A specimen of weld metal was prepared by GTA welding with weld wire of super duplex stainless steel. Aging treatment was conducted for the sample at the temperature range of 700 to for 5 to 300 minutes. The effect of aging temperature and time to pitting corrosion of weld metal has been investigated and the results were derived as follows. The volume fraction of phase tends to increase with an increase of aging temperature and time. Pitting potential Ep representing pitting corrosion was found to tend to decrease with an increase of aging time at 700 to . And most of the pits formed near the -phase in the ferrite and seemed to propagated to austenite.
Abstract Pitting corrosion resistance of 2304 duplex stainless steels after autogenous plasma-arc welding and subsequent short-time post-weld heat treatment at different temperatures, determined by critical pitting temperature in 1.0 M NaCl solution, has been investigated. The results showed that the as-welded joint displayed impaired pitting corrosion resistance and that pitting preferentially occurred at ferrite grain in heat-affected zone near the fusion line. Short-time annealing treatment a...
Abstract In this study, the influence of various concentrations of dichromate ( Cr 2 O 7 2 - ) and chloride ions on critical pitting temperature (CPT) of duplex stainless steel 2205 (DSS 2205) is investigated by employing potentiodynamic and potentiostatic CPT measurement methods. Potentiostatic results indicate that by adding 0.01 M Cr 2 O 7 2 - to 0.1 M NaCl solution the CPT raised by 12 °C. Based on potentiodynamic CPT measurements in the solutions with ( Cr 2 O 7 2 - ) / ( Cl - ) ratio equal...
In this study effect of different ageing conditions on intergranular corrosion, pitting corrosion and relation between critical pitting temperature (CPT) and degree of sensitisation (DOS) was investigated by potentiostatic polarisation and double loop-EPR methods. The results showed by increasing sensitisation time, DOS increased and measured CPT value decreased. In addition the values of DOS and CPT of specimens aged at 650 °C showed almost liner relation while this correlation was diminished f...
Abstract Effect of aging at 850 °C on pitting corrosion of UNS S31803 duplex stainless steel was examined in chloride solution by potentiostatic critical pitting temperature (CPT) measurements. The quantitative metallography coupled with X-ray diffraction technique was employed to follow the microstructure evolution. Moreover, the initiation and propagation of pitting corrosion had been imaged in relation to microstructure variations using scanning electron microscopy (SEM). The results demonstr...
Last. H.F.G. de Abreu(UFC: Federal University of Ceará)H-Index: 11
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Abstract In the present work, the effect of grain size on deleterious phase precipitation in a superduplex stainless steel was investigated. The materials studied were heat treated isothermally at 800 °C, 850 °C and 900 °C for times up to 120 min. Hardness tests, light optical microscopy, scanning electron microscopy and X-ray diffraction were carried out to detect sigma and other harmful precipitate phases. The ferritic and austenitic grain sizes in the solution treated condition of the two ste...
Last. J.A. de Souza(Federal Fluminense University)H-Index: 6
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Abstract The superduplex stainless steels have an austeno-ferritic microstructure with an average fraction of each phase of approximately 50%. This duplex microstructure improves simultaneously the mechanical properties and corrosion resistance. Welding of these steels is often a critical operation. In this paper we focus on characterization and analysis of a multipass weld joint of UNS S32750 steel prepared using welding conditions equal to industrial standards. The toughness and corrosion resi...
The transition from metastable to stable pitting was studied in 0.5 M NaCl water solution for two cast duplex stainless steels under different microstructural conditions achieved by annealing in the range from 900 °C to 1200 °C. The ensuing microstructural changes in heat treated steels were defined and correlated with established pitting potentials (Ep) and sites of corrosion damage initiation. The variations in Ep have been discussed in terms of secondary phases precipitation. The critical con...
Abstract Effects of σ phase on the initiation and propagation of pitting corrosion of duplex stainless steel were examined using critical pitting temperature (CPT) and electrochemical noise measurements in a ferric chloride solution, and the results were discussed with microstructural variations with aging time. Power spectral density (PSD) and corrosion admittance (Ac) spectrum as measures of the severity of localized corrosion were used to analyze the electrochemical noise quantitatively. With...
A deposited metal specimen of ER2594 which is a super duplex steel welding wire used to investigate the effect of sigma() phase on electrochemical corrosion characteristics was prepared by gas tungsten arc welding. Aging treatment was conducted for the specimen at the temperature range of to for 5 to 300 minutes after annealing at . Corrosion current density has decreased a little with an increase of aging time over 60 minutes at to and the uniform corrosion of deposited metal had more influence...
