Gas Metal Research Articles

Effect of post-weld heat treatment on microstructure and mechanical properties of twinning-induced plasticity (TWIP) steel joints

The effect of post-weld heat treatment on microstructure and mechanical properties of twinning-induced plasticity (TWIP) steel joints obtained by melting electrode inert gas-shielded welding (MIG welding) was systematic studied. A total of two post-weld heat treatment processes are proposed, i.e., post-weld annealing treatment (PWAT) with temperature/time of 1100 ℃/1 h and subsequent furnace cooling and post-weld solution treatment (PWST) with temperature/time of 1100 ℃/1 h and subsequent water quenching, which were compared with the case of post-weld non-treatment (PWNT). Following annealing treatment at 1100°C, the joint tensile strength dropped by 6.6 % (from 845.46 MPa to 789.85 MPa), while its elongation at break increased by 40.87 % (from 29.80 % to 41.98 %). The significant increase in plasticity was due to the significant elimination of weld stresses in the joints after annealing. Moreover, the stresses in the weld metal of the PWST joints were instead significantly elevated and the carbides were solidified, which resulted in the lower strength. When post-weld heat treatment was applied, the impact toughness of the joints was lower than when untreated. This was primarily due to the greater percentage of the low-angle grain boundaries and the precipitation of MC-type carbides. Consequently, post-weld annealing treatment was an effective method to further enhance the strong plasticity of new twinning-induced plastic steel joints.

Analysis of Gas Metal Arc Welding Process Using Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise

Analysis of Gas Metal Arc Welding Process Using Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise

Microstructure and properties of metal inert gas welded joints in a novel Al–Mg–Zn–Er–Zr alloy

Metal inert gas (MIG) welding of a novel Al-5.82Mg-0.61Zn-0.14Er-0.11Zr alloy was performed using ER5E61 and ER5B71 filler wires. The effect of the two filler wires on microstructures and mechanical properties of MIG welded joints was investigated. The study shows that fully penetrated joints are obtained by MIG welding process filled with ER5E61 and ER5B71 wires. Compared with ER5B71, the weld metal (WM) with ER5E61 exhibits a coarse structure and high solid solution of Mg and Mn elements. After the tensile test, the WM with ER5E61 and ER5B71 wires is composed of elongated coarse grains with a higher proportion of low angle grain boundaries (LAGBs). In addition, the lattice rotation occurring within the grains, indicating that single grain has an unevenly plastic deformation after the tensile test. The average microhardness of the WM is 83.4 HV and 82.9 HV for ER5E61 and ER5B71 wire, which is the lowest microhardness in the MIG welded joint. The average ultimate tensile strength (UTS) and elongation index (EI) of the MIG joints are 327.7 MPa and 8.5% for ER5E61 wire, and 314.3 MPa and 8.2% for ER5B71 wire, suggesting the MIG welded joint with ER5E61 wire achieves a good combination of strength and ductility. Quantitative assessments of the effects of different strengthening mechanisms on the strength reveal that dislocation strengthening and solid solute strengthening are the main factors to obtain a higher strength of welded joints with ER5E61.

Evaluation of nano indentation behavior of TIG, MIG and diffusion bonded Inconel 718 and austenitic Stainless Steel 316L joint interface

The nanomechanical characteristics of Metal Inert Gas (MIG), Tungsten Inert Gas (TIG), and diffusion-bonded Inconel (IN718) and Austenitic Stainless Steel (SS 316L) were investigated. The nano hardness and elastic modulus of different weldments were evaluated using nanoindentation and compared. The results showed that intermetallic compounds (IMCs) and carbides were reduced with diffusion bonding. Moreover, maximum nano hardness and elastic modulus occurred in the welded zone (WZ) of TIG and MIG welded joints while at the bonding interface in diffusion bonding (DB). Lastly, the nano hardness of the bonding interface in diffusion-bonded was 11 % and 7 % lower compared to MIG and TIG welded joints.

