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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Journal Article•
TL;DR: The microstructure of AL-6XN plates joined via a double-sided friction stir weld has been investigated in this article, where the nugget has a refined structure of equiaxed grains as a result of the extreme strain and temperatures experienced during welding.
Abstract: The microstructure of AL-6XN plates joined via a double-sided friction stir weld has been investigated. The microstructural zones that develop during friction stir welding (FSW) reflect decreasing strains and less severe thermal cycles with increasing distance from the weld centerline. The nugget, located around the centerline, has a refined structure of equiaxed grains as a result of the extreme strain and temperatures experienced during welding. Several features are seen within the nugget, one of the most prominent being a steady stream of tungsten inclusions created by accelerated tool wear. The heat-affected zone consists of a mixture of relatively large austenite grains and smaller recrystallized grains present at grain boundaries. These fine grains were shown to be austenite and no evidence of sigma phase in this region was apparent. The thermal mechanical-affected zone, located between the nugget and heat-affected zone, shows a microstructural transition from the completely refined structure to a structure very similar to the base metal. Of particular importance is that, unlike fusion welding, microsegregation has been avoided during FSW. Due to the changing microstructure from base metal to the weld zone, there are corresponding changes in hardness. Moving toward the centerline from the base metal, hardness increases due to refinement of the microstructure.
20 citations
TL;DR: In this paper, a tungsten inert gas (TIG) and metal inert gases (MIG) hybrid welded joint of type 304 austenitic stainless steel was characterized with incomplete penetration, full penetration and excess penetration of weld.
Abstract: Stainless steel is a family of Fe-based alloys having excellent resistance to corrosion and as such has been used imperatively for kitchen utensils, transportation, building constructions and much more. This paper presents the work conducted on the material characterizations of a tungsten inert gas (TIG)–metal inert gas (MIG) hybrid welded joint of type 304 austenitic stainless steel. The welding processes were conducted in three phases. The phases of welding employed are MIG welding using a current of 170A, TIG welding using a current of 190A, and a hybrid TIG–MIG welding with currents of 190/170A, respectively. The MIG, TIG, and hybrid TIG–MIG weldments were characterized with incomplete penetration, full penetration and excess penetration of weld. Intergranular austenite was created toward transition and heat affected zones. The thickness of the delta ferrite (δ-Fe) formed in the microstructures of the TIG weld is more than the thickness emerged in the microstructures of MIG and hybrid TIG–MIG welds. A TIG–MIG hybrid weld of specimen welded at the currents of 190/170A has the highest ultimate tensile strength value and percentage elongation of 397.72MPa and 35.7%. The TIG–MIG hybrid welding can be recommended for high-tech industrial applications such as nuclear, aircraft, food processing, and automobile industry.
19 citations
18 citations
TL;DR: In this article, the transformation and mechanical properties of the laser continuously heat treated welds of 2205 duplex stainless steel were investigated, and it was demonstrated that the laser continuous heat treatment can eliminate the problems such as excessive ferrite and intermetallic phases and the secondary austenite can also be formed.
17 citations
References
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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