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 effects of applying electric and magnetic fields (static and rotating) on the laser direct metal deposition of austenitic stainless steel were investigated, and the results showed that the laser-induced plasma was strongly affected by the electromagnetic fields, which changed the cooling speed and affected the microstructure and residual stress of the deposited specimens.
Abstract: The effects of applying electric and magnetic fields (static and rotating) on the laser direct metal deposition of austenitic stainless steel were investigated. The results showed that the laser-induced plasma was strongly affected by the electromagnetic fields, which changed the cooling speed and affected the microstructure and residual stress of the deposited specimens. The electric and magnetic fields can change the solidification mode of the laser deposited austenitic stainless steel. The ferritic-austenitic mode was altered into an austenitic-ferritic mode in a rotating magnetic field, while the austenitic mode appeared in the electromagnetic fields. The hardness of the specimens increased, and the tensile stress was constrained when the specimens were manufactured in a rotating electric and magnetic field. After milling, the specimens manufactured under electric and magnetic fields had a higher compressive stress on the surface than that of the specimens produced under normal conditions.
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TL;DR: A dissimilar weld joint consisting of an austenitic stainless steel (ASS) and a martensitic steel (MSS) was obtained under optimized welding conditions by autogenous gas tungsten arc welding technique as mentioned in this paper.
15 citations
14 Jul 2016
TL;DR: In this article, an Optimum Path Forest classifier was used to detect the tertiary sigma phase in duplex stainless steels through the computational classification of induced magnetic field signals.
Abstract: Duplex stainless steels present excellent mechanical and corrosion resistance properties. However, when heat treated at temperatures above 600 ∘ C, the undesirable tertiary sigma phase is formed. This phase presents high hardness, around 900 HV, and it is rich in chromium, the material toughness being compromised when the amount of this phase is not less than 4%. This work aimed to develop a solution for the detection of this phase in duplex stainless steels through the computational classification of induced magnetic field signals. The proposed solution is based on an Optimum Path Forest classifier, which was revealed to be more robust and effective than Bayes, Artificial Neural Network and Support Vector Machine based classifiers. The induced magnetic field was produced by the interaction between an applied external field and the microstructure. Samples of the 2205 duplex stainless steel were thermal aged in order to obtain different amounts of sigma phases (up to 18% in content). The obtained classification results were compared against the ones obtained by Charpy impact energy test, amount of sigma phase, and analysis of the fracture surface by scanning electron microscopy and X-ray diffraction. The proposed solution achieved a classification accuracy superior to 95% and was revealed to be robust to signal noise, being therefore a valid testing tool to be used in this domain.
15 citations
Cites background from "Effect of weld metal chemistry and ..."
...Hence, magnetic susceptibility based tests have been applied to DSS samples with different amounts of these phases, and decreased susceptibility has been found when the thermal aging times are high due to the formation of sigma phase....
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...Thus, the sound speed is an important nondestructive parameter for following-up the hardening kinetics of DSS....
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...Electromagnetic techniques [23], such as the Eddy Current Technique (ECT) and the Saturated Low-Frequency Eddy Current (SLOFEC) technique, have been used to characterize DSS samples....
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...Duplex stainless steels (DSS) present excellent mechanical and corrosion resistance properties when the steel microstructures are only composed by austenite (γ) and ferrite (α) in approximately equal amounts [1,2]....
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...Good toughness properties can be achieved by applying proper annealing temperatures and cooling rates, which generally leads to satisfactory toughness properties in DSS [9,10]....
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TL;DR: In this paper , the impact of heat inputs and post-weld heat treatment (PWHT) on the mechanical properties, texture, microstructure and the surface of joints were analyzed.
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TL;DR: In this paper, a dissimilar welding between UNS S32205 duplex stainless steel and 316L austenitic stainless steel (ASS) was performed by using gas tungsten arc welding and ER2209 filler at two different heat inputs (0.52 and 0.98 kJ/mm).
Abstract: In the present work, dissimilar welding between UNS S32205 duplex stainless steel (DSS) and 316L austenitic stainless steel (ASS) was performed by using gas tungsten arc welding and ER2209 filler at two different heat inputs (0.52 and 0.98 kJ/mm). Microstructures were characterized using reflected light optical microscope and scanning electron microscope. Micro-hardness and tensile properties were measured across the weld for both the heat inputs. The microstructure of the welded region was primarily austenitic (for both heat inputs) with Widmanstatten morphology. The grain size of the heat affected zone on DSS side was very large (~200 µm) for the high heat input sample with the presence of partially transformed austenite and acicular austenite. The precipitation of intermetallic phases and carbides was not observed for both the heat inputs. The proportion of ferrite in the weld metal (as measured by feritscope) was higher for the high heat input sample than the low heat input sample. During the tensile test, fracture occurred in 316L ASS base metal (because of its lower strength) in ductile manner. For high heat input welds, the impact tested sample showed the presence of fine spherical precipitates rich in Cr, Mn and Fe in the fracture surface of weld metal.
15 citations
References
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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