Pulsed MIG Welding Research Articles

Evaluation Method of Magnetic Field Stability for Robotic Arc Welding Based on Sample Entropy and Probability Distribution

In this study, we analyzed the arc magnetic field to assess the stability of the arc welding process, particularly in robotic welding where direct measurement of welding current is challenging, such as under water. The characteristics of the magnetic field were evaluated based on low-frequency fluctuations and the symmetry of the signals. We used double-wire pulsed MIG welding for our experiments, employing Q235 steel with an 8.0 mm thickness as the material. Key parameters included an average voltage of 19.8 V, current of 120 A, and a wire feeding speed of 3.3 m/min. Our spectral analysis revealed significant correlations between welding stability and factors such as the direct current (DC) component and the peak power spectral density (PSD) frequency. To quantify this relationship, we introduced a novel approach using sample entropy and mix sample entropy (MSE) as new evaluation metrics. This method achieved a notable accuracy of 88%, demonstrating its effectiveness in assessing the stability of the robotic welding process.

Process Parameter Optimization and Metallurgical Characterization in Double Pulse MIG Welding of SS 304 H

Process Parameter Optimization and Metallurgical Characterization in Double Pulse MIG Welding of SS 304 H

Single-pulse MIG welded Perform 700 steel joints with various welding parameters

In this work, Perform 700 steel sheets with 5-mm thickness were welded with single pulse MIG welding method with different welding currents and welding speeds. The welded specimens were subjected to tensile tests, hardness measurements and microstructural observations. According to the results, the heat input has an important role in tensile strength of the joint. The maximum tensile strength was obtained as 594.75 MPa at 140A welding current and 450 mm/min welding speed. The tensile specimens were always separated between fusion zone and heat affected zone. The heat affected zones have exhibited tempered martensitic structure. The tempering effect have increased the sizes of the martensitic structure; therefore, the hardness was considerably increased. However, the fusion zone, which was consisted of bainitic structure inside the ferrite matrix, was exhibited soft and ductile behavior. The boundary of soft fusion zone and hard heat affected zone formed the weakest point through the joint.

Effect mechanism of arc oscillation on microstructure and mechanical performance of SUS304 weld seams manufactured by local dry underwater double pulsed MIG welding

An innovative local dry underwater double pulsed MIG (LDU-DPMIG) technique was successfully applied to fabricate SUS304 weld seams, in which the stirring effect on the molten pool was realized via a double pulsed current waveform. The weld formation, phase morphology and distribution, grain structure characteristics, microhardness, and tensile properties of underwater weld seams were comprehensively analyzed in this study, especially the mechanism differences between local dry underwater single pulsed MIG (LDU-SPMIG) and LDU-DPMIG were revealed. The results demonstrated that the stirring effect caused by arc oscillation contributed to the enhancement of the molten pool fluidity during the solidification process, which effectively facilitated the smooth elements allocations between austenite and ferrite and the evolution of δ-ferrite phase structure from skeleton to lath. In addition, the grain structure in the DPMIG weld centre transformed from slender columnar dendrites to fine equiaxed dendrites. Due to the pronounced stirring effects in uniform composition distribution, ferrite morphology evolution, grain refinement, and increased twin activity, DPMIG weld seams exhibited an attractive enhancement in weld mechanical performances, with the optimal low frequency of 3 Hz, the average microhardness, ultimate tensile strength, and elongation enhanced by the highest 18.1%, 8.9%, and 16.3% compared with SPMIG weld seam. These results are expected to offer a novel approach to regulate and control the microstructure and mechanical performance of underwater weld seams and facilitate the application of LDU-DPMIG in ocean engineering equipment.

Experimental studies on automated DC pulsed MIG welding of Monel 400 sheets

ABSTRACTHot-rolled Monel 400 sheets of 2 mm thickness were effectively welded by the automated DC-pulsed gas metal arc welding (DC-pulsed GMAW) process using ERNiCu-7 (NA60) filler. An L9 array has been used in this work to obtain optimal robotic welding parameters to achieve better weld quality. The weldments was subjected to microstructural examinations using optical microscopy. The chemical compounds and elements of the weldments were determined using X-ray diffraction and energy-dispersive analyses. The microhardness and tensile properties of the weldments were evaluated. The corrosion behavior of the base metal and weldments was estimated in service environments by exposing them to a 3.5% NaCl solution using a potentiodynamic polarization method. The weld zone has the highest microhardness value of 154 HV. Monel 400 weldments have lower joint strength and elongation than the base metal. In addition, weldments have a higher corrosion rate (201.1 mm/yr) than base metal (55.64 mm/yr).

