Microstructures of gas metal arc weld metal of 950 MPa class steel

Gouda, Mohammed K.; Takahashi, Mitsuo; Ikeuchi, Kenji

doi:10.1179/174329305x40714

Cited by 27 publications

(11 citation statements)

References 27 publications

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“…The results of the studies of Gouda et al [29] and Menzel [30] above are confirmed by Ebrahimnia et al [31], who examined the effect of shielding gas composition on the welding of steel ST 37-2 with GMAW. The following four different blends of shielding gas were tested: 97.5 % Ar + 2.5 % CO 2 , 90 % Ar + 10 % CO 2 , 82 % Ar + 18 % CO 2 and 75 % Ar + 25 % CO 2 .…”

Section: Effect Of Shielding On the Microstructuresupporting

confidence: 73%

“…Gouda et al [29] found that shielding had noticeable effects on the microstructure of welded metal. Figure 11 shows the microstructure of the weld metal of 950 MPa class steel for different shielding gas mixtures.…”

Section: Effect Of Shielding On the Microstructurementioning

confidence: 99%

“…Therefore, 75 % Ar + 25 % Fig. 11 Influence of CO 2 content in argon on the microstructure of weld metal of 950 MPa class steel [29] CO 2 provided the best price-performance ratio because of its high arc efficiency and good deposition rate.…”

Section: Electrode Effect On the Shielding Gas Controlmentioning

confidence: 99%

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Effects of shielding gas control: welded joint properties in GMAW process optimization

Mvola

Kah

2016

Int J Adv Manuf Technol

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One function of shielding gases used in welding processes, such as hydrogen (H 2 ), oxygen (O 2 ), carbon dioxide (CO 2 ), nitrogen (N 2 ), helium (He), argon (Ar) and their mixtures, is protection of the weld pool against harmful contamination that could generate defects. In addition to this primary function, shielding gases significantly affect the shape of the weld, weld geometry, seam appearance, metallurgical and mechanical properties, welding speed, metal transfer, arc stability or beam and fume emissions. The shielding gas is thus a key factor in determining weld joint properties and welding process efficiency. As welding processes have become enhanced and welding research has advanced, different combinations of shielding gas mixtures have become available under a wide variety of trademarks, each claiming to offer the best efficiency. The shielding gas flow rate in GMAW welding is usually set according to empirical experiment. The flow generally remains unchanged throughout the entire welding process and is set at maximum values of the welding parameters so that there is sufficient gas cover. This setting means, however, that unnecessarily large quantities of shielding gas may be consumed in other phases of the welding process. In view of constantly increasing prices and shortfalls in helium supply, there is a need to optimize the use of shielding gas. Consequently, an ability to closely monitor the shielding gas blend and reduce waste can provide valuable cost savings. This paper examines the effects of shielding gas mixtures and their components, presents a cross-comparison of shielding effects in fusion welding and suggests guidelines for adaptive controllability of shielding gas in advanced adaptive fusion welding. The study reviews scientific case studies and experiments from the point of view of the effect of the shielding gas on the process efficiency and process outcome. The study considers shielding gases for welding of both ferrous metals (i.e. carbon steels, stainless steels, high-strength steels) and non-ferrous metals (i.e. aluminium and its alloys, nickel and its alloys and copper and its alloys). Appropriate choice of shielding gas and use of an optimum flow rate results in better quality in terms of increased productivity, reduced gas consumption and improved weld geometry properties, microstructure and mechanical properties. Although some blends can be used effectively in many different processes, other blends appear process-dependent; they produce far poorer results when utilized in non-appropriate processes. Particle image velocimetry (PIV) and Schlieren techniques can be used for visual sensing of gas flow during fusing welding. Moreover, an adaptive alternative gas supply can improve welding performance and weld quality and reduce harmful fume emission.

