Effect of the Addition of Nickel Powder and Post Weld Heat Treatment on the Metallurgical and Mechanical Properties of the Welded UNS S32304 Duplex Stainless Steel

Tahaei, Ali; Pérez, A. F. Miranda; Merlin, Mattia; Valdes, Felipe Arturo Reyes; Garagnani, Gian Luca

doi:10.1590/0104-9224/si2102.09

Cited by 20 publications

(16 citation statements)

References 27 publications

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“…The area fraction was directly proportional to the volume fraction. In accordance with the investigations, it was possible to observe different types of austenite produced by the subsequent transitions of the solid-state ferrite phase, which solidified through the melted metal: grain boundary austenite (GBA), Widmanstätten austenite (WA), intragranular austenite (IGA), and partially transformed austenite (PTA) [24] (Figures 5 and 6).…”

Section: Preliminary Testssupporting

confidence: 73%

“…The initial analysis of the joint showed that the high nickel concentration in the interface of the DSS employing a welding current of 130 A was a result of the lack of heat in the mentioned zone (Figure 4), preventing the diffusion of this element through the joint. Additionally, the microstructural study revealed the formation of four different types of primary austenite in the HAZ and FZ of both steels (Figures 5 and 6): grain boundary austenite (GBA), Widmanstätten austenite (WA), intragranular austenite (IGA), and partially transformed austenite (PTA) [13,24].…”

Section: Discussionmentioning

confidence: 99%

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Maintenance of the Austenite/Ferrite Ratio Balance in GTAW DSS Joints Through Process Parameters Optimization

Rodriguez¹,

Miranda²,

González

et al. 2020

Materials

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The present work describes the influence of the parameters employed in the gas tungsten arc welding process (GTAW) when nickel powder is used as a filler metal in 2304/2507 duplex stainless-steel dissimilar joints. Multi-objective optimization was applied in order to maintain the austenite/ferrite percentage in the welded zone. A microstructural and phase quantification analysis was performed in each sample through optical and scanning electron microscopes. It was found that a nickel powder addition combined with low heat input increased the biphasic ratio across the different zones of the dissimilar welded samples. Although the austenite volume fraction increased in the 2304 heat-affected zone (HAZ) near to 25%, it was not sufficient according to international standards. The obtained results led to the maintenance of the 50/50 phase percentage in the 2507 HAZ welded joint side, as well as to the increment of the austenite percentage in the 2304 HAZ.Materials 2020, 13, 780 2 of 14 temperatures, another phenomenon is observed: ferrite decomposition occurs, causing the formation of harmful secondary phases, such as sigma (σ), chi (χ), carbides, and nitrides phases, which subsequently deteriorate the mechanical and corrosion-resistance properties of the DSS. Santos et al. conducted a study, based on the analysis of thermal history, which showed the temperature measured across the weld and its effect on the microstructural and mechanical behavior, and compared the results with the three-dimensional finite element model built. In addition, Sarlak, Atapour, and collaborators specifically studied the corrosion behavior across the welding in samples obtained by the welding process of a lean duplex stainless steel (LDSS) and its effect on the microstructure [9][10][11].Various joining techniques, such as plasma, laser, tungsten inert gas (TIG), and gas metal arc welding (GMAW) are being developed to meet the requirements demanded by these materials, avoiding distortion. However, ferritization is a problem with these processes. In addition, the effect generated by the entry of heat into these materials is a research topic. Plasma arc welding has beneficial results for DSS, which is situated at a controlled heat input and an acceptable ferrite ratio compared with other processes. Flux-cored arc welding (FCAW) has gradually attracted strong attention in welding DSS due to its higher welding efficiency compared with the gas tungsten arc welding process (GTAW) process. However, studies on the microstructure, mechanical properties, and corrosion resistance of the DSS FCAW joint are limited. Advanced laser hybrid welding has a great advantage for DSS, because it reduces heat input and distortion level compared with SAW and FCAW [12,13]. The GTAW is a welding procedure that has been employed efficiently in past years to weld materials such as stainless steels due to its facility to produce sound joints that meet specific requirements of industries, added to its facility to work when thin materials are required. However, it has be...