MECHANICAL AND METALLURGICAL CHARACTERISATION OF DOUBLE PULSE MIG WELDED IN 617- SS 304 H

ABSTRACT This work attempts to study the mechanical and metallurgical properties of dissimilar welded IN (Inconel) 617-SS (Stainless steel) 304 H plates. Welding was carried out using the Double Pulse MIG Welding Process (DP-MIG) with two different heat inputs, namely 412 J/mm and 452 J/mm. The presence of chromium-rich carbides Cr23C6 helped in strengthening the weld. The tensile strength of the weld made at 452 J/mm was 22% more than that of the weld made at 412 J/mm. Similarly, the weld hardness at 452 J/mm was 8% greater than the weld strength at 412 J/mm. The impact strength did not change significantly with respect to the heat input. Weld made at lower heat input (412 J/mm) had a lack of sidewall fusion. Lower frequency and amplitude contributed to poor heat distribution, leading to a lack of sidewall fusion.

Experimental evaluation of longitudinal tensile properties of ferritic stainless-steel weldment joined by metal inert gas, pulse metal inert gas, and tungsten inert gas welding

In this work, ferritic stainless steel (FSS) weldments were prepared by tungsten inert gas (TIG), metal inert gas (MIG), and pulsed-MIG welding. Pure argon and a mixture of argon + 2% oxygen were utilized as shielding gas in each type of welding. The FSS (ER430) and austenitic stainless steel (ASS) (ER309L) wires were used as filler consumable wires during all the three types of welding. The effects of varying welding processes, shielding gases, and consumable electrodes on the longitudinal tensile properties of weldments were investigated. The universal tensile testing machine was used to evaluate longitudinal ultimate tensile strength and percentage elongation experimentally in each case. The maximum tensile strength of FSS weldment was obtained in the case of (Ar + 2% O2) mixture of shielding gas and ASS filler wire in each welding process. Heat treatment was also carried out for samples prepared by MIG and TIG welding. The reduction in tensile strength and enhancement in percentage elongation was observed for both MIG and TIG welding after heat treatment.

Effect of pulse current on droplet transfer behavior and weld formation of 304 stainless steel in local dry underwater pulse MIG welding

Effect of pulse current on droplet transfer behavior and weld formation of 304 stainless steel in local dry underwater pulse MIG welding

Investigations of heat source models in transient thermal simulation of pulsed MIG welding of AA6061-T6 thin sheet

The automobile and aviation industries are exhaustively working on weight reduction by replacing steel with aluminium alloy. However, joining the aluminium alloy body panel is remain a big challenge because of the inherent properties of aluminium. The dynamic behaviour of arc plasma in the pulsed MIG welding process is a multifaceted heat mass transfer phenomenon involving chemical, electro-magnetic, and fluid dynamics. Numerical simulation using FEA techniques are greatly helpful in understanding responses of weld bead and material behaviour. Simultaneously it reduces time and cost consuming experimental trial and error approach. The approximation of the welding arc heat source is paramount for precise prediction in the welding process simulation model. The article focuses on the comparison, suitability and effects of various moving heat source models by developing the transient thermal simulation of pulsed MIG welding of 1mm thick AA6061-T6 sheet in ANSYS workbench. Moving heat source models were developed as ANSYS APDL command subroutine. It is observed that for 1mm thin sheets Gaussian surface heat source model is also valid. The difference in temperature field is not prominent in comparison with Goldak’s double ellipsoidal heat source model.

Evolutionary Algorithm On Cold Metal Transfer Process For Feature Extraction

In order to achieve the desired bead geometry in a welding operation it is of prime importance to select suitable process parameters. In this research, pulsed MIG welding of 316L austenitic stainless steel is perforated and its bead geometry is studied, such as penetration depth bead width and height of reinforcement. The optimization approach based on the Genetic Algorithm (GA) is implemented to ensure the optimal combination of process variables and bead geometry. Regression model are initially generated by using experimental data. GA is then generated to optimize the parameters of the method and bead geometry parameters by minimizing the objective function based on the least square error. Pulsed MIG welded parameters was experimentally tested by microscopic analysis and EDAX analysis for three sample sets. The finding suggest that expected and experimental values are close in agreement. Finally, the effect of the welding current on the elemental composition is seen. The research shows that in the GA based method, the rate of convergence is faster.

