welding Current Research Articles

Effects of resistance spot welding parameters on microstructure and mechanical properties of the dissimilar welded joint of quenching and partitioning steels

Abstract In this study, the effect of welding currents and welding times on the microstructure and mechanical properties of the dissimilar welded joints of Q&P980 and Q&P1180 steel was investigated. The macrostructure and microstructure of the dissimilar welded joints were characterized and the relationship between the welding parameters and the mechanical performance was analyzed using confocal laser scanning microscope, scanning electron microscope, and mechanical properties testers. Results show that with the increasing welding current and welding time, the nugget diameter, indentation rate, and maximum shear force of the dissimilar joint increase. The absorption energy of the dissimilar joint increases when the welding current rises, while it increases first and then decreases with elevating welding time. All the hardness distributions of the dissimilar Q&P980/Q&P1180 joints exhibit the highest hardness value in the fusion zone and a gradually decreasing hardness value in the heat-affected zone. Moreover, with increasing current and time, much higher hardness occurs at the FZ/HAZ boundary. The microstructure characterization illustrates the martensite fraction in the intercritical heat-affected zone of the Q&P1180 side is higher than that of the Q&P980 side after the welding process. With the increase of welding current and time, the lath martensite in the fusion zone gradually coarsens. The coarsening martensite and the nugget diameter are responsible for the change in the shear force and energy absorption of the dissimilar Q&P980/Q&P1180 joints.

Microstructure and mechanical properties of resistance spot welded dissimilar aluminum/steel joints fabricated using high entropy alloy as interlayer

To improve the welding quality of Al/steel joint during resistance spot welding (RSW) process, a CoCrFeNiMn high entropy alloy (HEA) sheet was employed to be an interlayer between aluminum alloy and high strength steel parent metal sheets. Through a series of comparative studies and analyses, the Al/steel spot welded joint obtained from the process with the HEA interlayer had a larger aluminum nugget diameter and thinner intermetallic compound (IMC) layer when compared to a conventional RSW process. When the thicknesses of two parent metal sheets were 1.0 mm or 1.5 mm, the aluminum nugget diameter of the Al/steel spot welded joint with the HEA interlayer were 4.904 mm and 5.962 mm, and respectively increases by 28.41% and 31.32% compared to a conventional RSW process. For the 1.5 mm of the thickness of the parent metal sheets, the HEA interlayer can make the layer thicknesses at the Al/steel faying interface decrease from 3.2 μm to 1.3 μm. Also, adding the HEA interlayer could induce more welding heat energy respectively by 30.74% and 30.34%, and significantly improve the lap-shear strength of the joint by 56.95% and 52.09% for two thicknesses of the parent metal sheets. Even increasing welding current of the process without HEA interlayer to make its calculated welding heat energy the same as that with HEA interlayer, the Al/steel joint obtained from the process with HEA interlayer still had a higher lap-shear strength. In addition, by seriously observing and analyzing the fracture surfaces obtained from processes with and without the HEA interlayer, it could be concluded that the HEA interlayer could improve the fracture mode of the Al/steel joint from interfacial fracture to button fracture, so the quality of the Al/steel joint could be improved. This work can supply an effective method to improve the dissimilar metals welding process.

PENGARUH VARIASI KUAT ARUS SMAW TERHADAP SIFAT MEKANIK BAJA AISI 1045

This study discusses the effect of variations in the parameters of the welding process on the tensile strength and Vickers hardness tests. In general, it is widely known that in the fabrication process, welding is a very important process that is used to join two or more materials. The welding process is carried out with variations in the strength of the welding current, namely 75, 85, and 95 A. The experimental method used in this research is AISI 1045 steel material with a thickness of 6.0 mm. The results of the tensile strength test have the highest value at a current strength of 75 A which is equal to 756.642 MPa. The lowest tensile strength test results were obtained with a tensile strength of 687.608 MPa at a current strength of 95 A. specimens with variations in current strength of 95 A have the highest value in the Vickers hardness test, with a hardness value of 281.25 HV. From the research conducted it is known that as the welding current increases there is a decrease in the value of the tensile strength. The hardness value in the heat affected zone (HAZ) area of all test specimens has the highest value, while the hardness value of weld metal (WM) and base metal (BM) has almost the same hardness value.

