Deposited Weld Metal Research Articles

A Primary Study on the Applicability of Gel-Type Filler Materials to Root Pass Welds of the Thick Plate

Welding generally uses filler material to create deposited weld metal. Filler materials play a significant role in welding by providing the material needed to fill and form the joint. Existing filler materials are limited in the workspace and welding position and need help responding flexibly to welds of complex shapes. This study conducted primary research to develop a gel-type filler material with adhesion and flexibility that can cope with limited workspace and location. We attempted to provide a new approach to welding by mixing metal powder and binder to create a gel-type filler material. Root pass welding of thick plates was performed using a laser heat source. The bead appearance and cross-section of the weld zone were observed according to the type and composition of the metal powder, the binder content, and the method of synthesizing the metal powder. The physical characteristics of the weld were analyzed through observation of the hardness and microstructure of the weld.

Dissimilar joining of AZ31B and Ti–6Al–4V sheets in lap joint using cold metal transfer welding

Ti–6Al–4V and AZ31B alloy sheets were joined in lap joint configuration using cold metal transfer welding with a synergic power source. The torch angle was kept approximately 45° away from the top plate. Wire feed speeds (WFSs) have been varied from 3.0 m/min to 7.0 m/min. Cold metal transfer welding results in good deposition of weld metal at higher WFSs but at the cost of poor bonding and defects. Joints of the best qualities were fabricated at a WFS of 3.0 m/min and a welding speed of 0.6 m/min. The torch angle assisted in the proper deposition of AZ31B weld metal with a good bond between weld metal and Ti–6Al–4V base metal. Microstructural analysis confirms the joint interface integrity by revealing the absence of defects. Also, there is a significant variation among the grain morphology of weld region, transition zone and base metal. The presence of several oxides (MgO4, Al2O3, etc.) and intermetallics (Mg17Al12, Mg7Zn3, AlMg4Zn11, etc.) is indicated by metallurgical analyses. Tensile-shear tests revealed that the joints could sustain the maximum load of 1871 N. Fractography reveals the mixed mode of fracture containing majority brittle, and a ductile failure at a few locations. The unusual fracture at a few locations indicates the presence of oxides in these regions.

Research on the residual stress of stainless steel pipe after overlay repair

The weld overlays are widely used to repair metal butt welds or piping components by depositing weld metal on the outside surface of the welds and piping components. This paper presents the detailed residual stress distribution of girth weld in stainless steel pipe after butt welding and weld overlay repair by using finite element analysis. Two dimensional (2D) cross-section models, axisymmetric assumptions for piping girth welds are used to simulate the welding process in order to predict the residual stress distribution in the weld and base material. A project has been implemented to validate the analytical models used to perform welding residual stress analysis against measured residual stresses data in literature. It is found that the simulation results of butt welding are consistent with the experimental results in literature, which means that the analysis model and its results are accurate and reliable. A series of simulations are conducted to investigate the changing rules of influencing factors of overlay repair for stainless steel pipe. The results show that appropriate interpass temperature and heat input, increasing the thickness of overlay can effectively increase the range of compressive stress in pipe, so as to prevent and limit the generation and propagation of cracks. This research may provide an important support for the formulation of weld overlay repair standards in service.

Technological Features of Selection of Parameter Values of Arc Welding Mode in Shielding Gas Mixture Ar + CO<sub>2</sub>

Gas-shielded arc welding today occupies a leading position among the methods for producing permanent joints in industrial conditions. The emergence of new materials with complex alloying and hardening systems makes carbon dioxide, traditionally used as a protective medium, inefficient for use. One of the effective ways to solve these problems is to change the composition of the protective gas atmosphere, which allows you to significantly change the physical and metallurgical processes of melting the electrode wire and the forming the weld. At the same time, the transition to the use of protective gas mixtures based on argon is usually carried out without understanding the essence of the technology and possible problems associated with the specifics of penetration of the base metal, which can cause a number of serious problems. The present paper describes important regularities between technological characteristics of arc welding in a shielding gas mixture Ar + CO2 and welding mode parameters under conditions of deviation of their values from the most effective ones in order to ensure the stability of the processes of electrode metal transfer and the formation of the deposited weld metal bead. On the basis of experimental data, the most probable causes of the appearance of a dangerous and difficult-to-detect defect in the formation of a welded seam in the form of non-fusion between individual beads of the deposited metal and along the fusion line with the base metal of the welded parts have been established. The defect is common and can cause unpredictable failure of the welded joint without visible plastic deformation. Empirical dependences for determining values of the main parameters of the welding mode are proposed as well. Important regularities have been established that make it possible to increase the efficiency of arc welding technology in the environment of protective gas mixtures in the conditions of domestic production.

