Weld Metal Research Articles

The Influence of Different Hot-Dip Zinc Coating Types on the Gas Metal Arc Welding of Galvanized Steel Sheets

Abstract The work was focused on evaluating the influence of the structure of the protective Zn coating on steel sheets on arc welding. Two types of galvanized steel sheets were used in the experiments, HX340LAD + ZF (GA type) and HX300LAD + Z (GI type), with a thickness of 2 mm. First, the analysis of the structure of the Zn protective layer was carried out on the selected materials. After that, test welds were made using the gas metal arc (GMA) welding in the short-circuit metal transfer. The influence of the type of protective Zn coating on the occurrence of defects, the geometry of the weld, and the stability of the welding process was evaluated. From the achieved results, it can be concluded that the protective Zn layer on the HX340LAD + ZF sheet was formed by intermetallic phases FexZny-Fe concentration ranged from 19.0 wt.% (at the steel plate coating interface) up to 9.5 wt.% (on the coating surface). An Fe-Al inhibitor layer was observed at the steel sheet-coating interface of the HX300LAD + Z material, while the Fe content in the Zn coating decreased from 8.2 to 0.8 wt.% towards the surface. Better weld evaluation results were achieved on samples made on HX340LAD + ZF galvanized sheet. The welds were without porosity, and the stability parameter (electric arc stability criterion) was almost two times smaller than the stability parameter in the evaluation of the HX300LAD + Z sheet metal welding process.

Facet-Dependent Cold Welding of Au Nanorods Revealed by Liquid Cell Transmission Electron Microscopy.

Cold welding of metals at the nanoscale has been demonstrated to play a significant role in bottom-up manufacturing and self-healing processes of nanostructures and nanodevices. However, the welding mechanism at the nanoscale is not well understood. In this study, a comprehensive demonstration of the cold welding process of gold nanorods with different modes is presented through in situ liquid cell transmission electron microscopy. The experimental results and molecular dynamics simulations reveal that the nanorods are welded through the facet-dependent atomic surface diffusion and rearrangement along {100} facets. The density functional theory calculations indicate that the preferred coalescence of two {100} surfaces is thermodynamically favorable. Unlike the prevalent "oriented attachment" in the nanoparticle coalescence, the misalignment of nanorod orientations and local stresses can induce grain boundaries and stacking faults in the welded interface.

Investigation on flux design & their effect on the mechanical properties of the SAW of Duplex Stainless Steel-2205

Abstract The SAW fluxes for Duplex Stainless Steel (DSS)-2205 are not easily available. Generally, the available flux configuration is suitable for different grades of stainless steel but not suitable for the DSS. The current research aims to formulate the flux for DSS-2205 by varying the different flux ingredients and to investigate the impact of linear flux ingredients and their binary mixture effect on the mechanical characteristics of the butt joining of DSS-2205. The technique of extreme vertices design suggested by McLean and Anderson is employed to develop twenty-one fluxes. The effect of twenty-one flux ingredients was analyzed on the fabricated weldment’s characteristics such as ultimate tensile strength (UTS), percentage elongation, impact strength, and microhardness. In this research, a mathematical model has been developed for UTS, percentage elongation, impact strength and microhardness of weld specimens in terms of the flux ingredients. It is found from the experiments that the tensile strength and percentage elongation of weldments is increased by the flux ingredients such as silica (SiO2) and magnesium-oxide (MgO), while the alumina (Al2O3) and calcium fluoride (CaF2) has decreasing effect on UTS. Impact strength is found to be decreased by the linear effect of Al2O3. Excluding CaF2, all the linear flux ingredients have an increasing effect on the microhardness of the weld metal. Increased binary effect of Al2O3.CaF2, Al2O3.MgO, and MgO.CaF2 flux ingredients are found on the UTS, percentage elongation, impact strength and microhardness of the weldment. For the adequacy of the developed regression model, analysis of variance (F-statistics) is used for all the regression equations.