Influence of welding parameters on the formation of U-rib fillet welds in single-sided welding of steel bridge panels

It is difficult to reach the requirement of 80% U-rib weld penetration in the practical application of single-sided welding of steel bridge panels. Meanwhile, full penetration has to be avoided. In this study, efforts are made in order to achieve fillet welds with 80% and above penetration consistently. The effect of welding parameters on the formation of single-sided U-rib fillet welds is investigated. This work has revealed that U-rib fillet weld penetration is presenting an upward trend as the welding current increases under specific welding conditions, and full penetration was observed at the current of 325 A. With the increasing distance between the filler wire and the root of the weld, the U-rib penetration reduces. As the torch angle increases during ship position welding, the U-rib penetration will first increase and then decrease. The weld formation of flat position welding is more stable and the U-rib weld penetration has been significantly improved. The optimum U-rib weld with penetration of 84.8% is achieved under the conditions of flat position welding with 285 A welding current, 44∘ torch angle, and 2[Formula: see text]mm distance between the wire and the root.

Effect of Welding Current on Mechanical Properties and Microstructure of Aluminium AA1135 Alloys by Gas Tungsten Arc Welding (GTAW)

Aluminium alloys have a wide range of applications in the defence and aerospace industry, including for the manufacture of fuel tanks. The welding Current and type of filler metal significantly affect the microstructure formed and the mechanical strength of metal joints. This study aimed to determine the effect of the kind of filler metal (ER5356 filler metal) and welding current (140 amperes, 160 amperes, and 180 amperes) on the mechanical properties and microstructural of aluminium alloys AA1135 by the GTAW welding process. The results showed that the dendrite size increased with increasing welding current. Furthermore, the micro-hardness of the weld metal shows a decreasing trend with increasing welding current. The maximum tensile strength was obtained at a current power of 160 amperes, and all specimens failed at HAZ. The fracture surface of tensile test observations using SEM showed brittle fracture for Er5356 filler metal specimens, while on the fracture surface of the base metal tensile test specimens, it was observed to show ductile fracture. Welding with a current strength of 180 amperes has met the standard acceptance criteria because no cracks were found on the face bend or the root bend specimen

Effect of a Zn interlayer on the formation mechanism and mechanical performance of AA6061/DP590 steel resistance riveting welding

This study focuses on the forming mechanism of resistance riveting welding joints of 6061 Al alloy and DP590 steel plate and the effect of adding Zn interlayer on the mechanical properties of the joints. During the piercing stage, the rivet pierces through the Al plate, the Al plate beneath the rivet melts and reacts with the steel, with intermetallic compounds (IMC) generated. Some of the melted Al and IMCs are squeezed onto the side of the rivet. In the process of adding the Zn interlayer, the Zn is gradually incorporated into the melted Al near the rivet during the piercing process. At the welding stage, as the current is increased, the nugget diameter, peak joint load, and energy absorption values gradually increase. The failure mode of the joint changes from an interfacial fracture to pull-out fracture, eventually changing to base material pull-off, as the welding current increases. Compared to joints without Zn addition, joints with Zn addition exhibit a smaller nugget diameter, and narrower IMC layers at the interface. At a welding current of 13 kA, because the failure mode was a shear fracture of the nuggets, the peak joint load of the joints with zinc added decreased by 215 N compared to the unadded ones. On the contrary, when the current increased to 14 kA, the peak joint load of the joints was elevated by 639 N, because the IMC layer and the aluminum plate became the main load-bearing locations.

Study on the Relationship between Process Parameters and theFormation of GTAW Additive Manufacturing of TC4 Titanium Alloy Using the Response Surface Method

The geometric parameters of the deposited layer include the width, height, and penetration depth of the deposited layer. The welding current, wire feeding speed, and torch travel speed during the additive manufacturing process of TC4 titanium alloy have the greatest impact on the geometric parameters of the deposited layer. In order to study how the deposition layer width, deposition layer height, and penetration depth are affected by the welding current, wire feeding speed, and torch travel speed, this article uses Design Expert 8.0.6 software for Box−Behnken design response surface experiments. During the experimental design, the welding current, wire feeding speed, and torch travel speed are used as input variables. The deposition layer width, deposition layer height, and penetration depth are selected as the responses. We designed 17 response surface experiments that were conducted using GTAW-AM. The results show that as the welding current increases, the penetration depth and width of deposition layer gradually increase, and the deposition layer height gradually decreases. As the wire feeding speed increases, the deposition layer height and penetration depth gradually increase, and the wire feeding speed has a minimal effect on the deposition layer width. As the torch travel speed increases, the penetration depth, width and height of deposition layer gradually decrease. The response surface method experimental design can also optimize the matching of three process parameters: welding current, wire feeding speed, and torch travel speed, thereby obtaining the optimal matching range of process parameters. Within the optimized matching range of process parameters, a welding current of 90 A, a wire feeding speed of 900 mm/min, and a torch travel speed of 200.18 mm/min were selected to prepare TC4 titanium alloy thin-walled part. The microstructure of the top, middle and bottom are all basketweave structure. The α phase gradually becomes coarse from the top to the bottom. The microhardness of the top, middle, and bottom of the thin-walled parts is 362.7 HV, 352.7 HV, and 340.5 HV, respectively. The horizontal tensile strength is 926.1 MPa, with an elongation of 12.22%, and the vertical tensile strength is 938.1 MPa, with an elongation of 14.41%.