Investigating microstructural evolution and wear resistance of AISI 316L stainless steel cladding deposited over mild steel using constant current GMAW and pulsed current GMAW processes

Abstract The main objective of this study is to investigate the microstructure and wear resistance of AISI 316L austenitic stainless steel (ASS) cladding deposited over mild steel (MS) of grade IS 2062 using constant current (CC-GMAW) and pulsed current gas metal arc welding (PC-GMAW) processes. The PC-GMAW process was employed to overcome the problems of wider heat affected zone (HAZ), coarse grained deposited weld metal microstructure, lower penetration depth, higher dilution and reinforcement height encountered in CC-GMAW used for cladding of AISI 316L steel over mild steel. The microstructural features of cladded region were analyzed using optical microscopy (OM). The wear rate of cladded specimens was studied using pin-on-disc method and the morphology of wear surfaces was studied using scanning electron microscopy (SEM). The microhardness distribution of cladded region was analyzed and correlated to the wear performance of cladded specimens. The results showed that PC-GMAW cladding exhibit greater hardness and wear resistance compared to CC-GMAW cladding. It is correlated to the grain refinement offered by current pulsing in weld region of PC-GMAW cladding. The PC-GMAW cladding showed 5.22% increases in weld metal deposition compared to CC-GMAW cladding. The, PC-GMAW cladding showed 23.72% reduction in dilution of weld compared to CC-GMAW cladding. The PC-GMAW cladding disclosed 15.83 improvement in weld overlay hardness compared to CC-GAMW cladding. The PC-GMAW showed 20.18% average reduction in wear rate compared to CC-GMAW cladding.

Mechanical properties of aluminum to steel dissimilar spot joints produced by cold metal transfer weld-brazing

Spot joints between aluminum and steel sheets were produced by cold metal transfer arc welding using an AlSi3Mn alloy low melting point filler wire. The current study found that by using optimal welding conditions, the thickness of the joint interface was significantly reduced compared to previous studies. The interface thickness increased from a few nanometers at the center of weld to 1.7 micrometers (1.2 mm from center of weld) at periphery of weld. The reduction in joint thickness helped to achieve better joint properties. The tensile shear and fatigue properties of the spot joints were evaluated in conjunction with interrupted mechanical tests to determine the fracture mechanisms. This study investigates the fatigue properties and fracture mechanisms of cold metal transfer arc spot joints, which has not been done previously. The tensile shear fractures exhibit primarily interfacial fracture passing through an intermetallic compound layer at the joint interface. However, three different modes of fractures are observed during fatigue tests, including interfacial fracture, sheet fracture, and mixed-mode fracture. Interrupted fatigue tests reveal numerous crack initiation in pores/particles in the deposited weld metal and coagulation of those cracks leads to sheet fracture during the fatigue tests. Sheet fracture mode fractures are mainly observed during high cycle fatigue conditions.

Microstructural and wear properties of mild steel cladded with AISI 316L stainless steel using pulsed current gas metal arc welding process

The main objective of this study is to study the microstructure and wear resistance of mild steel (MS) of grade IS 2062 that has had an austenitic stainless steel (AISI 316L) coating applied utilizing the pulsed current gas metal arc welding (PC-GMAW) technique. The PC-GMAW method was used to overcome issues with the conventional gas metal arc welding (CC-GMAW) method used for cladding AISI 316L steel over mild steel, such as a larger heat affected zone (HAZ), coarse-grained deposited weld metal microstructure, less penetration depth and higher dilution and reinforcement height. Optical microscopy (OM) was used to examine the microstructural characteristics of the clad region. Using the pin-on-disc testing machine, the wear rate of cladded specimens was recorded, and scanning electron microscopy (SEM) was used to examine the morphology of wear surfaces. The microhardness distribution of the cladded region was examined, and the wear characteristics of the cladded specimens were correlated. According to the findings, PC-GMAW cladding is harder and more resistant to wear than a mild steel substrate. The PC-GMAW cladding exhibited higher weld metal deposition and lower dilution. Weld overlay hardness was 15.83% higher in the PC-GMAW cladding than in the mild steel substrate. The wear rate was decreased by an average of 20.18% as compared to the mild steel substrate with PC-GMAW cladding.

