Welding Wire Research Articles

Control of weld distortion through in-situ preheating of weld filler wire

ABSTRACT The present study deals with a new technique for controlling the weld-induced distortion. This developed technique involves in-situ preheating of welding filler wire before it emerges from the contact tube. Welding filler wire preheating was carried out using an external constant current power source and a specially designed welding torch. Weld beads were deposited on 3.0 mm low carbon steel sheet using a bead on plate technique with different preheat values of welding filler wire by the submerged arc welding process. Electrical signals were recorded to analyze the effect of welding filler wire preheating on arc characteristics. Probability density distribution (PDD) curves from electrical signals indicate that with the rise in preheat value, welding current decreases and results in stable arc characteristics. An increase in preheat value also reduces the longitudinal bending distortion of the sheet. The maximum reduction in the longitudinal bending distortion of the sheet (~53%) was obtained at the maximum preheat value of 200 Ampere.

The Ultimate Load Estimation of Welded Joints of High-Strength Steels subject to Mechanical and Geometric Heterogeneity

In this paper we consider the problems arising in the numerical estimation of the ultimate load of welded joints of high-strength steels with slight hardening. The stress concentrator in the transition node from the deposited to the base metal is modeled based on the example of welding a roller wire on a plate made of high-strength steel. The use of welding wire with a yield point lower than that of the base metal allowed to simulate areas of the welded joint with heterogeneous mechanical properties. The geometry of three areas of the welded joint is studied, i.e. weld metal, heat-affected zone (HAZ) and the base metal. Mechanical properties of all three areas are determined by calculation and experimentally. For this purpose, it is proposed to consider the material in all sections as ideally elastic-plastic, and the yield strength is uniquely associated with the hardness in the indentation zone (a Rockwell diamond cone is used). Calculations of the inelastic indentation process by the finite element method (FEM) in axis-symmetric formulation allowed obtaining a linear relationship between the hardness and the yield strength with a coefficient of 0.418. Tests at a quasi-static three-point bend (with stretching in the surfacing area) were carried out on sample beams cut perpendicular to the direction of welding. The “force-deflection” diagrams are obtained and compared with the calculated curves (FEM in a three-dimensional formulation with an explicit consideration of the complex configuration of all sections and different yield stress in the areas determined by local hardness values). There is a good agreement between the calculated and experimental ultimate loads. The proposed method of the three-stage study (determination of local hardness, yield strength in the areas and the ultimate load) can be effectively used to assess the ultimate loads of the welded joints due to the low parametricity of the proposed models of materials inelastic deformation in areas for which it is impossible to manufacture standard samples for the study of mechanical properties. The experimental study of the strengthening effect of the seam with a stress concentrator in the form of an angle of 90 degrees on the value of the ultimate bending load showed that the removal of the deposited metal does not lead to an increase in the ultimate load of the welded joint when using the welding wire of low-carbon high-plastic steel.

Dissimilar unbeveled butt joints of AA6061 to S235 structural steel by means of standard single beam fiber laser welding-brazing

Abstract The design of parts involving the combination of different materials has gained much attention in recent years as a strategy to achieve weight reduction. Joining of dissimilar materials has become a necessity to produce such parts. However, obtaining dissimilar welds showing high mechanical performance usually takes complex, expensive and time-consuming approaches. In this study, an affordable welding approach is proposed to join 6061 aluminum alloy to S235 structural steel, based on a single laser beam, on unbeveled square butt joints, and on the combination of welding wire and preplaced Al-Si powder. The relation between welding parameters and imperfections formation is studied by using a combined parameters analysis, and thorough microstructural and mechanical characterization are performed. The application of AlSi5 wire in combination with AlSi12 powder led to crack-free welds showing homogeneous 3 ± 1 μm-thick intermetallic compound (IMC) layer, composed of Fe2Al5, Fe4Al13 and Fe4Al17.5Si1.5 intermetallics. Transverse tensile tests showed that ultimate tensile strength of joints was as high as 169 MPa, which is above the minimum value established by international standards on AA6061 welds and comparable to the values obtained by other authors’ dissimilar welds by using more complex and expensive welding approaches. The IMC layer showed 11.2 ± 0.7 GPa hardness and 257 ± 24 GPa modulus of elasticity. Both properties are much higher than the base materials ones, and are in agreement with the mechanical behavior seen under tensile testing.