Effect of energy parameters on droplet transfer behavior and weld formation in laser-arc hybrid welding with cable-type welding wire

This paper describes the droplet transfer behavior and weld formation of laser-arc hybrid welding with cable-type welding wire (CWW). The droplet transfer behavior was photographed in real time by using a high-speed camera. The effects of energy parameters on arc morphology, droplet transfer behavior and weld formation were studied through experimental and theoretical analyses. The results show that the arc is deflected toward the laser direction, and the deflection degree increases with increasing laser power. The interaction between the laser and arc is enhanced by rotating the arc. The rotating arc enhances the interaction between plasma, the arc is more compressed and the arc volume is smaller as the welding current increases. The droplet transfer frequency increased with increasing laser power and decreased after reaching the critical value. The reaction force of metal vapor and electromagnetic force affect the droplet transfer frequency, and the maximum frequency of droplet transfer is 180.8 Hz under a laser power of 2.5 kW. The rotational force promotes molten droplet transfer and maintains the axial transition, and the welding current has a strong effect on increasing the droplet transfer frequency. The influence of laser power on weld penetration is greater than that of welding current, the weld penetration increases significantly with increasing laser power, and the cross section of the weld seam exhibits laser-arc hybrid welding characteristics.

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.

Characterization of galvanized steel-low alloy steel arc stud welded joint

This paper investigates the possibility of successfully welding a Low Alloy Steel (LAS) stud to Galvanized Steel (GS) plate.Arc Stud Welding (ASW) was performed on joining LAS studs to GS plates. Welding parameters were selected based on weld trails. The first tests of the welded joints were based on visual inspection for welding defects such as lack of fusion and undercut welding defects. The good quality should be free of these defects and have full weld reinforcement. Other weld qualifications included torque strength test, microhardness test, and microstructure examination.The LAS studs have been successfully welded to a galvanized steel plate using the arc stud welding process. Higher welding current with adjusted welding time (800 A, 0.3 s) gave full weld reinforcement, the best joint appearance, and strength. Martensite phase was detected in the weld area and heat affected zone (HAZ), affecting the joint mechanical properties. Hardness property varied across the welded joint, and maximum hardness was recorded at the HAZ at the stud side. Hardness increased with the increasing welding current. At 800 A, welding current hardness was 10% higher than at 400 and 600 A. Torque strength was affected by weld reinforcement, and 800 A gave the best weld reinforcement that produced the highest torque strength.The main research limitation is the difficulty of welding LAS studs and GS plates. In conventional welding methods, such as gas metal arc welding, it is hard to get full weld penetration due to the geometry restrictions of the joint, which results in partial weld penetration between the studs and the plates. Furthermore, the issue of zinc evaporation during welding can be reduced by the advantage of the very high welding speed (in milliseconds) of ASW that overcomes the problem of continuous welding that usually results in the formation of harmful porosities and poor weldability.In this research, galvanized steel plates were successfully welded to LAS studs using the ASW process. The welding parameters for this dissimilar welding joint were carefully selected. Microstructure changing due to the welding process was investigated. The joint mechanical properties were evaluated.

Multiobjective optimization of morphologies and performance of Q355C gas metal arc welding based on the NSGA-Ⅱ

This work studied the influence law of gas-metal-arc welding process parameters on the morphologies and performance to improve the morphologies and performance. The mixed orthogonal surfacing test was carried out by taking the preheating temperature, welding voltage, current, speed, and wire extension as GMAW process parameters. The aspect ratio decreased with increasing welding voltage, and it first increased and then decreased with increasing welding current. The hardness increased with increasing preheating temperature and welding speed and decreased with increasing welding voltage, current, and wire extension. Residual stress increased with the increased preheating temperature. In addition, it first decreased and then increased with increasing welding voltage and speed. Based on the regression model, the nondominated sorting genetic algorithm II (NSGA-II) was used for multiobjective optimization. After that, experiments were conducted to verify the noninferior solutions among the aspect ratio, hardness, and residual stress. Errors between the predicted and experimental results by the three output indices were all less than 10%, indicating the feasibility of the optimization method. The research results provide a theoretical direction for multiobjective optimization and refined applications of arc welding.