Microstructure and Corrosion Behaviors of Gas Tungsten Arc Welds for Borated Stainless Steel Using Various Filler Metals

In this study, the microstructure and corrosion behavior of gas tungsten arc (GTA) welds of borated stainless steel (BSS) with a boron content of 1.62 wt.% were investigated using various filler metals. The filler metals used in this study were 308L, 309L, and 310 without the B component. A small amount of the B component was observed in the weld metal (WM) of all specimens, even though none of the filler wires contained boron. This result was caused by the dilution of the B component from the BM into the WM by the welding heat. The segregation of boron in the WM resulted in Cr-depleted areas, which negatively affected the corrosion resistance of the welded specimens. The corrosion resistance of 308L WM with the highest fraction of B components was the most deteriorated, whereas 309L WM with the lowest boron content exhibited the best corrosion resistance. Using a filler metal without the B component is expected to effectively improve the weldability and corrosion resistance of BSS; however, it can also reduce the neutron absorption capacity. Therefore, for BSS to be used as a spent nuclear fuel storage container material, the boron content of the filler metal must be carefully considered. This study provides a foundation for research aimed at improving the development and applicability of filler metals in borated stainless steel and makes it competitive for application in fourth-generation nuclear power systems.

Determination of the Effective Microstructural Unit in Relation to the Weld Metals Brittle Fracture Resistance

Metallographic studies of the high-strength, low-alloy steels weld metal structure show that the cracks in the structure can pass through several grains, or stop at the grain boundary or in the middle of the grain. Resistance to weld metal brittle fracture is usually associated with the grain size in its structure. Recently, works have appeared in the scientific and technical literature, in which instead of grain sizes, that is, the solid solution region delineated by the phase boundary, it is proposed to determine the influence of the solid solution region with a close orientation of ferrite formations. Purpose of the article: To clarify the grain size definition for the welds metal structure. Recently, works have appeared in the scientific and technical literature, in which instead of grain sizes, that is, the solid solution region delineated by the phase boundary, it is proposed to determine the influence of the solid solution region with a close orientation of ferrite formations. Key Idea: For weld metal, the structural grain size is determined by the disorientation index at the grain boundary. The article presents a critical analysis of the authors results concerning the point of view on the validity of such an approach to assessing the influence of microstructure on the metal of welds mechanical properties. Conclusion: When analyzing the weld metal structure influence on the mechanical properties, the grain size must be determined using the disorientation parameter at the grain boundary.

Influence of the cooling time t8/5 on weld metals

Influence of the cooling time t8/5 on weld metals

Effect of Hardness Distribution on Strength of Narrow-Gap Hot-Wire Laser-Welded Joint for High-Tensile Strength Steel.

Application of high-heat input welding on high-tensile strength steels causes deterioration of mechanical properties of the welded joint, due to softening and grain coarsening in the heat-affected zone (HAZ). In this study, low-heat input narrow-gap hot-wire laser welding was applied to 12 mm thick 780 MPa-class high-tensile strength steel plate. Conditions were optimized based on microstructural observations of joints produced at various welding speeds. Heat input was estimated from measured grain size. Evaluation of properties of joints welded at 0.5 m/min revealed sound toughness, tensile strength, and elongation. The effect of undermatched weld metal width on joint strength was analyzed using a finite element method. When the width of undermatched weld metal was 2.5 mm, the joint strength was 99% of the base metal strength; when it was 7.5 mm, the strength dropped to 95%. The effect of HAZ softening width on joint strength with even-matched weld metals was similarly analyzed, showing that even when the HAZ softening width was 2.0 mm, the joint strength was 98% of the base metal strength. The results of this study suggest that narrow-gap hot-wire laser welding can efficiently reduce heat input and the HAZ softening zone, thereby achieving both high strength and high toughness.

A new methodology for investigating the weld joint microstructure and micro-hardness of the austenitic stainless steel clad plate made by SMAW/GTAW multi-pass welding process: part III – clad layer case study

In this study, the influence of repeated thermal cycling during multi-pass welding on the microstructural transformations and mechanical properties of austenitic stainless clad-steel plates (ASCSPs) was investigated, with a particular focus on the clad layer. A novel methodology was employed, involving the complete filling of the groove length and gradually shortening subsequent passes. Microstructural characterization of various zones within the welded joint was conducted using optical microscopy. The results demonstrated that repeated thermal cycles during multi-pass welding caused significant microstructural changes in the weld metal clad layer (WM-CL), including the transformation from columnar to equiaxed grains and the evolution of δ-ferrite morphology from dendritic to skeletal. Additionally, the ferrite number decreased from 8.5 ± 2 in the sixth pass to 2 ± 0.5 in the ninth pass, correlating with increased heat input (HI) from 15.5 kJ/cm to 25.8 kJ/cm and repeated thermal cycling. Furthermore, the heat-affected zone (HAZ) exhibited coarse-grained polygonal austenite near the fusion line, with recrystallization attributed to the high thermal input. Micro-hardness measurements showed a reduction from 320 HV in the sixth pass to 195 HV in the ninth pass, linked to alloying element diffusion and ferrite content reduction. The findings highlight the importance of controlling thermal cycles and HI during multi-pass welding to optimize the microstructural stability and mechanical properties of ASCSP welded joints. These results provide valuable insights for improving the performance of ASCSP in industrial applications.