Metallurgical and mechanical properties of marine grade AA5356 using wire arc additive manufacturing

In the current work, a Gas metal arc welding (GMAW)-based Wire Arc Additive Manufacturing (WAAM) procedure was used to build a wall construction of measuring Aluminium alloy (AA) AA5356 on an AA5083 base plate. The microstructure and mechanical properties of AA5356 were examined at two places along the wall structure’s horizontal deposition direction and in two deposition orientations (horizontal and vertical). Optical microscopy, SEM, EDAX, and fractographical examinations were used to analyse the microstructure. Tensile and microhardness tests were performed at two wall locations to evaluate mechanical parameters. A microstructure analysis reveals a mixture of columnar grain structure and coarser intermetallics in the remelting zone, with finer granular structure in the central region. The horizontal direction of AA5356 deposition exhibited a highest elongation and tensile strength of 4.4% and 249 MPa than the vertical direction. For the horizontal and vertical orientations, the average microhardness values were determined to be 80 HV and 72 HV, respectively. Fracture analysis of the tensile samples showed that the deposited metal had a ductile mode of failure with a predominance of dimples with tearing shape. This study provides valuable insights into constructing wall structures and analyzing their mechanical properties.

A Comprehensive Metallicity Analysis of J0332−3557: Establishing a z ∼ 4 Anchor for Direct Gas Metallicity and C/O Abundance Investigations

We provide one of the most comprehensive metallicity studies at z ∼ 4 by analyzing the UV/optical Hubble Space Telescope photometry and rest-frame Very Large Telescope (VLT)/FORS2 UV and VLT/XSHOOTER optical spectra of J0332−3557, a gravitationally lensed galaxy magnified by a factor of 20. With a 5σ detection of the auroral O iii] λ1666 line, we are able to derive a direct gas metallicity estimate for our target. We find Z gas =12+log(O/H)=8.26±0.06 , which is compatible with an increase of both the gas fraction and the outflow metal loading factor from z ∼ 0 to z ∼ 4. J0332−3557 is the most metal-rich individual galaxy at z ∼ 4 for which the C/O ratio has been measured. We derive a low log(C/O) = −1.02 ± 0.2, which suggests that J0332−3557 is in the early stages of interstellar medium carbon enrichment driven mostly by massive stars. The low C/O abundance also indicates that J0332−3557 is characterized by a low star formation efficiency, higher yields of oxygen, and longer burst duration. We find that EWC III]1906,9 is as low as ∼3 Å, and the main drivers of the low EWC III]1906,9 are the higher gas metallicity and the low C/O abundance. J0332−3557 is characterized by one diffuse and two more compact regions ∼1 kpc in size. We find that the carbon emission mostly originates in the compact knots. Our study on J0332−3557 serves as an anchor for studies investigating the evolution of metallicity and C/O abundance across different redshifts.

Galaxies with grains: unraveling dust evolution and extinction curves with hydrodynamical simulations

Dust in galaxies is an important tracer of galaxy properties and their evolution over time. The physical origin of the grain size distribution, the dust chemical composition, and, hence, the associated ultraviolet-to-optical extinctions in diverse galaxies remains elusive. To address this issue, we introduce a model for dust evolution in the RAMSES code for simulations of galaxies with a resolved multiphase interstellar medium. Dust is modelled as a fluid transported with the gas component, and is decomposed into two sizes, 5 nm and 0.1 μm, and two chemical compositions for carbonaceous and silicate grains. This dust model includes the growth of dust by accretion of elements from the gas phase and by the release of dust in stellar ejecta, the destruction by thermal sputtering, supernovae, and astration, and the exchange of dust mass between the two main populations of grain sizes by coagulation and shattering. Using a suite of isolated disc simulations with different masses and metallicities, the simulations can explore the role of these processes in shaping the key properties of dust in galaxies. The simulated Milky Way analogue reproduces the dust-to-metal mass ratio, depletion factors, size distribution and extinction curves of the Milky Way. Galaxies with lower metallicities reproduce the observed decrease in the dust-to-metal mass ratio with metallicity at around a few 0.1 Z⊙. This break in the dust-to-metal ratio corresponds to a galactic gas metallicity threshold that marks the transition from an ejecta-dominated to an accretion-dominated grain growth, and that is different for silicate and carbonaceous grains, with ≃0.1 Z⊙ and ≃0.5 Z⊙ respectively. This leads to more Magellanic Cloud-like extinction curves, i.e. with steeper slopes in the ultraviolet and a weaker bump feature at 2175 Å, in galaxies with lower masses and lower metallicities. Steeper slopes in these galaxies are caused by the combination of the higher efficiency of gas accretion by silicate relative to carbonaceous grains and by the low rates of coagulation that preserves the amount of small silicate grains. Weak bumps are due to the overall inefficient accretion growth of carbonaceous dust at low metallicity, whose growth is mostly supported by the release of large grains in SN ejecta. We also show that the formation of CO molecules is a key component to limit the ability of carbonaceous dust to grow, in particular in low-metallicity gas-rich galaxies.