Analisis Pengujian Tarik dan Sebaran unsur pada Pengelasan Aluminium – Mild Steel menggunakan Metode Cold Metal

The technology that has been developed in recent years is the production of fusion welded plates between two different materials, for example, steel with other materials such as aluminum. Combining the two materials, aluminum and mild steel, will undoubtedly produce a material connection with good properties, for example, in a vehicle car frame. However, these two materials have different melting points, mild steel has a high melting point, and aluminum has a low melting point in the inner layer. This research aims to determine the welding results and the microstructure between aluminum plates and mild steel. The Cold Metal Transfer (CMT) welding process provides a potential method for joining dissimilar metals. In this study, various 4 mm thick aluminum alloys (Al 1100) were joined to 4 mm thick mild steel (SPHC) by CMT welding technology. It was concluded that combining aluminum alloys with mild steel using the cold metal transfer method was feasible. The optimum process variable for welding aluminum-mild steel dimensions 250 mm × 100 mm × 4 mm can be obtained with ER70S-6 wire, ArCO2 shielding gas, wire feed speed 13 m/min, and welding speed e8 mm/s.The tensile strength of the joint first increases and then decreases as the welding current increases, the highest tensile strength can reach 73.35 MPa.

Effect of plasma welding current on heat source penetration ability of plasma-GMAW hybrid welding

The weld penetration under different plasma welding currents was compared in the plasma-gas metal arc welding (GMAW) hybrid welding of aluminum alloy. When the plasma welding current was lower than 150 A, the hybrid welding penetration was greater than the sum of the single plasma welding and the single GMAW penetration. When the plasma welding current reached 130 A, with the increase of the plasma welding current, the advantage of the weld penetration of the hybrid welding was gradually weakened, compared with that of the single welding. The above change mechanism is revealed from heat source energy distribution and molten pool stress. The results show that when the plasma welding current is lower than 110 A, the area of the high-temperature region in the arc zone of GMAW in the hybrid welding increases, compared with that in the single GMAW. The trend of arc energy transfer to the penetration direction increases under the action of arc pressure, arc shear force, electromagnetic force, and droplet impact. With the increase of plasma welding current, the high-temperature area of the GMAW arc first increases and then decreases. When the plasma current reaches 130 A, the effect of arc pressure, arc shear force, electromagnetic force, and droplet impact on increasing the penetration begins to weaken.

Effect of electrode negativity ratio and heat input on bead and arc characteristics in submerged arc welding

The effect of electrode negativity (EN) ratio, current and welding speed on bead profile and arc stability in case of constant current square wave power source were investigated by conducting bead on plate (BOP) welding experiments on API X80 steel. In addition to this, effects of heat input on prior austenite grain (PAG) size, microstructure and hardness of coarse grain heat affected zone (CGHAZ) were also studied. Deleterious hump angle created due to EN ratio variation, decreased with increase in EN ratio and welding current. Average PAG size and spacing between bainite laths increased from 17.09 µm to 62.66 µm and 0.67 µm to 50 µm respectively with increase in heat input from 0.69 kJ/mm to 3.6 kJ/mm, which altered CGHAZ hardness. Arc stability and metal transfer mode for different EN ratios and currents were analyzed by means of probability density distribution (PDD) graphs of current and voltage transients recorded using a digital storage oscilloscope. PDD graph show better arc stability at higher currents and during the electrode positive (EP) part of current waveform.

Study on the Molten Pool Fluid Behavior of PAW-Cable-Type Seven-Wire GMAW Hybrid Welding

Plasma arc welding (PAW)-cable-type seven-wire GMAW (gas metal arc welding) hybrid welding is known as a high-efficiency welding combining plasma arc, GMAW arc and cable-type welding wire. In this study, numerical simulation via Fluent of the molten pool temperature field and flow field and experimental verification were conducted on Q235 thin plate hybrid welding with cable-type wire to explore molten pool fluid behavior. The simulation results show that keyholes form in the molten pool due to the strong penetration ability of a plasma arc and then the evolved pores by the surface tension float out of the molten pool. When the GMAW welding current increases, both the length and width of the weld pool enlarge, the weld reinforcement increases and the flow rate of molten metal in the weld pool also speeds up. While the PAW current increases, the weld pool length also increases and the molten metal in the weld pool significantly flows faster, but the weld reinforcement decreases. When the welding speed increases, the weld pool length and fusion depth decrease, but the reinforcement will first increase and then decrease. The experimental results are in strong agreement with the simulation results. It shows that the numerical analysis model established in this paper is accurate, laying a certain theoretical foundation for the popularization of PAW-cable-type seven-wire GMAW hybrid welding.