Evaluation of the corrosion behavior of different regions of the deposited weld metal from the Ni-modified E8018-G electrode

In this study, the corrosion behavior of different regions of the weld metal produced from the E8018-G electrode containing 7.0 wt% Ni in a corrosive solution has been investigated. X-ray diffraction (XRD) method has been used to compare the phase intensity in different welding regions. Electrochemical evaluations show that in the weld joint, by moving from the root of the weld metal to the upper layers of the center and cap, the corrosion resistance of the weld metal increases. In addition, the results demonstrates that the corrosion of the St-52 welded joint mainly occurs in the heat affected zone (HAZ). According to the microstructures observed from the spectra obtained by the field emission scanning electron microscopy (FE-SEM), the corrosion behavior of the weld metal has been evaluated. The examination of the local weld metal layers indicates that not only the corrosion resistance of the cap layer has improved compared to the central and root layers, but also the corrosion resistance has increased compared to the base metal. This improvement is attributed to the existence of a homogeneous acicular ferrite microstructure in the cap layer and higher nickel content.

Research of Drop Formation during Electric Arc Surfacing with the Use of Mechanical Control Impacts on the Electrode

Investigations of the influence of the parameters of mechanical effects on the temperature and mass of electrode metal droplets during electric arc surfacing with electrode materials of various chemical composition and type have been carried out. The main regularities of the process of droplet transfer during melting of a strip electrode with the introduction of control mechanical impacts have been established. The optimal range of the oscillation frequency of the strip electrode end is 40 ÷ 80 Hz, in which the average droplet diameter decreases to 1.3 ÷ 1.5 mm, and the mass to 0.08 ÷ 0.1 g. As a result of the research, it was found that, during electric arc surfacing with a strip electrode, changing the parameters of mechanical control impacts on the strip end allows not only to control the drop transfer frequency, but also to reduce the size and temperature of the electrode metal droplets, ensuring a decrease in heat input into the base metal and the formation of a favorable structure of the deposited weld metal.

The Path from Arc Welding to Additive Manufacturing of Multi-material Parts Using Directed Energy Deposition

Within this contribution, the transfer of knowledge from conventional fusion and deposition welding using electric arc processes to advanced directed energy deposition (DED) of multi-material structures in additive manufacturing are presented. Gas metal arc and plasma welding have been used for decades to produce either joints or metallic deposits with desired properties. Also creating certain shapes by depositing weld metal in a layer-wise manner has been known for approximately 100 years. With the rise of additive manufacturing, conventional arc welding processes have been extensively used to “print” 3‑dimensional parts. The possibility of additively manufacturing multi-material parts or transition parts is of particular interest as this has the potential to create load-efficient structures or even create new alloys within the AM process. Within this contribution, Wire Arc Additive Manufacturing (WAAM) and 3D Plasma Metal Deposition (3DPMD) for the manufacturing of multi-material and transition parts are discussed. The experience with various alloys from carbon steels, high-alloyed steels, and titanium- and nickel-based alloys are presented.

Suppression of Helium Induced Cracking in Laser Repair Welding of Highly Irradiated Stainless Steels

Welding repair of irradiated nuclear reactor materials such as austenitic stainless steels used for the reactor internals has been challenging due to irradiation generated helium in the material matrix over an extended period of time. In this study, improved laser welding techniques, including the novel Auxiliary Beam Stress Improved (ABSI) technique that proactively manages the stresses during laser repair welding is investigated to substantially reduce or avoid the occurrence of intergranular helium-induced cracking (HeIC). Laser weld cladding, with and without ABSI technique, was applied to deposit weld metal on irradiated stainless steel (Type 304 L) blocks with various helium concentrations up to approximately 20 atomic parts per million (appm). Welded samples were cross-sectioned and analyzed using optical and electron microscopes. It was found that, with the improved laser welding techniques, no macroscopic (millimeter-sized) cracks were observed in any of the samples. Microscopic (less than 50 μm) cracks were present in the heat affected zone. Statistical analysis on the sample with the highest helium concentration (~20 appm) reveals that the ABSI technique could effectively reduce the size and amounts of microscopic cracks.