Progress in the arc plasma temperature measurement and its finite element analysis in pulsed MIG welding process

The article focuses on the state of the art review of progress in the arc plasma temperature measurement, a lesser-explored area of pulsed metal inert gas welding because of technological and economic constraints. However, investigation of the arc plasma temperature is paramount for precise prediction in welding process simulation models. The dynamic behavior of arc plasma in the pulsed MIG welding process is a multifaceted heat mass transfer phenomenon involving chemical, electro-magnetic, and fluid dynamics.In the pulsed MIG welding process thermal, mechanical, and electrical phenomenon co-exists and results in the formation of all four states of matter in a very small fusion sphere. The paper throws light on the latest investigations on the importance of precise measurement of arc plasma temperature, techniques used for measurement of the arc plasma, and challenges associated with pulsed MIG welding. Moreover, unanswered characteristics of the welding fusion sphere with future directions are discussed in the challenges section. It will serve as a guide to researchers and industry for developing better insight for performing pulsed MIG welding, developing accurate numerical models of pulsed MIG welding, and will also provide sufficient base to focus on thrust area of pulsed MIG welding.

Practical Investigation of FSS (AISI 430) Weldments Welded by Pulse MIG Welding Process

Ferritic stainless steels are iron-chromium alloys having chromium content usually in the range of 10.5–27%. In these steels the predominant metallurgical phase present is ferrite. These steels are Fe-Cr-C alloys with sufficient chromium or chromium plus other ferrite stabilizer, such as aluminium, niobium, molybdenum, titanium, used to inhibit the formation of austenite phase on heating. Ferritic stainless steel (FSS) is generally considered to have poor weldability when compared to austenitic stainless steel (ASS) but has recently drawn greater attention owing to their lower costs and better resistance to stress corrosion resistance than austenitic stainless steel. Ferritic stainless steels have been widely used in vessels, vehicles, household appliances, kitchen equipments and building decoration because of its excellent stress corrosion and spot corrosion resistance addition to good strength. Because it does not contain nickel, it is a cheaper alternative of austenitic stainless steel. In this work weldments of FSS welded by pulse MIG welding using argon as a shielding gas were investigated. The austenitic stainless steel (ER309L) and ferritic stainless steel (ER430) electrode wires were used to prepare the weldments. To obtain a good welded joint the welding process parameters were experimentally optimised. The microstructures and mechanical properties of the prepared weldments were investigated. In the weldment welded by austenitic stainless steel electrode wire dendritic austenitic phase was observed in the weld metal zone. In heat affected zone intragranular carbide precipitation and grain boundary martensite were observed. In case of weldments welded by ferritic stainless steel electrode wire coarse grains were formed in weld metal zone and heat affected zone. Grain boundary martensite, ferrite and intragranular carbide precipitation were found in weld metal zone and heat affected zone. Impact strength of the weldments welded by austenitic stainless steel electrode wire was found higher due to formation of austenite phase in the weld metal zone. Impact strength of the weldments welded by ferritic stainless steel electrode wire was found very low due to formation of coarse grain and martensite in the weld metal zone. The ultimate tensile strength and percentage elongation of the weldments welded by austenitic stainless steel electrode wire were found higher than the weldments welded by ferritic stainless steel electrode wire. Hence weldments of ferritic stainless steel having superior mechanical properties will be obtained by using austenitic stainless steel electrode wire. During the tensile test the specimens were broken outside the welded joint (in base metal) which confirms the good quality of the joints

Time frequency feature extraction of the arc energy for quality detection of the aluminum alloy double pulse MIG welding

Time frequency feature extraction of the arc energy for quality detection of the aluminum alloy double pulse MIG welding

Investigations on weld bead geometry and microstructure in CMT, MIG pulse synergic and MIG welding of AA6061-T6

This research paper focuses on a comparative study on weld bead geometries of three different welding techniques: Cold Metal Transfer (CMT), Metal Inert Gas Pulse Synergic (MIG P) and MIG Manual Standard (MIG M). Bead-on-plate tests were performed using ER4043 (AlSi5%) as a filler material on the 3.18 mm thick plates of AA6061-T6. Current (80 A, 100 A and 120 A) and welding speed (7.5, 10.5 and 13.5 mm sec−1) were used as input process parameters while shielding gas flow rate and contact tip to workpiece distance (CTWD) were maintained constant as 15 l min−1 and 10 mm respectively. The weld beads processed by all the three techniques are compared by analysing the weld bead geometry. Microstructural characterization is carried out using optical microscopy and Field Emission Scanning Electron Microscope (FESEM). CMT has high dilution and penetration with low heat input. Compared to MIG Pulse Synergic and MIG Manual, CMT shows a drastic reduction in residual stresses. A good amount of penetration and dilution with low heat input is necessitated for better joint efficiency.