DOCOL 1100M WELDING IN THE CONSTRUCTION OF ELECTRIC MEANS OF TRANSPORT

Advanced high-strength steels are important for the automotive sector. Metal active gas (MAG) is the most popular method for joining grades of steel. The goal of the paper is to analyze the mechanical properties of the MAG welding joint made of high-strength DOCOL 1100M intended for the construction of electric vehicles. The manuscript shows a basic understanding of the properties of DOCOL joints. This type of material is characterized by a martensitic microstructure, which makes it difficult to make a proper joint. The tensile strength, metallographic structure, and type of non-metallic inclusions were analyzed as a function of the oxygen amount in the protective gas mixture. Investigations of oxide non-metallic inclusions were carried out using scanning electron microscopy. This article attempts to obtain high joint strength of the electric vehicle structure by controlling the average size of non-metallic inclusions in the weld, which is influenced by shielding gas in the MAG welding process. The solution has application potential for the automotive industry, especially for electric vehicles.

MECHANICAL PROPERTIES OF POROUS SILICON CARBIDE CERAMICS: A REVIEW

Porous silicon carbide (SiC)-based ceramics exhibit exceptional structural and functional properties, such as excellent mechanical, chemical, and thermal stability, and controlled electrical resistivity. Owing to their superior properties, porous SiC ceramics are suitable for various industrial applications, including heatable filters, heating elements, thermoelectric energy converters, fusion reactors, thermal insulators, water purifiers, molten metal and hot gas filters, diesel particulate filters, membrane supports, and catalyst supports. A deeper understanding of the mechanical properties of porous SiC ceramics, coupled with the development of new strategies for tuning these properties, will enable the realization of numerous new applications. In this review, important factors known to determine the mechanical strength of porous SiC ceramics, such as microstructures (necking area) and pore characteristics (porosity, pore size), have been analyzed. With increasing porosity and pore size of porous SiC ceramics, the flexural strength tends to decrease. The flexural strength increases with decreasing pore size at a constant porosity, whereas the flexural strength decreases with increasing porosity at a constant pore size. In addition, the flexural strength of porous SiC ceramics is primarily influenced by the developed necking area between SiC grains, which can be obtained through the doping of soluble atoms into the SiC lattice. Based on these critical factors affecting the mechanical properties, a novel strategy for tuning the flexural strength of porous SiC ceramics is proposed.

Study the Corrosion Behavior of Low Carbon Steel Weldments Immersed in Tap Water

Corrosion is one of the main sources of failure for metals and alloys, thus it is a major engineering problem. Engineers must consider the corrosion of metals in different environments when designing engineering parts. Metals tend to corrode in different media; they show different behaviors due to differences in chemical composition and the severity of the corrosive medium. In tap water, the corrosion of mild steel products is an electrochemical phenomenon that includes two reactions: the dissolving of iron (anodic) and the reduction of oxygen (cathodic). This work observes the corrosion behavior of welded low-carbon steel by Friction Welding (FW), Shielded Metal Arc Welding (SMAW) , and MIG welding techniques using immersion tests in tap water at different periods. The results revealed that while the corrosion rate of Base Metal (BM) increases, it reaches a nearly steady state in the friction-welded and SMAW-welded samples. The difference in the corrosion rate of the welded samples can be attributed to changes in the concentrations of Cl– and CaCO3 ,as well as the pH values of the corrosive mediums. Pits could be observed in the microstructure of the nugget zone for all weldments.

Numerical simulation for gas metal arc welding: a review

Numerical simulation for gas metal arc welding: a review

Wire Arc Additive Manufacturing of Aluminum Foams Using TiH2-Laced Welding Wires.

