Corrosion Resistance and Mechanical Properties of TIG and A-TIG Welded Joints of Lean Duplex Stainless Steel S82441 / 1.4662

Abstract

CorrosIon resIstanCe and meChanICal propertIes of tIG and a-tIG welded joInts of lean duplex staInless steel s82441 / 1.4662This paper presents results of pitting corrosion resistance of TIG (autogenous and with filler metal) and a-TIG welded lean duplex stainless steel S82441/1.4662 evaluated according to aSTM G48 method, where autogenous TIG welding process was applied using different amounts of heat input and shielding gases like pure ar and ar+N2 and ar+He mixtures. The results of pitting corrosion resistance of the welded joints of lean duplex stainless steel S82441 were studied in as weld conditions and after different mechanical surface finish treatments. The results of the critical pitting temperature (CPT) determined according to aSTM G48 at temperatures of 15, 25 and 35°C were presented. Three different surface treatment after welding were applied: etching, milling, brushing + etching. The influence of post weld surface treatment was studied in respect to the pitting corrosion resistance, basing on CPT temperature.Research on TIG welding of lean duplex stainless steel S82441/1.4662 showed a clear influence of the applied shielding gas mixtures, where the addition of 5 to 15% N2 to ar virtually no effect on the level of resistance to pitting corrosion, only 5% N2 addition has a positive effect, while use of a mixture of 50% ar + 50% He compared with welding at 100% ar atmosphere, can significantly reduce the resistance to pitting corrosion. Definite good results were obtained during TIG welding with the participation of activation flux (a-TIG). The weld surface of lean duplex stainless S82441/1.4662 obtained in a-TIG welding without the addition of filler metal has a much lower tendency to pitting corrosion than traditional welds made by TIG method. Pitting corrosion resistance of welds made by a-TIG improved with the increase of the heat input in the tested range of welding current 100-200 a. It was also found that the intensity of the occurrence of pitting does not affect the method of cleaning welds after welding, but the mechanical removal of a thin surface layer of metal significantly reduces their intensity.

Microstructural, Mechanical, and Electrochemical Analysis of Duplex and Superduplex Stainless Steels Welded with the Autogenous TIG Process Using Different Heat Input

“…Applied to oil extraction structures, pipes, and pressure vessels, these steels combine good mechanical properties with an excellent ability to withstand the corrosive media to which they are exposed. These characteristics are directly linked to the biphasic structure formed, composed basically of ferrite and austenite in approximately equal proportions [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. For the application of these steels, welding processes are usually involved, and weldability is another positive point, as DSS and SDSS are weldable by almost all processes available in the market.…”

“…The filler metals are manufactured to compensate possible losses of alloying elements during welding of base metal (BM), and their chemical composition is always similar to the base metal to be welded [5]. Although the literature considers the use of filler metal as indispensable, some studies have been carried out without the addition of filler metal [6]. In practice, in some situations in the field where the repair in steel is necessary, the professional can have only the option of autogenously welding.…”

The Service Life of the Repair Welded Joint of Cr-Mo / Cr-Mo-V

“…At present, the time of operation of the majority of Polish power stations and heat and power generating plants, frequently beyond 200,000 h, results in aiming the main efforts to maintain the level of electric energy production in Poland at the extension of operation much beyond the design work time with simultaneous modernisation of boilers and turbines in order to improve their technical and economic indicators (by increasing the power and improving the efficiency and availability), extend their service life, and, above all, reduce the emission of harmful pollutants to the atmosphere, water and soil [1][2][3][4].…”

Mechanical Properties of High-Mn Austenitic Steel Tested under Static and Dynamic Conditions

“…The modern quality requirements for automotive vehicles and other means of transport relate primarily to implementation of programmes improving the passive safety of traffic users, to possibly lowest weight of vehicles and to the resulting reduction in fuel consumption and in the related emission of fumes into the air, as well as to comfort, aesthetics and many other aspects. It is claimed according to the views presented at present [8][9][10] that new steels with an austenitic A1 structure containing Mn at a concentration of above 25% and Si and Al may ensure significant progress, especially in automotive applications [1][2][3][4], as opportunities have already been practically exploited to improve strength and plasticity for steel with an A2 lattice structure -ferritic and martensitic steels (hsLA type -high strength Low Alloy steels, bh type -bake hardening steels, IF type -Interstitial Free, IS type -Isotropic Steels, multiphase steels of DP type -Dual Phase, TriP type -Transformation induce Plasticity steels, cP type -complex Phase, PM typePartially Martensitic steels and Ms type -Martensitic steels) [1,[4][5][6][7][22][23][24][25][26][27][28][29][30][31][32]. Steels containing 22-35% of Mn exhibit a fully stable austenite structure, and at a concentration of more than 25% Mn, they show plasticity induced by mechanical twinning during cold plastic deformation, called the TWiP effect.…”