Comparison of Al-Zn-Mg Alloy P-MIG Welded Joints Filled with Different Wires

Abstract Three kinds of welding filler wires, named ER5356, ER5087 and ER4043, were used to joint 12 mm thick Al-Zn-Mg alloy plate by the pulsed MIG(P-MIG) welding. The microstructure and mechanical properties of the joints were analyzed and compared. The results showed that the average tensile strengths of the joints filled with ER5356, ER5087 and ER4043 were 294 MPa, 313 MPa and 237 MPa, respectively, and the average elongations were 7.9%, 7.6% and 1.6%, respectively. All the joints’s fracture locations were near the fusion boundary. The microhardness test showed that the locations of the lowest hardness were all in the center of cross section. The results revealed that the weld filler by ER5087 was consist of more columnar crystals of larger grain size, while the weld filled by ER5356 was consist of more equiaxed grains of smaller grain size. The microstructure of the weld by ER4043 was typical eutectic dendrites structure.

Effect of Double Pulse MIG Welding on Porosity Formation on Aluminium 5083 Fillet Joint

In this article, parameters of Double-Pulse Metal Inert Gas Welding (DP-MIG) was used for minimising a porosity formation in a T-joint fillet weld. AA5083-H112 aluminium alloy (Non-heat treatable series) with the plate thickness of 10 millimetres is base metal for this study. Welding consumables were filler wire ER5356 with a diameter of 1.2 millimetres and shielded by industrial argon gas. Three majorities parameter of DP-MIG were Delta wire feed (m/min), Frequency (Hz) and Duty cycle (%). Measurable signal current pattern and opened porosity on the fractured surface were couple observed to study their relationships. An appropriate image processing technique was employed to quantitative measuring and calculating a size grouping area of several opened porosities overall weld length, precisely. The result found that the optimal was used a low-level of Delta wire feed of 0.8 m/min, a high-level of a frequency of 5.0 Hz, a mid-level of the duty cycle 30 % and a high travel speed 60 cm/min could minimise the porosity formation with complete penetration.

Interleaved Parallel Two-Transistor Forward Converters for Pulsed MIG Welding

In this paper, a pulsed MIG welding power system based on the interleaved paraller two-transistor forward converter is studied. The hardware structure principle diagram and overall control scheme of the system are analyzed. This paper focuses on the analysis of the small-signal model of the main circuit, and establishes the transfer function of the arc-length loop and the current loop respectively, and designs a double closed-loop controller. Experiments were carried out according to the paper’s scheme. The experimental waveforms prove that the power system scheme of this paper is correct and feasible.

Tandem metal inert gas process for high productivity wire arc additive manufacturing in stainless steel

This study investigates the feasibility of achieving high deposition rate using wire + arc additive manufacturing in stainless steel to reduce lead time and cost of manufacturing. The pulse MIG welding technique with a tandem torch was used for depositing martensitic stainless steel 17-4 pH. The mechanical and metallurgical properties of the manufactured component were analysed to evaluate the limitations and the extent to which the rate of deposition reaches a maximum without any failure or defect being evident in the manufactured component. Deposition rate of 9.5 kg/h was achieved. The hardness was matched for the as deposited condition.

Research on Arc Length Control Technology of Double Closed-loop for Pulsed MIG Welding

This paper presents a pulsed MIG welding arc length control method based on fuzzy control, which can better realize the dynamic control of arc and ensure arc length stability. In this system, a double-closed-loop control scheme is proposed, a variable-parameter PI control method is used, and a two-dimensional fuzzy controller of an arc-length loop is designed. Both the simulation and the experimental results show that when the distance between the welding gun and the workpiece changes, the arc length can reach a new balance and stable state after 9 pulse periods. The arc length control technology of double closed-loop for pulsed MIG welding is verified feasible in this paper.

Effect of ultrasonic pattern on weld appearance and droplet transfer in ultrasonic assisted MIG welding process

The effect of continuous ultrasonic and pulsed ultrasonic on weld appearance and droplet transfer in ultrasonic assisted MIG welding was investigated by exploiting optical microscope and high-speed imaging. Meanwhile, the influence of eight different frequencies on welding quality of the pulsed ultrasonic assisted MIG welding (PU-MIG) was studied. The results showed that the ultrasonic assisted MIG welding process was more stable than conventional MIG welding process. Compared with the conventional MIG, the U-MIG weld penetrations increased obviously under the same welding parameters and the largest weld penetration obtained by PU-MIG with a frequency of 120 Hz. The high speed camera images showed that the droplet transfer cycle and arc length of U-MIG were remarkably improved. The arc compression was the main reason for the increasing of the weld penetration and the droplet transfer cycle. Finally, porosity formation mechanism of aluminum alloy in ultrasonic assisted MIG welding was discussed.