Effect of weld metal chemistry and heat input on the structure and properties of duplex stainless steel welds
15 Oct 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing (Elsevier)-Vol. 358, Iss: 1, pp 9-16
TL;DR: In this article, a low heat input process viz., EBW and another commonly employed process, gas tungsten-arc welding have been employed for welding of duplex stainless steels with and without nickel enhancement.
Abstract: The excellent combination of strength and corrosion resistance in duplex stainless steels (DSS) is due to their strict composition control and microstructural balance. The ferrite–austenite ratio is often upset in DSS weld metals owing to the rapid cooling rates associated with welding. To achieve the desired ferrite–austenite balance and hence properties, either the weld metal composition and/or the heat input is controlled. In the current work, a low heat input process viz., EBW and another commonly employed process, gas tungsten-arc welding have been employed for welding of DSS with and without nickel enhancement. Results show that (i) chemical composition has got a greater influence on the ferrite–austenite ratio than the cooling rate, (ii) and even EBW which is considered an immature process in welding of DSS, can be employed provided means of filler addition could be devised.
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TL;DR: In this paper, the effect of using electrolytic nickel foils as an addition metal on UNS S32750 SDSS Nd:YAG pulsed laser welding, through the evaluation of the microstructure, hardness, tensile strength, and corrosion resistance of the weld bead.
Abstract: Super-duplex stainless steel (SDSS) exhibits an austenite-ferrite dual-phase structure, which promotes many benefits upon single-phase grades, such as high mechanical strength and corrosion resistance. Welding process results in an unbalanced microstructure, with large amount of ferrite, which compromise SDSS’s properties. This paper investigates the effect of using electrolytic nickel foils as an addition metal on UNS S32750 SDSS Nd:YAG pulsed laser welding, through the evaluation of the microstructure, hardness, tensile strength, and corrosion resistance of the weld bead. Six conditions were investigated: autogenous welding and with addition of nickel, varying the thickness of nickel foil added. Microstructural analysis reveals an increase in volume fraction of austenite for the conditions with addition of nickel. Using a 30 µm thick nickel foil, approximately equal amount of austenite and ferrite was obtained in the weld bead. The higher microhardness was obtained for the autogenous welding, 400 HV and decreased with the addition of nickel. The tensile strength decreased 4% in the experimental conditions with high nickel addition. The corrosion resistances were the same for all the conditions with addition on nickel, regardless of the nickel foil thickness added, but it compared to autogenous welding the CPT’s increased approximately 14 °C.
4 citations
10 Oct 2018
4 citations
TL;DR: In this paper, the isothermal and cyclic oxidation behavior of the 1.4742 ferritic and 310S austenitic stainless steels together with their dissimilar metal welds was investigated in the air with the humidity of 30'±'3%.
Abstract: In the present work, the isothermal and cyclic oxidation behaviour of the 1.4742 ferritic and 310S austenitic stainless steels together with their dissimilar metal welds was investigated in the air with the humidity of 30 ± 3%. The welding was performed by the gas tungsten arc welding process utilizing ER310, ERNiCr-3, and ER446 filler metals. In the isothermal conditions, all the tested specimens followed the parabolic rate law. The maximum and minimum kp values were related to the 310S-BM, 1.89 × 10−1 mg2 cm−4 h−1, and the 1.4742-BM, 0.03 × 10−2 mg2 cm−4 h−1, respectively. Due to the formation of a dense and thin mono-layer of Cr–Fe–Al spinel ((Cr,Fe,Al)3O4) on the surface of the 1.4742 stainless steel alongside the lowest coefficients of the thermal expansion (CTE), it exhibits a highly satisfying oxidation resistance in both isothermal and cyclic conditions. In the cyclic conditions, except for the 1.4742-BM, the other specimens encountered the oxide scale cracking and spallation. The large CTE mismatch between the underlying 310S-BM, -BMS, and ER310-WM with the multi-layer chromia (Cr2O3) and Cr–Mn spinel ((Cr,Mn)3O4) oxide scale caused extensive spallation and mass loss in cyclic conditions. The ERNiCr-3-W in comparison with the two other weldments, by reducing the thermal expansion mismatch between the adjacent underlying metals and the better oxidation resistance of the nickel-base ERNiCr-3-WM, showed better oxidation resistance in both isothermal and cyclic conditions.
3 citations
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Book•
01 Jan 1997
TL;DR: In this paper, the authors present a non-destructive testing of welds for service experience, based on the application of service experience in metallurgy and metallurgical applications.
Abstract: Developments, grades and specifications Alloy design Microstructure Forming and machining Physical and mechanical properties Corrosion Stress corrosion cracking Welding metallurgy Welding processes Weld properties Non-destructive testing of welds Applications Service experience.
449 citations