Effect of Multi-pass SMAW Welding on the Surface Hardness and Microstructure of Carbon Steel AISI 1050

The objective of this work is to investigate the chemical composition, mechanical, and metallurgical properties of welded the carbon steel plates by electrode E7Cr utilize a shielded metal arc welding (SMAW) to weld three cases include one, two, and three passes. The material of the carbon steel plate was of type AISI 1050 with a thickness of 18mm, the diameter of the electrode was 3.2mm. A surface welding was used as a deposit on the surface of base metal with welding parameters of welding current = 90-140A, voltage = 21V. The welded workpiece was tested by a chemical composition analysis, Vickers hardness test, and microstructure test. The results refer that the chemical composition analysis of deposited weld metal achieved an increase in the alloying element of C, Cr, and Mn. The microstructure test of welding zone gives the microstructure different of the base metal, which it consists of a mixture of fine-grain Ferrite, dendrite, coarse dendrites, and Cr-carbide, especially in the third pass. The Vickers hardness test of the third layer had an estimate much higher than of the other layers.

Establishing empirical relationship between welding current and weld metal deposition rate for submerged arc welding process

Any increase in the productivity of the SAW process will immensely benefit the welding industry, as this process is widely used. Since the traditional single wire DCEP SAW system is extensively used even today, any enhancement using this system will benefit the industry in a big way, if this traditional SAW system is part of the improvisation process. This paper establishes a relationship between welding current and productivity (deposition rate), for the three common sizes of both solid wires and metal cored tubular wires at different current values over its full range, through bead-on-plate experimentation. At each preset current value, the weld bead was optimized for acceptable visual quality, by adjusting arc travel speed and voltage, then the wire feed rate-making optimized bead was noted. The weld metal deposition rate was calculated for establishing A vs WMDR empirical relationships. From the results, ten progressive strategies have been established which can improve welding productivity from 21 to 211% from baseline. The established relationships, strategies can be effectively used, to estimate/optimize the productivity based on the welding current values, for each wire type and diameter.

Microstructural characterization and mechanical properties of high-strength steel weld metals obtained by GMAW process with rotating electrode (GMAW-RE)

The GMAW process with rotating electrode (GMAW-RE) is a variation of the conventional GMAW process, where the electrode is submitted to a rotating movement, with pre-established rotation diameter and frequency. The method improves the lateral fusion along the sidewalls and contributes to the improvement of narrow gap welding, with significant gains in costs and productivity due to the reduced volume of the deposited weld metal. Although there are some studies about operational characteristics of the process, the literature involving mechanical properties of welded joints remains limited, requiring more experimental evidence to confirm the potential of this process for replacement of conventional GMAW process in industry. This work shows comparative analysis of mechanical and microstructural properties of high-strength steel weld metals obtained by the conventional GMAW and GMAW-RE processes. The weld metals obtained by multipass welding performed in steel plates with dimensions of 500 × 300 × 10 mm were submitted to Charpy-V notch, microhardness tests and metallographic examination from samples removed transversally to the weld bead. The residual stresses were analyzed using X-ray diffraction method at the top surface of the welded joints in the longitudinal and transverse directions of the weld bead. The results showed that the GMAW-RE welding procedure attained the approved standard according to the ASME IX Code, despite using materials with different mechanical strengths once the rupture of the test specimen after tension test has occurred on the base metal 7.4 mm far from fusion line. The joints did not show evidence of lack of fusion along the sidewalls, as verified by the bend tests and metallographic examination. In addition, the GMAW-RE process provided a weld metal with slightly superior mechanical properties compared to the GMAW process due to the more refined microstructure observed with higher amount of acicular ferrite, which favors the impact behavior. The association of higher productivity, reduced costs, lower residual stresses and adequate mechanical properties indicates that GMAW-RE process has a potential alternative for replacement of the GMAW in industrial applications.