Composite materials made from aluminum foam are increasingly used in aerospace and automotive industries due to their low density, high energy absorption capacity, and corrosion resistance. Additive manufacturing processes offer several advantages over conventional manufacturing methods, such as the ability to produce significantly more geometrically complex components without the need for expensive tooling. Direct Energy Deposition processes like Wire Arc Additive Manufacturing (WAAM) enable the additive production of near-net-shape components at high build rates. This paper presents a technology for producing aluminum foam structures using WAAM. This paper's focus is on the development of welding wires that are mixed with a foaming agent (TiH2) and produce a foamed weld metal as well as their processing using MIG welding technology.

Effect of previous heating treatments conditions and gas metal arc welding (GMAW) on mechanical and microstructural properties of HSLA steel DOMEX 460MC

Effect of previous heating treatments conditions and gas metal arc welding (GMAW) on mechanical and microstructural properties of HSLA steel DOMEX 460MC

Metal factories in the early Universe

ABSTRACT We have estimated the mass of metals in the molecular gas in 13 dusty star-forming galaxies at $z \sim 4$ in which the gas, based on previous observations, lies in a cold rotating disc. We estimated the metal masses using either the submillimetre line or continuum emission from three tracers of the overall metal content – carbon atoms, carbon monoxide molecules, and dust grains – using the first simultaneous calibration of all three tracers. We obtain very similar mass estimates from the different tracers, which are similar to the entire metal content of a present-day massive early-type galaxy. We used the dynamical masses of these galaxies to estimate an upper limit on the mass of the molecular gas in each galaxy, allowing us to estimate a lower limit on the metal abundance of the gas, finding values for many of the galaxies well above the solar value. We show that the high metal masses and metal abundances are what is expected shortly after the formation of a galaxy for a top-heavy IMF. We suggest a scenario for galaxy evolution in which massive galaxies reach a high metal abundance during their formation phase, which is then gradually reduced by dry mergers with lower mass galaxies. We show that the metals in the outflows from high-redshift dusty star-forming galaxies can quantitatively explain the long-standing puzzle that such a large fraction of the metals in galaxy clusters ($\simeq$0.75) is in the intracluster gas rather than in the galaxies themselves.

Analisa Hasil Sambungan Las ( Pipa STKM 13B Dan Plat SPH 440) Dengan Pengujian Tarik dan Photomacro

ABSTRACTGMAW (Gas Metal Arc Welding) is a fast, versatile welding technique that can be used in various positions, but it often results porosity in welded joints.This research aims to analysis of the welded joints of STKM13B pipe and SPD 440 plate using tensile and micro testing, using welding a current of 18 and varying voltages of 110, 130, and 150. The results is the shape of the welded joint of the plate and pipe is perfectly connected, the tensile test results showed that the ultimate strength values for specimen 1, 2, 3 (A110/V18, A130/V18, A150/V18) were (18,959, 27,886, 40,005 N) respectively. The highest ultimate strength values were obtained from the specimens (A150/V18) while the lowest ultimate strength value was obtained from specimen (A110/V18). The use of welding current strongly correlates with ultimate strength value and photomacro results, with higher currents resulting in higher density levels, minimizing porosity, and increasing ultimate strength. Keywords: GMAW Welding, Tensile Test, Macro Optical Test.

Microstructure, Mechanical Properties, and Wear Behavior of Dissimilar Metallic Coatings for Steel Discs of Butterfly Valves

Abstract In the present work, coating materials that can be welded to the EN 1.6220 low-alloy steel disc of a butterfly valve and are also compatible with the seal material, i.e., 17–4 PH steel, are studied. 312 duplex stainless steel, 316 austenitic stainless steel, and Stellite 6 are identified as potential coating materials for the disc based on Cobweb analysis and are welded to the disc using metal active gas (MAG) welding (312 and 316 steel coatings) and powder plasma arc welding (Stellite 6 coating). Microstructural analyses and Vickers hardness measurements of the weld joints are performed. The surface roughness and wear behavior of the coatings are also studied. Nanoscale wear phenomena and consequent phase transformations are studied using molecular dynamics simulations. The results show that 312 and 316 stainless steels are suitable coating materials for the disc.