Influence of shape of weld toe and hardness of weld metal on fatigue properties in GMA welded fillet lap joint of UHSS sheet

ABSTRACT This study aims to clarify the influence of shape around weld toe and hardness of weld metal on fatigue crack life in fillet lap joints for automotive chassis elements. Gas metal arc (GMA) welding was performed using 980 MPa class hot rolled steel sheet as the test material. The shape around weld toe and hardness of weld metal were changed by the combination of the shield gas composition and the welding wire. The smoothing of the weld toe significantly improved the fatigue life compared to the hardened weld metal. The total fatigue life was separated into crack initiation life and crack propagation life by measuring the decreasing ratio in the stiffness of the specimen during the fatigue test. Then, the effect of smoothing the weld toe and hardening the weld metal on each life was examined. The changes in the propagating crack front shape and the propagation rate during fatigue test were examined by the beach mark technique. As a result, it was suggested that the smoothing of weld toe improves not only the crack initiation life but also the propagation life by delaying the crack propagation rate in the early stage of crack propagation. The mechanism of retardation of crack propagation rate due to smoothing of weld toe was discussed from the viewpoint of crack shape and aspect ratio.

Lack of fusion at the electrical contact welding of steel wires

ABSTRACT Lack of penetration at the joint of the main and filler metals as well as at adjoining weld beads can be a significant disadvantage in restoring worn parts by electrocontact welding when wires are welded in the helical curve. The best way to improve restoration quality is to find a better welding condition. It is possible to meet a lack of penetration by additional force impact on welding material by stretching the wire at welding. A new way to two filler wires simultaneously by stretching them with different forces is recommended.

Multiscale modelling of microstructure, micro-segregation, and local mechanical properties of Al-Cu alloys in wire and arc additive manufacturing

Abstract Wire and Arc Additive Manufacturing (WAAM) is a combination of welding and AM technologies and uses an electric arc as the heat source to melt welding wire. The mechanical properties of WAAM components are greatly dependent on the solidification behavior and microstructure. In this paper, a model composed of a macroscopic finite element (FE) model combined with a microscopic phase field (PF) model was constructed to investigate the Al alloy microstructure evolution during WAAM. First, the FE model was implemented to calculate the temperature gradient and solidification speed under different processing parameters. These results were then fed into the PF model to simulate the microstructure and concentration field of chemical compositions. The simulated results indicate that the moving speed of the substrate has a pronounced impact on the primary dendrite arm spacing (PDAS), which grew significantly as the moving speed increased, while the PDAS decreased slightly upon increasing the electric current. Furthermore, the solute distribution analysis showed that micro-segregation formed during the solidification process, and that current and substrate speed had evident impact on the micro-segregation ratio. Finally, metallographic experiments, energy-dispersive spectrometer analysis for element distribution, and miniature tensile tests were conducted on the specimens to validate the PF simulated results and obtain the relationship between process parameters and mechanical properties.

Prediction of Surface Wrinkle Defect of Welding Wire Steel ER70S-6 in Hot Bar Rolling Process Using Finite Element Method and Experiments

High quality products are demanded due to increasingly fierce market competition. In this paper, the generation of surface wrinkle defect of welding wire steel ER70S-6 was studied by the combination of the experimental method and finite element simulation. Firstly, a thermal compression test was conducted on the Gleeble-3500 thermosimulator under different strain rates and temperatures and a strain dependent Arrhenius-type constitutive function was employed to fit the flow stress–strain curves obtained from the experiments. Then, the elastoplastic constitutive relationship was implemented using radial return mapping algorithm by means of the user subroutine VUMAT of Abaqus/Explicit. A new instability criterion was proposed to predict the possibility of the surface wrinkle defect during the multipass hot bar rolling process. In order to verify the reliability of the finite element model of the six-pass continuous rolling process, the simulated results were compared with experimental data. Finally, the effects of groove width and groove radius on the billet were investigated by the orthogonal test method, and the friction coefficient and rolling temperature. The results show that the groove width and groove radius are key factors to suppress the surface wrinkle defect. Decreasing the groove width can be beneficial for improving the surface quality and reducing the fillet radius. The optimized combination of the rolling process parameters was further applied in an industrial test and the surface quality of the billet was greatly improved.