Dependency of arc efficiency on welding current in gas metal arc welding

Arc efficiency of gas metal arc welding was measured in changing welding current. Increasing welding current, arc efficiency showed convex curve. Estimating amount of heat transferred by metal droplets, it was concluded that increase of arc efficiency in the welding current less than 186 A was caused by heat of metal transfer, while decrease in the welding current more than 186 A was caused by overwhelming arc radiation.

Resistance spot welding of a thin 0.7 mm EN10130: DC04 material onto a thicker 2.4 mm 817M40 engineering steel

The effects of welding current, electrode force, and welding time in a resistance spot weld were studied to investigate the effectiveness of welded joints between a thin EN10130: DC04 material and a thicker 817M40 part, through analysis of the microstructural and mechanical properties. All welded specimens were subjected to tensile testing at room temperature (25°C) and sub-zero temperature (-46°C) to test the strength of the welded joints. No full button failure was observed at either room temperature or sub-zero temperature after optimization of the weldng parameters. The fusion zone was observed to consist mainly of martensitic phase, due to rapid quenching, while the HAZ was composed of clusters of martensite in a ferrite and bainite matrix. The base 817M40 metal remained fully ferritic after welding. The hardness was found to increase with increasing welding current. An increase in nugget size, indicating good fusion of the weld, was observed with an increase in the welding current.

Resistance element welding of 7075 aluminum alloy to Ti6Al4V titanium alloy

In this paper, Al/Ti joints are produced by resistance element welding (REW). A hole is made in the Al sheet and a welding element (Ti6Al4V rivet) is inserted into the hole followed by resistance welding to create a metallurgical bond between the Ti rivet and Ti sheet. The mechanical properties, fracture mode, microstructure, and hardness distribution of the joints are analyzed. The REW joints show higher tensile-shear load and energy absorption than present riveted joints. The maximum peak load and energy absorption of the REW joints improved with the increasing of rivet diameter. The failure mode for Al/Ti REW joints transits from interfacial to pullout mode, and then to fully pullout mode with increasing welding current. The nugget microstructure mainly consists of acicular α′ phase martensite. A discontinuous intermetallic compound layer is formed at the Ti/Al interface, and it consists of TiAl2, TiAl, or a mixture thereof.

Effect of filler and autogenous welding on microstructure, mechanical and corrosion properties of low nickel Cr-Mn ASS

ABSTRACT This experimental study investigates the effects of welding low nickel Cr-Mn austenitic stainless steel with gas tungsten arc welding process with and without filler (autogenous) weld by varying the welding currents (120A, 130A and 140A). The microstructural examination of weld has been carried out with optical microscope and mechanical properties with Vickers microhardness and tensile tester. The corrosion behaviour of the welded joints are analysed by double loop electrochemical potentio-kinetic reactivation test to obtain degree of sensitisation. The microstructural examination of welded joints revealed that, as the welding current increases, the inter-dendritic spacing as well as the dendrite size increases. The tensile strength and hardness decrease with increasing welding current for 308 L filler and autogenous weld. The degree of sensitisation increases with increasing welding current for both the welds. The results reveal that the autogenous welds have higher tensile strength, higher hardness and lower degree of sensitisation as compared to welds with 308 L filler.

Determination of emission of iron oxides from the welding process on the basis of mathematical models

Oxygen in metals is most often present in the form of oxides, including: FeO, Fe2O3, Fe3O4. The complexity of the welding process means that oxygen compounds can enter both the liquid metal and the atmosphere, causing negative effects. A welder is exposed to harmful emission of oxides entering the human body through the respiratory system or pores in the skin. The essence of the problem is so serious that standards for air purity and determination of amount of oxides at workplaces have been introduced. The article presents the results of research on the influence of the welding current intensity on the emission of air pollutants (in particular the emission of iron oxides) of the inhalable and respirable fractions. The bench tests were carried out on the basis of the applicable standards for air quality at welding stations. Based on the test results, on the basis of the R program, mathematical models of the emission of iron oxides generated during the welding process were developed. It was observed that with the increase of the welding current, the average value of the emission of iron oxides – both the inhalable and respirable fractions – increases. For both fractions, it was also noted that the model values ​​are closer to the values measured in the model No. 1.