High Martensitic Steel after Welding with Micro-Jet Cooling in Microstructural and Mechanical Investigations.

Modern means of transport will play a significant role in the smart city. In the automotive industry, high-strength steels such as Docol are employed more often. This kind of material is relatively not very well weldable. The main reason is related to the Heat Affect Zone, the region in which cracks occur. Another disadvantage is connected with differences in values of ultimate strength of parent and weld material. The differences can be diminished using the correct welding process, which employs nickel and molybdenum electrode wires at much lower sulfur content. The weld metal deposit contains mainly martensite and bainite with coarse ferrite, while the parent material contains mainly martensite and rather fine ferrite. New technology, micro-jet cooling after the joining process enables to obtain the microstructure of weld metal deposit at acceptable parameters. Welding with micro-jet cooling could be treated as a very promising welding Docol steels process with high industrial application. Results of non-destructive inspections on macro samples corresponded with further destructive test results (tensile strength, hardness, fatigue, metallographic structure analyses). This article aims to verify fatigue behavior of Docol 1200 M steel after welding supported by the cooling using the micro-jet technique. For the first time, micro-jet cooling was used to weld this kind of steel to check the mechanical properties of the joint, especially to determine the fatigue limit. This study is formulated as follows: investigating fatigue resistance of the Docol 1200 M weld manufactured at the cooling process with micro-jets. The joints were produced in the MAG (Metal Active Gas) technology modified by micro-jet cooling. The results collected in the fatigue test were processed in the form of the Wöhler’s S–N diagram following the fatigue limit of the weld examined. All data have indicated the possibility of obtaining a new method of welded joints with high fatigue limit minimum of 480 MPa. It could be important to achieve a tensile strength of 700 MPa while maintaining the best relative elongation at the level of the base material.

MAG Welding Process with Micro-Jet Cooling as the Effective Method for Manufacturing Joints for S700MC Steel

Advanced high-strength steel (AHSS) steels are relatively not very well weldable because of the dominant martensitic structure with coarse ferrite and bainite. The utmost difficulty in welding these steels is their tendency to crack both in the heat affected zone (HAZ) and in weld. The significant disadvantage is that the strength of the welded joint is much lower in comparison to base material. Adopting the new technology regarding micro-jet cooling (MJC) after welding with micro-jet cooling could be the way to steer the microstructure of weld metal deposit. Welding with micro-jet cooling might be treated as a very promising welding S700MC steel process. Tensile and fatigue tests were mainly carried out as the main destructive experiments for examining the weld. Also bending probes, metallographic structure analysis, and some non-destructive measurements were performed. The welds were created using innovative technology by MAG welding with micro-jet cooling. The paper aims to verify the fatigue and tensile properties of the thin-walled S700MC steel structure after welding with various parameters of micro-cooling. For the first time, micro-jet cooling was used to weld S700MC steel in order to check the proper mechanical properties of the joint. The main results are processed in the form of the Wöhler’s S–N curves (alternating stress versus number cycles to failure).

Comparison of Properties of Hardfaced Layers Made by a Metal-Core-Covered Tubular Electrode with a Special Chemical Composition.

In this article, the results of research on the metal-mineral-type abrasive wear of a wear-resistant plate made by a tubular electrode with a metallic core and an innovative chemical composition using the manual metal arc hardfacing process were presented. The properties of the new layer were compared to the results of eleven wear plates manufactured by global suppliers, including flux-cored arc welding gas-shielded (FCAW-GS, Deposition Process Reference Number: 138), flux-cored arc welding self-shielded (FCAW-SS, Deposition Process Reference Number: 114), automated hardfacing, and manual metal arc welding (MMAW, Deposition Process Reference Number: 111) hardfacing T Fe15 and T Fe16 alloys, according to EN 14700:2014. Characterization of the hardfaced layers was achieved by using hardness tests, optical microscopy, confocal microscopy, scanning electron microscopy, and EDS (Energy Dispersive Spectroscopy) and X-ray diffraction analyses. Based on wear resistance tests in laboratory conditions, in accordance with ASTM G65-00: Procedure A, and surface layer hardness tests, in accordance with PN-EN ISO 6508-1, the wear plates most suitable for use in metal-mineral conditions were chosen. The results demonstrated the high metal-mineral abrasive wear resistance of the deposit weld metal produced by the new covered tubular electrode. The tubular electrode demonstrated a high linear correlation between the surface wear resistance and the hardness of the metal matrix of the tested abrasive wear plates. In addition to hardness, size, shape, the dispersion of strengthening phases, and the base metal content, depending on hardfacing technology and technological parameters, impact wear resistance is represented by volumetric loss caused by effect-free or constrained dry abrasive medium contact. The presented results can be used in machine part material selection and wear planning for applications in inspection, conservation, and regeneration interval determination. The obtained results will be applied in a real-time wear rate prediction system based on the measurement of the working parameters.