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Section: Effect Of Shielding On the Microstructuresupporting

confidence: 73%

Section: Effect Of Shielding On the Microstructurementioning

confidence: 99%

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Effects of shielding gas control: welded joint properties in GMAW process optimization

Mvola

Kah

2016

Int J Adv Manuf Technol

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“…The control of weld metal microstructure as well as raising the welding productivity are critical factors for the development of weld metal of high-strength steel, to secure satisfactory mechanical properties and to reduce production costs [37].…”

Section: Mechanical and Microstructural Properties Of The Welded Jointmentioning

confidence: 99%

“…However, there is a relationship between the microstructure of welds and the shielding gas, because an increase in CO 2 contributes to a coarser microstructure with a higher volume fraction of nonmetallic inclusions, besides the growth in the burn rate of alloy elements of the base metal, such as silicon and manganese. Some works have reported changes on the mechanical properties due to the decrease of these alloying elements [37,[51][52][53]. Inclusions formed in the weld metal have two opposing effects on the impact toughness.…”

Section: Mechanical and Microstructural Properties Of The Welded Jointmentioning

confidence: 99%

Influence of rotation frequency and rotation diameter on mechanical properties and microstructure of weld metal produced by MCAW-RE

Silveira

Filho

Costa

et al. 2020

Int J Adv Manuf Technol

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The MCAW process with rotating electrode (MCAW-RE) is a variation of the conventional gas metal arc welding process, which a metal-cored wire is submitted to a rotational movement along a pre-established diameter. This process enhances narrow gap welding, since the rotational motion of the electrode allows the electric arc to reach peripheral regions of the groove, preventing lack of fusion on the sidewall. As a result, reduced costs and superior productivity compared with the conventional GMAW process are obtained. The limited literature about this process is focused on the operational characteristics, and works studying the mechanical properties are not available. Thus, this work evaluates the mechanical and microstructural properties of weld metals obtained by the MCAW-RE process in order to allow a decision about its technical feasibility to replace the GMAW process in industry. Initially, beads on plate weld tests were performed with varying rotation frequency and rotation diameter, in order to determine the parameters to be used in welded joints. High-strength steel weld metals were obtained by welding performed in steel plates with dimensions of 500 × 300 × 10 mm. Mechanical tests and metallographic examination were carried out in samples removed transversally to the weld bead. The results showed that the impact toughness of the weld metals can achieve the requirements for several industrial applications. The results showed that the GMAW process with rotating electrode-cored wire has a high potential for replacement of the GMAW in industrial applications.

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Inclusions Evolution of Ca‐Treated Steel During High‐Heat Input Welding

Qi,

Pang,

et al. 2024

steel research int.

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This article has investigated a 60 mm Ca‐treated Q550 steel used for high‐heat input welding. The results have shown that the Ca‐type inclusions account for 70% of the inclusions in the steel which are mainly CaAlMg type, Ca–Al type, and a small amount of CaS type while the non‐Ca‐type inclusions are mainly FeCO. After undergoing the welding thermal cycle, the number of Ca‐containing inclusions above 2 μm in size is decreased while the number of non‐Ca‐containing inclusions below 1 μm (mainly FeO) is increased significantly. However, the total area of inclusions is decreased. It has been found out that the CaAlSO‐type inclusions undergo “diffusion” of O element to the surroundings during the thermal cycle, forming a ring‐shaped oxygen‐rich zone and carbon‐rich zone which promotes the nucleation of acicular ferrite. In contrast, the CaAlMgSO‐type inclusions undergo “decomposition” during the thermal cycle which forms a group of inclusions with different sizes and types, promoting nucleation of multioriented acicular ferrite.

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Microstructures of gas metal arc weld metal of 950 MPa class steel

Cited by 27 publications

References 27 publications

Effects of shielding gas control: welded joint properties in GMAW process optimization

Effects of shielding gas control: welded joint properties in GMAW process optimization

Influence of rotation frequency and rotation diameter on mechanical properties and microstructure of weld metal produced by MCAW-RE

Inclusions Evolution of Ca‐Treated Steel During High‐Heat Input Welding

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