Use of barium-strontium modifier for the manufacturing of welding flux based on silicomanganese slag

The possibility of using a barium-strontium modifier as a gasprotective and refining additive for welding the fluxes based on crushed slag from the production of ferrosilicomanganese is presented. The barium-strontium modifier BSK-2 produced by JSC “NPK Metalltekhnoprom” according to TU 1717-001-75073896–2005 was used as a material for the study. The base of the welding flux was silicomanganese slag produced by the West Siberian Electrometallurgical Plant. The research work on new welding fluxes and flux-additives was carried out using the equipment of the Scientific and Production Center “Welding Processes and Technologies” and the Center for Collective Use “Materials Science”. The use of barium-strontium flux additive was carried out in two ways. In the first option, the flux-additive was made by grinding barium-strontium to a dust-like fraction of less than 0.2 mm with further mixing with liquid sodium glass, drying in a furnace, crushing and separating a fraction of 0.45 – 3.00 mm. In the second option, the flux additive was used in the form of dust with a fraction of less than 0.2 mm. The additives were mixed at a ratio of 2 – 10 % of mass of the slag produced by silicomanganese. Surfacing of the samples was carried out with a welding wire of the sv-08GA grade on a substrate of steel grade 09G2S with a thickness of 20 mm. Quality of the deposited metal was studied, the chemical compositions (deposited layers, slag crusts, the used flux) were investigated by X-ray fluorescence method on XRF-1800 spectrometer and by atomic emission method on DFS-71 spectrometer. The degree of contamination with non-metallic inclusions (non-deforming silicates, point oxides, sulfides) was studied using OLYMPUS GX-51 optical microscope in the magnification range from 100 to 1000. The laboratory studies on the surfacing of steel samples have shown that due to introduction of a flux additive made from barium-strontium modifier, the metal is refined, and the concentration of sulfur and phosphorus decreases. The use of a mixture of a barium-strontium modifier with liquid glass as an additive is preferable to the use of an additive in the form of a dust. It was revealed that the best samples from the point of view of the degree of contamination of the deposited metal with nonmetallic inclusions are samples made using no more than 8 % of barium-strontium flux additive.

The Microstructure and Mechanical Properties of Dual-Spot Laser Welded-Brazed Ti/Al Butt Joints with Different Groove Shapes.

Laser welding-brazing was performed to join Ti and Al together. The dual-spot laser beam mode was selected as the heat source in this study. Ti-6Al-4V and 6061-T6 Al alloys were selected as the experimental materials. Al-12Si welding wire was selected as the filler material. The effect of groove shape on the weld appearance, microstructure, temperature field, and mechanical performance of Ti/Al welded-brazed butt joints was investigated. The interfacial intermetallic compound (IMC) layer at the Ti/Weld brazing interface was inhomogeneous in joints with I-shaped and Y-shaped grooves. In Ti/Al joints with V-shaped grooves, the homogeneity of temperature field and IMC layer was improved, and the maximum thickness difference of IMC layer was only 0.20 μm. Nano-sized granular Ti7Al5Si12, Ti5Si3, and Ti(Al,Si)3 constituted the IMCs. The tensile strength of Ti/Al joints with V-shaped grooves was the highest at 187 MPa. The fracture mode transformed from brittle fractures located in the IMC layer to ductile fractures located in the Al base metal, which could be attributed to the improvement of the IMC layer at the brazing interface.