Effect of Filler Metal Chemistry on Preferential Weld Corrosion in Hydrocarbon and Produced Water Service Using the Galvanostatic Method

The effect of Ni content in weld consumables on the preferential weld corrosion (PWC) of welded pipeline steel for hydrocarbon and produced water service has been investigated using the galvanostatic method as a preliminary assessment tool. The method involves the application of a modest anodic current to the weldment over a short period, in this case, 62 h. The distribution of material loss and the extent of PWC is then characterized by 3D profiling. Testing was conducted for 0% Ni, 1% Ni, and 2% Ni weld fillers in 50 g/L NaCl at 60°C with 1 bar CO2. For these sweet environments, the results demonstrate an increased resistance to corrosion of the weld metal and heat-affected zone (HAZ) for the Ni-weld filler, compared to the weld metal free of Ni and the parent steel. However, for all weldments, the fusion zone and HAZ/parent steel interface were more prone to attack than the parent steel, albeit the addition of Ni reduced the extent of corrosion at the fusion zone.

Microstructure of Joints Made of Duplex Steel LDX 2101 Using Concentrated Beams and Various Welding Rates

The article presents tests concerned with the welding of duplex steel LDX 2101 using a laser beam, an electron beam and various welding rates. Flat butt joints were made using the laser beam and welding rates of 1 m/min and 2 m/min as well as the electron beam and welding rates of 0.2 m/min and 2 m/min. Microscopic metallographic examinations involved the use of light microscopy. The microstructure of individual areas of the test joints was revealed using colour electrolytic etching. Structural components in individual areas of the joints were identified using NIS Elements-AR software tools (Nikon). The same software was used for measuring the width of the joints and the height of excess weld metal. Test results were used to formulate related conclusions.

Swing and Electrode Diameter Effects on Toughness and Hardness of Stainless Steel 304 MIG Welding Results

Welding is one of the commonly used methods for joining metals. One of the welding techniques frequently employed is MIG welding (Metal Inert Gas welding). This type of welding is typically used for joining stainless steel. Consequently, many factors need to be analyzed to achieve optimal welding results. The objective of this research is to investigate the influence of swing variation and electrode diameter on hardness, toughness, and macrostructure from the welded stainless steel 304 using MIG welding. The research results showed the highest toughness test results with a 2.0 mm electrode diameter and a zig-zag swing of 0.459 J/mm2, while the lowest toughness test results were obtained with a 2.6 mm electrode diameter and a spiral swing of 0.201 J/mm2. The highest hardness test results were observed with a 2.6 mm electrode diameter and a zig-zag swing in the Heat Affected Zone (HAZ) at 292.0 kg/mm2, whereas the lowest hardness test results were obtained with a 2.0 mm electrode diameter and a zig-zag swing in the welded metal at 203.6 kg/mm2. The widest HAZ occurred with the spiral swing variation and a 1.5 mm electrode diameter, resulting in a HAZ width of 1.92 mm, while the narrowest HAZ of 1.25 mm occurred with the spiral swing variation and a 2.0 mm electrode. Thus, it can be concluded that the electrode diameter variation affects the results of toughness, hardness, and macrostructure tests.

