Microstructural features of dissimilar welds between 316LN austenitic stainless steel and alloy 800
15 Nov 2000-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing (Elsevier)-Vol. 292, Iss: 1, pp 74-82
TL;DR: In this article, the weld fusion zones and the interfaces with the base materials were characterised in detail using light and transmission electron microscopy, showing that the stainless steel weld metals solidified dendritically, while the 16-8-2 (16%Cr-8%Ni-2%Mo) weld metal showed a predominantly cellular substructure.
Abstract: For joining type 316LN austenitic stainless steel to modified 9Cr–1Mo steel for power plant application, a trimetallic configuration using an insert piece (such as alloy 800) of intermediate thermal coefficient of expansion (CTE) has been sometimes suggested for bridging the wide gap in CTE between the two steels. Two joints are thus involved and this paper is concerned with the weld between 316LN and alloy 800. These welds were produced using three types of filler materials: austenitic stainless steels corresponding to 316, 16Cr–8Ni–2Mo, and the nickel-base Inconel 182 1 . The weld fusion zones and the interfaces with the base materials were characterised in detail using light and transmission electron microscopy. The 316 and Inconel 182 weld metals solidified dendritically, while the 16–8–2 (16%Cr–8%Ni–2%Mo) weld metal showed a predominantly cellular substructure. The Inconel weld metal contained a large number of inclusions when deposited from flux-coated electrodes, but was relatively inclusion-free under inert gas-shielded welding. Long-term elevated-temperature aging of the weld metals resulted in embrittling sigma phase precipitation in the austenitic stainless steel weld metals, but the nickel-base welds showed no visible precipitation, demonstrating their superior metallurgical stability for high-temperature service.
Citations
More filters
TL;DR: In this paper, the authors compared welding of AISI 310 austenitic stainless steel to Inconel 657 nickel-chromium superalloy and showed that Inconels A showed the least susceptibility to hot cracking.
223 citations
TL;DR: In this article, a joint of dissimilar metals between 2205 duplex stainless steel and 16MnR low alloy high strength steel is welded by tungsten inert gas arc welding (GTAW) and shielded metal arc welding(SMAW) respectively.
145 citations
TL;DR: In this paper, a dissimilar welding between Inconel 718 nickel-base superalloy and 310S austenitic stainless steel using gas tungsten arc welding process was performed to determine the relationship between the microstructure of the welds and the resultant mechanical and corrosion properties.
138 citations
TL;DR: In this paper, microstructures of dissimilar metal welds composed of low alloy steel, Inconel 82/182 weld, and stainless steel were prepared by gas tungsten arc welding and shielded metal arc welding techniques.
135 citations
Cites background from "Microstructural features of dissimi..."
...The recrystallized features with extensive grain boundary migration [5] shown in Fig....
[...]
...Therefore, it is anticipated that large number of fine inclusions are present the Inconel 182 weld metal as reported by Sireesha [5]....
[...]
TL;DR: P-GMAW as discussed by the authors uses a higher peak current to allow one molten droplet per pulse, and a lower background current to maintain the arc stability, which can reduce the weld service life in continuous mode gas metal arc welding.
Abstract: The weld quality comprises bead geometry and its microstructure, which influence the mechanical properties of the weld. The coarse-grained weld microstructure, higher heat-affected zone, and lower penetration together with higher reinforcement reduce the weld service life in continuous mode gas metal arc welding (GMAW). Pulsed GMAW (P-GMAW) is an alternative method providing a better way for overcoming these afore mentioned problems. It uses a higher peak current to allow one molten droplet per pulse, and a lower background current to maintain the arc stability. Current pulsing refines the grains in weld fusion zone with increasing depth of penetration due to arc oscillations. Optimum weld joint characteristics can be achieved by controlling the pulse parameters. The process is versatile and easily automated. This brief review illustrates the effect of pulse parameters on weld quality.
105 citations
References
More filters
TL;DR: A transition metal joint between type 304 stainless steel and 2·25Cr-1Mo steel, with Alloy 800 as the transition piece, is being developed for application in the steam generator circuit of the 500 MW prototype fast breeder reactor.
Abstract: A transition metal joint between type 304 stainless steel and 2·25Cr–1Mo steel, with Alloy 800 as the transition piece, is being developed for application in the steam generator circuit of the 500 MW prototype fast breeder reactor. As part of this programme, the hot cracking susceptibility of Inconel 82/182 and of 16–8–2 welding consumables were compared and the microstructure and mechanical properties of butt welds between type 304 stainless steel and Alloy 800, welded by the two consumables, were studied to select the appropriate welding consumables for this joint. It is recommended that the 16–8–2 consumable should be used for welding this joint because of its lower microfissuring tendency and reduced mismatch in the coefficient of thermal expansion across the joint, although this would mean a slight adverse effect on the elevated temperature mechanical properties. Further, to select the optimum post-weld heat treatment (PWHT) of the joint between Alloy 800 and 2·25Cr–1Mo steel, welded with Inc...
22 citations
01 Aug 1962
TL;DR: In this article, the following metallurgical factors must be considered in the joining process are described: thermal cycling and shock, galvanic corrosion, metallurgy stability, compatibility of base metals, and dilution by base metal.
Abstract: General rules and precautions that were developed for joining dissimilar metals are discussed. The following metallurgical factors which must be considered in the joining process are described: thermal cycling and shock, galvanic corrosion, metallurgical stability, compatibility of base metals, and dilution by base metal. Rules for brazing and soldering are given. A table of 170 dissimilar metal joints is presented. (M.C.G.)
9 citations
Journal Article•
TL;DR: In this article, the effect of aging on impact toughness in the temperature range 600--900 C has been examined in Type ER NiCr-3 weld metal according to AWS A5.14.
Abstract: The effect of aging on impact toughness in the temperature range 600--900 C has been examined in Type ER NiCr-3 weld metal according to AWS A5.14. It was found that a toughness minimum occurred after aging for 10,000 h at 700 C. A toughness loss was also observed after aging for 10,000 h at 600 C although it was less pronounced than at 700 C (1,292 F). Microstructural investigations showed that copious precipitation occurred at 600 and 700 C. The toughness minimum observed in material aged at 700 C is ascribed to the unfavorable geometry of the precipitates formed at this temperature, leading to high stress concentrations. It is of prime importance during welding to avoid embrittling phases such as martensite. This can be achieved by using a weld metal that is rich in nickel, which suppresses the formation of martensite. One example of a nickel-base weld metal that is suitable for this purpose is Sanicro 72, which is the specification of ER NiCr-3 according to AWS A5.14. Although the as-received weld is tough, having an impact toughness of typically 220 J (163 ft-lb) at room temperature, experience has shown that some embrittlement occurs after long-term service at elevated temperatures.more » However, phenomena that could be related to the observed decrease in ductility such as reduced fatigue life at 593 C/1,098 F and premature creep failures at 566 C/1,051 F in ER NiCr-3 weld metal have been reported. Furthermore, fracture toughness tests of Alloy 718 weld metal have shown that [delta]-phase formed during aging at 566 C causes a decrease in toughness. The purpose of the present paper is to describe the microstructural changes occurring in ER NiCr-3 weld metal in order to obtain a deeper understanding of the aging-induced decrease in ductility.« less
4 citations