Recovery and Recycling Silica Flux in Submerged Arc Welding – Acceptable Properties and Economical Correlation

This research aims at optimum utilization of waste recycled submerged arc welding slag along with virgin flux in place of pure virgin flux without compromising the quality of welding and effective waste reduction. The related quality aspects, determination of quantum of recycled slag to be used are evaluated through suitable experimentation. The application, process parameters, welding parameters, parent material and filler wires are also changing in line with the job order. In such a dynamic environment weld economy has to be inbuilt through proper mechanism. A suitable mechanism involving optimum usage of spent slag with virgin flux will be ideal in such a dynamic environment An attempt has been made to introduce the waste recycled slag along with virgin flux during Submerged Arc Welding (SAW) of low carbon steel with suitable wire and optimum welding parameters. Varying weight percentage (20, 30,40 & 50 wt.%) of waste slags were mixed and submerged arc welding was carried out; Mechanical testing, Radiography, Ultrasonic tests were employed to ascertain the quality and arrived the optimum mixture of slag and virgin flux. Results revealed that usage of waste slag between 20 and 30 wt.% showcased optimum tensile strength, impact strength, hardness and reduction of cost. However any deviation from the optimum level of recycled slag with virgin flux will deviate from optimum level of quality or profit.

Investigation of the microstructure and mechanical performance of bimetal components fabricated using CMT-based wire arc additive manufacturing

Traditionally, wear-resistant components are manufactured by cladding hard facing material on the base metal. This production process is typically complicated, expensive, and time-consuming. This study proposes a method of fabricating components with high wear resistance requirements utilizing cold metal transfer based wire and arc additive manufacturing with hard facing welding wire as the consumable material. Thin-walled and block components were manufactured by depositing a combination of a low alloy steel, ER80S-G, and a hard facing material, MF6–55GP. Microstructure characterization and mechanical properties (hardness, tensile and Block-on-Ring wear test) were performed. The results revealed that the ER80S-G/MF6–55GP bimetal components were able to be fused with no detectable defects near the border. As the deposited height was increased, the residual stress also increased; this internal residual stress combined with the external tensile load lead to a very low tensile strength of 447.79 ± 24.32 MPa of the ER80S-G/MF6-55GP/ER80S-G sandwich structure. The microstructures, constituent phases, and hardness distributions differ greatly among the layers due to their different thermal histories. The wear weight loss varies as the load condition changes for both the MF6-55G and Cr12MoV steels. Compared to Cr12MoV, MF6-55GP weld metal exhibits better wear resistance at higher loads in dry sliding wear tests.

Electron-Beam Welding of Large Thickness Steels of Oil Producing Platform Components

The paper treats problems of reducing the cost of welding and improving the quality and productivity of welding parts of cold-resistant steel of great thickness during the construction of oil platforms. The design of tooling structure and devices for electron-beam welding have been developed such as a welding wire feeder, a video observation system, and software for controlling the workpiece movement and the electron beam gun travel.

Microstructure and performances of dissimilar joints between 12Cr2Mo1R steel and 06Cr18Ni11Ti austenitic stainless steel joined by AA-TIG welding

Abstract 12Cr2Mo1R heat-resistant steel and 06Cr18Ni11Ti austenitic stainless steel are joined by Arc assisted activating TIG welding (AA-TIG) after using ERNiCr-3 and ER309 L filler metals pre-edge surfacing on the side of 12Cr2Mo1R. Scanning electron microscope (SEM) and optical microscope (OM) are used to study the microstructure of the joints. Microhardness, tensile strength and impact toughness are adopted to characterize the mechanical performances of the joints. Using CHI600D electrochemical workstation, and the potentiodynamic polarization and electrochemical impedance are employed to evaluate the corrosion resistance of the weld joints. The results show that the weld joints are formed well after pre-edge surfacing welding on the side of 12Cr2Mo1R base material. The microstructure of the weld by ERNiCr-3 and ER309 L welding wires pre-edge surfacing transition layer are single-phase austenite, austenite, and ferrite, respectively. The weld joint has excellent mechanical performances and corrosion resistance with the ER309 L welding wire pre-edge surfacing transition layer in the welding state.

Microstructural and mechanical properties of wire-arc additively manufactured Al–Zn–Mg aluminum alloy: The comparison of as-deposited and heat-treated samples

In this study, a thin-wall sample is built with a homemade Al-6.2Zn-2.2 Mg aluminum alloy welding wire using a gas welding arc as a heat source, then the deposit is subjected to the T6 heat treatment (HT). There are many second phases appeared in the as-deposited sample. Chemical analysis revealed an uneven distribution of Zn and Mg. The T6 HT processing reduced the amount and size of the second phase in the deposit, and Zn and Mg atoms are dissolved in the Al matrix, improving the elemental distribution in the sample. After T6 HT, properties of the deposits significantly changed: the average tensile strength (UTS) increased from 299 - 324 MPa to 389–402 MPa, the elongation decreased from 8.98%-9.66% to 4.18%–5.57%, and the microhardness is increased from 113 HV to 150 HV.