Design strategies for enhancing strength and toughness in ultrasonic welding of dissimilar metals: A review

Design strategies for enhancing strength and toughness in ultrasonic welding of dissimilar metals: A review

Laser surface remelting enhances microstructure uniformity and improves corrosion resistance of low-alloy steel weld metals

Laser surface remelting enhances microstructure uniformity and improves corrosion resistance of low-alloy steel weld metals

Corrigendum to ‘Residual stress assessment for dissimilar metal welds in nuclear power plant’ [Int. J. Pres. Ves. Pip. Volume 206, December 2023, 105018

Corrigendum to ‘Residual stress assessment for dissimilar metal welds in nuclear power plant’ [Int. J. Pres. Ves. Pip. Volume 206, December 2023, 105018

Проблеми зварювання високомарганцевих сталей

The sensitivity of high-manganese steels to deformation and heat treatment leads to problems with their welding. They consist in the tendency to crack formation in the zone of thermal influence during rapid heating and cooling. They are also characterized by sensitivity to overheating, which is expressed in the possibility of the carbides precipitation and structure heterogenization. Tendency to cold-hardening due to welding stress can also cause micro- and macro-defects and reduce the quality and reliability of the welded joint. The work represents analysis of the modern global experience of high-manganese steels welding in various ways and with the use of various materials. The importance of maintaining the homogeneity of the chemical composition between the weld metal and the base material is shown in order to prevent the formation of martensite due to an austenite stability decrease. While welding dissimilar steels, the release of harmful carbides can occur, so such joints should be preheated with controlled cooling. Welding of high-manganese austenitic steels is not recommended to be performed with a consumable electrode made of stainless austenitic steel due to the formation of significant structural and phase heterogeneity, eutectics and cracks that can pass from the welding zone through heat affected zone to the base metal. As a result of the research analysis, it was established that the welding of high-manganese steels is best performed with electrodes with a chemical composition that is close to the materials being welded. Before welding, it is recommended to reduce the level of residual stress and cold hardening by heat treatment. Welding should be carried out under the conditions of minimizing the thermal load on the material, which is achieved by low-current and short-seam welding, as well as by preheating the metal. For welding thin parts from high-manganese steels, laser welding can be used. For larger thicknesses, welding with a fusible electrode in an environment of shielding gases (MIG\MAG) and argon arc welding with a non-fusible electrode (TIG) is applicable.

The effect of TIG welding technology parameters on the weld quality of copper material joints for heat pipe applications

Copper is a commonly used material for heat pipe fabrication using the welding process. However, welding copper to copper presents significant challenges due to its inherent material properties. Its exceptionally high thermal conductivity facilitates rapid heat dispersion, complicating the maintenance of a stable melting zone. Furthermore, copper is prone to oxidation, which generates brittle oxides that can adversely affect weld quality. This research paper examines the relationship between TIG welding parameters—specifically current, voltage, shielding gas flow rate, and filler rods—and the mechanical properties of the resulting heat pipe material. The study involves varying the welding current at levels of 120 A, 135 A, and 150 A, along with different types of filler rods. The results indicate that both the selection of welding current and the type of filler rod significantly influence the tensile strength of copper welded joints. Notably, the use of higher currents in ERCuSi-A welding tends to decrease hardness in the HeatAffected Zone (HAZ), while producing more complex variations in hardness within the Weld Metal (WM), dependent on the interplay between heat and the chemical composition of the filler rod. Additionally, nickel in the ERCuNi filler rod contributes to an increase in weld hardness.

Atomistic Simulation of Temperature-Dependent Interfacial Diffusion between Solid Nickel and Liquid Aluminum

The performance and durability of welded joints are directly influenced by interfacial diffusion between the metals involved, making it essential to investigate the effect of temperature on these processes. The present research examines temperature-dependent diffusion mechanisms at the interface between solid nickel and liquid aluminum using molecular dynamics simulations. Investigations were conducted at 1200, 1300, 1400, and 1500 K to explore the influence of temperature on atomic mobility and interfacial mixing. Radial distribution function analysis revealed a significant increase in the diffusion of nickel atoms into the aluminum phase with increasing temperature, indicating enhanced atomic interactions at the interface. The mean square displacement analysis supported these findings, showing that aluminum atoms were more mobile than nickel atoms at lower temperatures, while nickel atoms exhibited a faster diffusion rate with increasing temperature, surpassing aluminum in mobility. This trend is reflected in the diffusion coefficients, which exhibit a temperature-dependent increase in the diffusion rate of the nickel atoms. These results emphasize the role of temperature in controlling the diffusion dynamics at the solid–liquid interface. The insights gained from this study are critical for optimizing processes, such as dissimilar metal welding, where precise control over interfacial diffusion is essential for achieving the desired material properties and ensuring the structural integrity of nickel–aluminum joints in high-temperature applications.

