Effect of multipass TIG welding on the corrosion resistance and microstructure of a super duplex stainless steel

Hosseini, Vahid A.; Hurtig, Kjell; Karlsson, Leif

doi:10.1002/maco.201609102

Cited by 33 publications

(35 citation statements)

References 36 publications

(37 reference statements)

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“…Nilsson et al [11] investigated the precipitation of secondary phases in different SDSS weld metals, for a selection of times and temperatures. Hosseini et al [12,13] performed multipass TIG remelting to study the precipitation of sigma phase in the heat-affected zone of a wrought SDSS alloy; however, the weld metal was not studied and the thermal cycles did not allow for studies of effects of longer heat treatments. In particular, the precipitation temperature and morphology of deleterious secondary phases need further research.…”

Section: Recommended For Publication By Commission IX -Behaviour Of Mmentioning

confidence: 99%

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Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals

et al. 2018

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Super duplex stainless steel (SDSS) weld metal microstructures, covering the complete temperature range from ambient to liquidus, were produced by arc heat treatment for 1 and 10 min. Temperature modeling and thermodynamic calculations complemented microstructural studies, hardness mapping and sensitization testing. After 1 min, intermetallics such as sigma and chi phase had precipitated, resulting in moderate sensitization at 720-840°C. After 10 min, larger amounts of intermetallics resulted in hardness up to 400 HV0.5 and more severe sensitization at 580-920°C. Coarse and fine secondary austenite precipitated at high and low temperatures, respectively: The finer secondary austenite was more detrimental to corrosion resistance due to its lower content of Cr, Mo, and N as predicted by thermodynamic calculations. Increased hardness and etching response suggest that 475°C embrittlement had occurred after 10 min. Results are summarized as time-temperature-precipitation and property diagrams for hardness and sensitization.

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Section: Recommended For Publication By Commission IX -Behaviour Of Mmentioning

confidence: 99%

“…The sensitization of duplex stainless steels is due to the low Cr and Mo contents in regions adjacent to intermetallics and nitrides and also sometimes the formation of secondary austenite with low Cr and N [12]. Sensitization testing was performed based on ASTM A262 [19], Practice A with some modification.…”

Section: Characterization Techniquesmentioning

confidence: 99%

Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals

et al. 2018

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“…Similar observations were reported by Magnabosco et al [29], where both Cr- and Mo-depleted metastable δ were attacked at the earlier aging stage. Hosseini et al [25] also observed the sensitization of δ in the vicinity of small σ particles in multiply reheated 2507 SDSS. Similarly, even 15 h of aging time at 675 °C did not heal the Cr-depleted region in 2205 DSS [43].…”

Section: Discussionmentioning

confidence: 96%

“…Sensitization screening testing was performed by electrolytically etching the cross-section in 7% oxalic acid, applying 2 V for 30 s, inspired by ASTM A262 Practice A [24], and similar to the procedure used by Hosseini et al [25]. The reason for using a low acid concentration and short etching time was to find the regions most susceptible to local corrosion attack.…”

Section: Methodsmentioning

confidence: 99%

Effect of Sigma Phase Morphology on the Degradation of Properties in a Super Duplex Stainless Steel

et al. 2018

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Sigma phase is commonly considered to be the most deleterious secondary phase precipitating in duplex stainless steels, as it results in an extreme reduction of corrosion resistance and toughness. Previous studies have mainly focused on the kinetics of sigma phase precipitation and influences on properties and only a few works have studied the morphology of sigma phase and its influences on material properties. Therefore, the influence of sigma phase morphology on the degradation of corrosion resistance and mechanical properties of 2507 super duplex stainless steel (SDSS) was studied after 10 h of arc heat treatment using optical and scanning electron microscopy, electron backscattered diffraction analysis, corrosion testing, and thermodynamic calculations. A stationary arc was applied on the 2507 SDSS disc mounted on a water-cooled chamber, producing a steady-state temperature gradient covering the entire temperature range from room temperature to the melting point. Sigma phase was the major intermetallic precipitating between 630 °C and 1010 °C and its morphology changed from blocky to fine coral-shaped with decreasing aging temperature. At the same time, the average thickness of the precipitates decreased from 2.9 µm to 0.5 µm. The chemical composition of sigma was similar to that predicted by thermodynamic calculations when formed at 800–900 °C, but deviated at higher and lower temperatures. The formation of blocky sigma phase introduced local strain in the bulk of the primary austenite grains. However, the local strain was most pronounced in the secondary austenite grains next to the coral-shaped sigma phase precipitating at lower temperatures. Microstructures with blocky and coral-shaped sigma phase particles were prone to develop microscale cracks and local corrosion, respectively. Local corrosion occurred primarily in ferrite and in secondary austenite, which was predicted by thermodynamic calculations to have a low pitting resistance equivalent. To conclude, the influence of sigma phase morphology on the degradation of properties was summarized in two diagrams as functions of the level of static load and the severity of the corrosive environment.

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“…During heating, the austenite phase is solubilized and subsequently precipitated during the cooling. Due to the fast cooling rate, the formation of austenite is impaired in the HAZ, causing excessive ferritization and coarse granulation when compared with the solubilized BM . The fast cooling of the HAZ also influences the diffusion and redistribution of alloying elements in the two phases, changing its PREN and its corrosion resistance .…”

Section: Introductionmentioning

confidence: 99%

Effect of the prior cold work on the corrosion resistance of lean duplex stainless steel welded by GMAW process

Souza

Soares

Faria

et al. 2018

Materials & Corrosion

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The influence of the prior cold work (0, 10, 30, and 30% thickness reduction) on the microstructure evolution and corrosion resistance of UNS S32304 lean duplex stainless steel (LDSS) welded by gas metal arc welding (GMAW) process was investigated. The cold work promotes flattening of the ferrite and austenite bands, deformed regions in the austenite and increase of the hardness of the material. The welding of the cold‐worked steel generated, besides the typical regions of the welded DSS joints (fusion zone (FZ), heat‐affected zone (HAZ), and base metal zone (BM)), an annealed region around the HAZ, that showed partial recovery of the microstructure and hardness reduction. The HAZ presented excessive ferritization and precipitation of chromium nitrides. The cyclic potentiodynamic polarization tests, in an aqueous solution of 3.5 wt% NaCl at room temperature, showed for the only cold‐worked samples an increase of the pitting corrosion resistance up to a level of 30% thickness reduction and a decrease of the localized corrosion for 50% thickness reduction. The welding of the cold‐worked samples promoted the reduction of pitting corrosion resistance for all levels of thickness reduction evaluated.

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Effect of multipass TIG welding on the corrosion resistance and microstructure of a super duplex stainless steel

Cited by 33 publications

References 36 publications

Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals

Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals

Effect of Sigma Phase Morphology on the Degradation of Properties in a Super Duplex Stainless Steel

Effect of the prior cold work on the corrosion resistance of lean duplex stainless steel welded by GMAW process

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