Investigation of microstructure and mechanical properties of AISI2205/DIN-P355GH steel joint by submerged arc welding

• In this study, AISI 2205 duplex stainless steel materials and P355GH pressure vessel steels are joined by using the same additional metal and powder, with the same parameters and submerged arc welding method. • Welded with SAW method, these materials were tested by eye, magnetic particle and radiographic examination methods to detect surface and sub-surface defects. No pores, voids or cracks were found in the materials after the magnetic particle test and radiographic test. In addition, solid spot and fixation of the welded samples worked, and welded samples showed no unacceptable angular distortion and high-low defect error. • Tensile, bending, impact notch and hardness tests were applied to determine the mechanical properties of welded samples. When the tensile test results are examined, it is seen that although the highest tensile strength of the main materials is in AISI2205 material, % elongation values are very close to each other. • Successful results have been achieved from all SAW of duplex stainless steel and pressure vessel steels. This result shows that additional metal, welding flux and welding parameters are suitable for joining duplex stainless steel and pressure vessel steels. In this study, duplex stainless (AISI2205) steel and pressure vessel (P355GH) steel have been joined by submerged arc welding method (SAW). Three different joining operations (AISI2205-AISI2205), (P355GH-P355GH) and (AISI2205-P355GH) were performed respectively. ELOX UP 309 L submerged arc welding wire and Eliflux Bss-A submerged arc welding powder were used for joining materials. Welded materials have been tested with eye, magnetic particle and radiographic examination methods were used to detect surface and subsurface defects. Tensile, bending, Charpy impact notch and hardness tests were then performed to determine the mechanical properties of welded samples. Additionally, microstructure investigations were made to determine the structural changes in the welding zone. Various NDE technqiues were adopted to investigate the quality of the welds. As a result of tensile tests, the rupture was made of welding metal in AISI2205-AISI2205 joints and P355GH in other joints was made of base material. No visible errors were observed in the welding area after bending test. When the V-notch impact energies of the materials were compared, the highest toughness value was measured in the ITAB of AISI2205 material and the lowest toughness value was measured in the P355GH weld metal. In hardness measurements, the highest hardness value was obtained in the HAZ of the AISI2205 material, whereas the lowest hardness was measured in the P355GH base material. Microstructure studies indicated that the weld metal comprised a dendritic structure, and the grains were observed to become coarse in the region adjacent to the melting boundary on the main material side.

Impact Toughness Characteristics of SM570-TMC Steel Joint Using Welding Wire Containing 0.4% Nickel at Different Level of Heat Input

The study was conducted to evaluate the impact toughness of flux-cored arc welded of SM570-TMC steel joint under different heat inputs, 0.9 kJ/mm (low heat input) and 1.6 kJ/mm (high heat input). Welding wire containing 0.4%Ni was selected on this experiment. Multi-pass welds were performed on SM570-TMC steel plate of 16 mm in thickness with a single V-groove butt joint on flat position (1G). The evaluation consists of observations on microstructure using an optical microscope and SEM-EDS, and mechanical properties including tensile, microhardness Vickers and Charpy V-notch (CVN) impact test at temperatures of 25, 0 and-20 °C. Results showed that the impact toughness of the base metal (BM) was higher than the weld metal (WM) at all test temperatures. Hardness and impact toughness of WM at low heat input was observed higher than when applied a high heat input. The welded samples at low and high heat inputs had high of tensile strength, and the fracture seemly occurs on the BM. Microstructure observation showed that at a high heat input, larger grains and microsegregation were observed. It might affect on decreasing their impact property.

