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.
Citations
More filters
TL;DR: In this paper, microstructure evolution and grain boundary misorientation in coarse-grained heat-affected zone of EH420 shipbuilding steel have been investigated at different welding heat inputs.
Abstract: Microstructure evolution and grain boundary misorientation in coarse-grained heat-affected zone of EH420 shipbuilding steel have been investigated at different welding heat inputs. As heat input increases, main constituents transform from lath bainites to granular bainites, and to acicular ferrites as a result of reduced cooling rate. Corresponding fraction of high angle grain boundaries decreases from 28.24 to 20.04 pct as heat input is raised from 50 to 150 kJ/cm but reverses to 29.04 pct at 200 kJ/cm.
13 citations
TL;DR: In this paper, a gas metal arc welded (GMAW) with an ER-2209 filler wire using a gas mixture of 98%Ar + 2%O2.
Abstract: Plates, 6.3 mm thick, of 2205 duplex stainless steel (DSS) were gas metal arc welded (GMAW) under the application of an axial magnetic field (0 to 15 mT) with an ER-2209 filler wire using a gas mixture of 98%Ar + 2%O2. Microstructural characterization of the welds revealed that electromagnetic stirring (EMS) increases the content of austenite in both weld center and high temperature heat affected zone (HTHAZ). It induced a grain refining effect during freezing of the ferritic matrix which in turn enabled more sites for nucleation of austenite. This mechanism of solidification was reflected in an increase in the mechanical strength of the welds. Besides, the extent of the HTHAZ was reduced and its microhardness increased when applying the external magnetic field. It is believed that the vibration induced in this region favored the regeneration of austenite in the ferritized HTHAZ enhancing the balance of phases.
13 citations
Cites background from "Effect of weld metal chemistry and ..."
...The decrease in microhardness in the HTHAZ is due to the grain growth of δ-phase because the peak temperature reached there, dissolves the γ-phase in the ferritization temperature, coarsening the grains of the δ-phase [1, 4]....
[...]
...increasing and coarsening δ-phase [1-5]....
[...]
...This effect impacts on the mechanical properties with a large reduction in ductility due to the reduction of γ-phase and the precipitation of detrimental phases in this region [1, 4-9]....
[...]
...Instead, research efforts have focused on post-weld heat treating [1, 9, 14] or adding elemental γ-phase stabilizers [1, 4, 15-18]....
[...]
...The weld metal (WM) solidifies into coarse columnar structures virtually in a completely ferritic matrix and γ-phase grows at the ferrite grain boundaries either allotriomorphic (AA) and Widmanstätten (WA) shaped or acicular intragranularly (AcA) [1-2, 4]....
[...]
01 Jan 2006
TL;DR: Good toughness properties in base and weld material enable the use of duplex stainless steels (DSS) in critical applications as mentioned in this paper, and DSS offer high strength compared to common austenitic Stainless steels.
Abstract: Good toughness properties in base and weld material enable the use of duplex stainless steels (DSS) in critical applications. DSS offer high strength compared to common austenitic stainless steels. ...
13 citations
Cites background from "Effect of weld metal chemistry and ..."
...It was shown by Muthupandi et al [60] that the chemical composition has a great influence on the phase balance in addition to that of the cooling rate....
[...]
TL;DR: In this paper, the effect of an electron beam surface treatment on 2205 duplex stainless steel joints produced by the same electron beam process was investigated, and the results showed that the tensile properties showed considerable improvement, approaching those obtained by means of a conventional furnace heat treatment, whereas the impact strength is also improved compared to the as welded specimen, but remains clearly lower than the one of the furnace heat treated weld.
Abstract: The aim of present investigation is to study the effect of an electron beam surface treatment on 2205 duplex stainless steel joints produced by the same electron beam process Heat treatment of the joints is necessary, to re-establish the ferrite/austenite balance, which is extremely disturbed during the electron beam welding process For assessing the effectiveness of the electron beam surface treatment, similar weld joints were subjected to conventional furnace heat treatment at 1050 °C, and used as reference Metallographic techniques and mechanical testing were used to assess the microstructure and corresponding mechanical properties of the as-welded and heat treated specimens The metallographic results showed that an austenite/ferrite ratio approaching the one produced by a typical furnace post-weld heat treatment can also be achieved by heating locally the weld surface with an electron beam At the same time the tensile properties show considerable improvement, approaching those obtained by means of a conventional furnace heat treatment, whereas the impact strength is also improved compared to the as welded specimen, but remains clearly lower than the one of the furnace heat treated weld
12 citations
TL;DR: In this paper, the correlation between the microstructure and localized corrosion characteristics for a weld metal made up of 22Cr-9Ni duplex stainless steel (DSS) aged in the range of 400-1000°C for 30min was investigated.
Abstract: In this study, we investigated the correlation between the microstructure and the localized corrosion characteristics for a weld metal made up of 22Cr-9Ni duplex stainless steel (DSS) aged in the range of 400–1000 °C for 30 min. The results showed that changes in the microstructure of the DSS weldments, owing to the formation of precipitates during the aging process, affected its pitting corrosion resistance. The microstructural evolution was found to be extremely sensitive to the secondary phase precipitations such as chi (χ), sigma (σ), chromium nitride (Cr2N), and secondary austenite (γ2) in the aging range of 700–900 °C. The potentiodynamic polarization tests confirmed that the pitting potential representing the corrosion resistance decreased gradually from 500 °C, attained the lowest at 850 °C, and increased again at 900 °C. In addition, the Cr or Mo deficient area around σ phase was transformed into the secondary austenite (γ2) phase during aging where the pitting was found to occur.
12 citations
References
More filters
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