Numerical investigation on stress distribution and evolution in 9Cr/2.25Cr dissimilar welded rotor undergoing welding and heat treatment

Numerical investigation has been employed to analysis stress distribution in 9Cr/2.25Cr dissimilar welded rotor undergoing welding and heat treatment in order to help optimize structural design. The simulated residual stress on inner and outer cylindrical surface has been validated with experimental data. Distribution and evolution of welding residual stress along weld center line through thickness has also been investigated. It is found that expansion due to martensitic phase transformation in cap weld and shrinkage in nominal HAZ determines the distribution of residual stress on outer cylindrical surface. Meanwhile, expansion caused by martensitic phase transformation and bending effect in annular structure is responsible for the evolution and distribution of through-wall residual stress. Distribution and peak value of through-wall welding residual stress remains after the weld height reaches a certain value (it is about 30% thickness from the inner cylindrical surface in this work), which provides a possibility to predict stress distribution with less time. Meanwhile, post weld heat treatment (PWHT) can release residual stress effectively. Hence, more attention has been paid to as-welded residual stress. Compared with 2.25Cr weld filler, 9Cr weld filler induces greater compressive hoop stress in the newly deposited weld metal and decreases the peak value of tensile hoop stress under it because of greater martensitic phase transformation expansion in cooling process and smaller yield stress at low temperatures.

Arc-welding based additive manufacturing for body reinforcement in automotive engineering

Arc-welding based additive manufacturing is a cost-efficient, productive technology which has been shown to be capable of producing high-integrity components. It is suggested that in automotive engineering, this manufacturing process can be used to reinforce body components by generating stiffening elements. Benefits of this method could be more flexural rigidity with comparatively lower material volume. In the current study, wire arc additive manufacturing (WAAM) with an advanced short arc welding process with low heat input was chosen. The first objective of the work was to check possibility of generating a gusset plate on zinc-coated car body parts by additive manufacturing, for reinforcing of formed thin steel sheets. The second aim was to increase flexural rigidity of the sheets by depositing weld metal as a grid. Bending tests of the sheets indicated an increased flexural rigidity compared with the parent material. This production method and the results of this study are related to automotive engineering but could be employed for other applications. The aim is to demonstrate how these goals could be approached, what difficulties and limitations exist, and where further research work could be initiated.

ESTABLISHING RELATIONSHIP BETWEEN WELDING CURRENT AND WELD METAL DEPOSITION RATE FOR SOLID WIRE IN SUBMERGED ARC WELDING PROCESS

Submerged Arc Welding (SAW) process is used to weld large, heavy metal deposition jobs with critical requirements, and this metal joining process alone is used to weld approximately 10% of the deposited weld metal worldwide. Any augmentation in productivity of SAW process, will immensely benefit the welding industry, as this process is widely used on variety of common metals and alloys. This paper focusses on establishing relationship between welding current and productivity (in terms of weld metal deposition rate as an index), for a given filler wire diameter. Productivity rates of most common solid filler wire sizes were studied, at different preset current values, covering full current range through bead-on-plate experiments. At each preset current value, the bead was first optimized for acceptable visual quality, by varying arc travel speed and voltage, then wire feed rate (of acceptable beads) was noted. The current density, heat input and corresponding weld metal deposition rate were calculated for establishing relationships. The established relationships can be effectively used, to estimate productivity from the preset current values, for a given solid wire diameter.