Microstructures and mechanical properties of Al–Zn–Mg aluminium alloy samples produced by wire + arc additive manufacturing

To study the forming rule, microstructures and mechanical properties of Al–Zn–Mg alloy samples produced by wire+arc additive manufacturing (WAAM), a metal inert gas (MIG) arc was used as the heat source and 1.2-mm-diameter Al–6.2Zn–2.2Mg welding wires were used as the raw materials during single-pass, single-layer deposition and single-pass, multilayer deposition. In the single-pass, single-layer deposition, as the heat input increased, the number of ripples on the weld bead decreased, thereby making the surface smoother. Furthermore, under different parameters, there were always pores in the cross-section of the weld beads. In the as-deposited material, the elements were unevenly distributed due to the layer-by-layer deposition. There were two types of pores in the as-deposited material: pores caused by the presence of hydrogen and those caused by the burning loss of zinc. The as-deposited material exhibited an average hardness of 112HV. The horizontal test samples exhibited an average tensile strength of 324MPa, a yield strength of 208MPa, and an elongation of 9.66%. The vertical test samples exhibited an average tensile strength, yield strength and elongation of 299MPa, 188MPa and 8.98%, respectively. Moreover, the samples exhibited mixed ductile–brittle fractures.

Study on corrosion mechanism of high-nitrogen steel laser-arc hybrid welded joints

In this paper, the electrochemical microcorrosion behavior of High-nitrogen steel hybrid weld joints with different wires addition were investigated. Polarization curves measurement was conducted to evaluate the corrosion feature in 3.5% NaCl solution. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were used to analyze the specific corrosion behavior and pitting deepening mechanism induced by precipitated ferrite-dendrites. The experimental results showed that the addition of nitrogen-containing welding wire improved the corrosion resistance of whole weld joint. As a transitional region, the HAZ exhibited relative weak pitting resistance and severe shedding behavior. The coherent dendrites and similar complex geometries led to the accumulation of continuous corrosion channels. The XPS spectra results indicated that the additional nitrogen in the welding wire optimized oxide composition of the surface passive film.

Influence of heat input on the intermetallic compound characteristics and fracture mechanisms of titanium-stainless steel MIG-TIG double-sided arc welding joints

The influence of the heat input on the intermetallic compound (IMC) characteristics and the fracture mechanisms of titanium-stainless steel MIG-TIG double-sided arc welding (DSAW) joints using Cu–Si welding wire were studied. The results show that the MIG-TIG DSAW method can effectively control the microstructural characteristics by the heat input regulation. The Ti side interfaces were composed of IMC layers, mainly of Ti–Cu phases, and the thickness of the layers increased with increasing heat input. At the low heat input, the joints fractured at the 304SS side interface, which was embrittled by the straight IMC layer with the brittle TiFeSi and λ, Ti(Fe1-xSix)2 (0-x-0.375) phases. With increasing heat input, the melting of the 304SS reduced the interface brittleness by dispersing the brittle λ phase by softer Fe (s,s) and Cu (s,s) phases. At the high heat input, with the melted zone separated from the base metal, the remain-curved 304SS side interface improved the tensile resistance by increasing the load-bearing area. The fracture occurred at the Ti side interface, which embrittled by the thick IMC layers with a thickness greater than 130 μm. With the increase of the heat input, the joints showed an increase in tensile strength at the 304SS side interface but a decrease at the Ti side interface. The optimal tensile strength of 320 MPa was thus obtained in the joint under intermediate heat input, with a fracture position mixed with the Ti side interface and 304SS side interface.

Influence of arc energy and filler metal composition on the microstructure in wire arc additive manufacturing of duplex stainless steels

The influence of arc energy and filler metal composition on the microstructure of additively welded thin-walled structures of duplex stainless steels was investigated using different commercially available standard and superduplex solid wire electrodes commonly used today. As welding process, the cold metal transfer (CMT) process was used. The arc energy and cooling rate were varied by adjusting the wire feed and welding speed. Optical emission spectroscopy (OES) and carrier gas melt extraction (CGME) were used to determine the chemical composition of the specimens. The ferrite content was determined both by magnetic induction and by image analysis as a function of the wall height. In addition, the microsections were examined for intermetallic phases and precipitations. Moreover, corrosion tests were carried out according to ASTM G 48, Method A. The results indicate that an increase in arc energy leads to longer t12/8 cooling times. Depending on the filler metal composition, this leads to ferrite contents that are partially outside the values required according to ISO 17781. Furthermore, precipitates of secondary austenite are often found, which is attributed to the multiple reheating by the subsequent layers.