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Section: Preliminary Testssupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Maintenance of the Austenite/Ferrite Ratio Balance in GTAW DSS Joints Through Process Parameters Optimization

Rodriguez¹,

Miranda²,

González

et al. 2020

Materials

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“…The percentages of austenite are significantly affected by the addition of nitrogen in the shielding gas and this leads to changes in the total austenite content after the welding process. About N 2 supplementation in the shielding gas, the increase of the austenite content in the SZ was shown: 22% to 37% and HAZ: 23% to 25.3%, which agrees with the results of Tahaei et al 35 and Zhang et al, 15 .…”

Section: Resultssupporting

confidence: 90%

Effect of Nitrogen Addition to Shielding Gas on Cooling Rates and in the Microstructure of Thin Sheets of Duplex Stainless Steel Welded by Pulsed Gas Tungsten Arc Welding Process

et al. 2019

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The effect of the nitrogen content in the shielding gas and its effect on temperature distributions at the welded zone of thin sheets of duplex stainless steel have been evaluated. The duplex stainless steels have many features due to unique microstructural combination of austenite and ferrite grains. The phase balance can be easily shifted depending on the welding parameters. Two sheets were welded using pure argon and pure argon plus 2% of nitrogen as shielding gas. The thermal profile had shown that N 2-supplemented shielding gas lead to higher peaks of temperature using similar welding parameters. Microstructural examination showed that the austenite phase in the weld increased with the presence of nitrogen in the shielding gas. The added nitrogen promoted primary austenite formation and slightly increases the microhardness at the solidified zone. Microhardness mapping and metallographic imaging presented information about microstructures, confirming the formation of secondary phases during thermal cycle in the temperature range 850 °C and 950 °C. Control of ferrite amounts in the welds is essential mainly to improve mechanical properties and corrosion resistance of welding zones.

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“…This effect is a consequence of more austenite-promoting elements in the fusion zone. As already mentioned, phase balance in SDSS is very important for the material to maintain its mechanical resistance and corrosion properties [27,28,29,30].…”

Section: Discussionmentioning

confidence: 99%

Nd: YAG Pulsed Laser Dissimilar Welding of UNS S32750 Duplex with 316L Austenitic Stainless Steel

et al. 2019

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Duplex stainless steels (DSSs), a particular category of stainless steels, are employed in all kinds of industrial applications where excellent corrosion resistance and high strength are necessary. These good properties are provided by their biphasic microstructure, consisting of ferrite and austenite in almost equal volume fractions of phases. In the present work, Nd: YAG pulsed laser dissimilar welding of UNS S32750 super duplex stainless steel (SDSS) with 316L austenitic stainless steel (ASS), with different heat inputs, was investigated. The results showed that the fusion zone microstructure observed consisted of a ferrite matrix with grain boundary austenite (GBA), Widmanstätten austenite (WA) and intragranular austenite (IA), with the same proportion of ferrite and austenite phases. Changes in the heat input (between 45, 90 and 120 J/mm) did not significantly affect the ferrite/austenite phase balance and the microhardness in the fusion zone.

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Effect of the Addition of Nickel Powder and Post Weld Heat Treatment on the Metallurgical and Mechanical Properties of the Welded UNS S32304 Duplex Stainless Steel

Cited by 20 publications

References 27 publications

Maintenance of the Austenite/Ferrite Ratio Balance in GTAW DSS Joints Through Process Parameters Optimization

Maintenance of the Austenite/Ferrite Ratio Balance in GTAW DSS Joints Through Process Parameters Optimization

Effect of Nitrogen Addition to Shielding Gas on Cooling Rates and in the Microstructure of Thin Sheets of Duplex Stainless Steel Welded by Pulsed Gas Tungsten Arc Welding Process

Nd: YAG Pulsed Laser Dissimilar Welding of UNS S32750 Duplex with 316L Austenitic Stainless Steel

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