Probing the synergistic effect Ni and Mo contents on microstructure–toughness relationship in super-high strength steel weld metals

This study aims to investigate the synergistic effect of Ni-Mo contents on microstructural evolution in super-high strength steel weld metals, and its following influence on toughness is also explored through crystallographic analysis. The results indicate that the microstructures of both weld metals are acicular ferrite, grain boundary ferrite, ferrite side-plate and bainitic ferrite. Compared with high-Ni–Mo weld metal, the decrease in Ni–Mo content increases the acicular ferrite fraction instead of bainitic ferrite. The crystallographic characteristics confirm that the adjacent parallel bainitic ferrite tend to be in the single Bain group in variant selection, while adjacent interlocking acicular ferrite belonged to multiple Bain groups. The multiple Bain groups contribute high-density large-angle grain boundaries, leading toughness improvement in low-Ni–Mo weld metal.

Selection of the Process of Arc Welding of Sealing Surfaces of Power Valves with a Consumable Electrode in the Shielding Gas

Introduction. One of the main requirements to the methods of weld overlay of sealing surfaces of power valve trim parts is to obtain a high-quality wear-resistant pad with minimal penetration and optimal process performance. Currently, arc, electroslag, plasma, beam, induction and other surfacing techniques have been developed and introduced into production. However, the influence of various arc welding processes with a consumable electrode in shielding gas on the geometric parameters of weld beads and metal hardness of sealing surfaces is understudied. The presented research is intended to fill this gap. The objective of its authors is to select such a process of arc welding of beads on parts of the power valve trim with a consumable electrode in shielding gases, which would provide the best workability of the deposited metal.Materials and Methods. Arc surfacing with a consumable electrode in a mixture of gases was performed on steel plates. The welding torch was moved in a straight line, without transverse oscillations, using the FRC-9 mechanism (Fronius). A microprocessor-controlled inverter-type digital current source TransPulsSynergic 3200 CMT (Fronius) was used as the power supply. The following welding processes were analyzed: MIG/MAG process with self-regulation (Standard mode), synergic process of MIG/MAG method (Synergic mode), short arc process with mechanical separation of electrode metal droplets (CMT-ColdMetalTransfer), and synergic pulse-arc process (PulseSynergic). The short-cut process of bead surfacing was evaluated by the stability of the values of the energy parameters of the bead surfacing mode in time at the same electrode wire feed rates, which were recorded by oscilloscopes, as well as by comparing the geometric characteristics of the deposited beads and the hardness of the deposited metal.Results. The analysis of experimental data of the geometrics of the weld beads and their complex dimensional characteristics made it possible to establish that the welding engineering requirements for the welded beads are most fully met by long-arc surfacing by the PulseSynergic pulse-arc process.Discussion and Conclusion. The study and the resulting data make a certain contribution to solving the problem of the influence of arc welding processes on the parameters of weld beads and on the hardness of the metal of sealing surfaces. A detailed analysis of the modes of arc surfacing of beads with a consumable electrode in shielding gases on the trim parts of power valves can be used in further research on this topic. The conclusions of the authors will not only provide considerable theoretical assistance to scientists, but will also make adjustments to the activities of practitioners.

Effect of Oscillating Amplitude on Microstructure and Mechanical Property of Laser Welding of Dissimilar Stainless Steel

The development of oscillating laser beam welding (OLBW) provides an opportunity to improve the weld formation of dissimilar stainless steels. In this paper, the influence of oscillating amplitude on the weld formation, microstructure, and mechanical properties of dissimilar 430/5Cr15MoV stainless steel was studied. The results showed that the weld morphology became smooth and uniform with an increase in the oscillating amplitude, and there was no obvious defect on the surface. The formation mechanism of weld overflow defects on the weld surface was discussed. The width of the weld metal increased with an increase in oscillation amplitude. The influence of beam oscillation on the microstructure of the weld center was significant, i.e., the proportion of equiaxed grains in the center of the welds increased as the oscillation amplitude increased. The maximum microhardness of the weld was obtained at an amplitude of 1.5 mm. Moreover, the tensile strength of the welds reached 477 MPa, which was comparable to the tensile strength of the 430 stainless steel base material. The fracture modes of all welds were typical ductile fractures, which suggests that the oscillation amplitude had a minor effect on the fracture mechanism of the welds. This study provided a new approach to welding dissimilar stainless steels and offers guidance for the selection of an optimum oscillation amplitude.