Microstructure and mechanical properties of Al-Zn-Mg-Cu alloy fabricated by multi-wire arc-based directed energy deposition

ER5356, ER2319 and Zn wires were synchronously fed using a multi-wire gas metal arc directed energy deposition (DED) system. This allowed the successfully fabrication of Al-6.0Zn-2.5Mg-1.5Cu alloy. The microstructure and mechanical properties of the fabricated parts were studied. It is shown that the main precipitated phases are η and nanoscale η'. The upper and lower parts of the deposited parts are composed by coarse equiaxed grains and columnar dendrite structures, respectively. The average microhardness of the fabricated alloy was 118.5 HV. The ultimate tensile strength and elongations in the perpendicular to the building direction (BD) and parallel to the BD were 267 MPa and 2.7 %, 238 MPa and 2.3 %, respectively. The average tensile strength is higher than that of 7075-O alloy. The fracture mode of the samples composed brittle and ductile features, although the former dominated. This multi-wire arc DED approach provides a new choice for the in-situ synthesis of Al-Zn-Mg-Cu alloys.

Optimization of process parameters of metal inert gas welding process on aluminum alloy 6063 pipes using Taguchi-TOPSIS approach

To achieve a superior-quality weld, it is imperative to employ the appropriate welding parameters. In this study, the Taguchi-based technique for order of preference by similarity to ideal solution (TOPSIS) method has been used to improve the welding parameters such as current, voltage, and travel speed for metal inert gas (MIG) welding on the AA6063 aluminum alloy. Experiments have been performed to assess the hardness and strength characteristics of the joints. The assignment of the specimen was determined by the TOPSIS algorithm, which considers the specimen's performance score. The analysis of variance (ANOVA) approach was performed to identify the parameter with the highest significance level. A mathematical model has been established using a regression equation to establish a relationship between performance scores' signal-to-noise (S/N) ratio and process parameters. The optimal parameters for the butt joint welded using the MIG technique were determined to be a current of 120 A, a voltage of 20 V, and a travel speed of 3 cm/min. The ANOVA findings reveal that the current factor exhibits the highest level of statistical significance, accounting for 63 % of the observed variation. This was followed by voltage and travel speed, which contributed 24 % and 10.3 %, respectively. To ensure the validity of the findings, a confirmatory experiment was conducted using parameters optimized for analysis. The results of the confirmation indicate a strong alignment with the approach that was implemented.

Iron ore development management in the Russian Federation

The Russian mineral resource complex is the basis for economy real sector development. The reserves of oil, gas, ferrous and non-ferrous metals, timber, and other raw materials are the strategic basis for the state economic development stability. The subject of the study is iron ore, by reserves of which Russia is confidently among the top three countries in the world together with Australia and Brazil. The global statistics on iron ore production looks a little different since China and India are ahead of Russia in terms of production volumes after the above-mentioned countries. At a time when the country is facing the task of achieving technological sovereignty, and the metallurgical industry is the driver of developing such industries as machine building, construction, and energy, the mineral and raw materials complex development issues are of undeniable interest and relevance. The technological development strategy of Russia will rely in its implementation on a stable metallurgical industry, where issues and main directions of ferrous metallurgy development have been identified, which are the main purpose of this study.

Comparative study on mechanism of hydrogen embrittlement of Fe–18Mn-0.6C twinning-induced plasticity (TWIP) steel subjected to friction-stir welding (FSW) and tungsten inert-gas (TIG) welding

In present study, we investigated the effect of welding technique on resistance of hydrogen (H) embrittlement in Fe–18Mn-0.6C (wt.%) twinning-induced plasticity (TWIP) steel by using an electrochemical H-charging, thermal desorption spectroscope, and electron microscope. The friction-stir welding (FSW) specimen was less sensitive to H embrittlement relative to base metal and tungsten inert-gas (TIG) welding specimens by differences in microstructure and deformation mechanism. During H-charging of the FSW specimen, numerous dislocations/Σ3 boundaries reduced H diffusion into specimen interior, causing shallowest depth of brittle fracture. In contrast, the depth of brittle fracture in the H-charged TIG specimen was much larger due to rapid H diffusion by decreased grain boundaries including Σ3 annealing twin boundaries. During tensile deformation, the H-charged FSW specimen underwent the reduction in stress concentration by inactive TWIP as well as strong resistance of boundary decohesion. It was because of alleviation of H-enhanced localized plasticity (HELP) mechanism, leading to suppression of H-induced crack growth. Conversely, the H-charged base metal and TIG specimens revealed large stress concentration by active TWIP and weak boundaries owing to strong effects of HELP + H-enhanced decohesion (HEDE) mechanisms, exhibiting rapid H-induced crack propagation.