Autor: Bryan A. Chin, Y. X. Gan, Heshmat A. Aglan, R.V Steward
Rok vydání: 2001
Předmět:
Zdroj: Journal of Materials Science Letters. 20:1909-1911
ISSN: 0261-8028
Popis: Vanadium alloys are under consideration for use in fusion energy systems as structural materials for the construction of first wall and divertor because they have significant advantages over other iron based alloys in several areas. Typical advantages of the vanadium alloys include low initial level of induced activity; high strength and plasticity at elevated temperatures; high radiation strength and high corrosion resistance in liquid metals [1–3]. The first wall and divertor components of a nuclear reactor may contain kilometers of welds. Utilization of vanadium alloys in fusion reactor applications also requires dissimilar joints between vanadium alloys and other materials. Thus, vanadium alloy parts must be joined together or to lower cost dissimilar metallic alloys such as stainless steel to construct an effective and economic power generating system. There exist technical challenges in welding or brazing vanadium to vanadium or to stainless steel due to their affinity to interstitial elements such as oxygen, carbon, hydrogen and nitrogen. The hydrogen uptake of vanadium alloys after exposure in hydrogen-containing environments can result in serious degradation of ductility [4]. Compound of Ti-oxycarbonitrides (Ti-OCN) in V-Cr-Ti based alloys have been found in the form of banded grain structure which is considered as the origin of microstructural inhomogeneities [5, 6]. Arc welding processes such as gas tungsten arc (GTA), YAG and CO2 laser welding and brazing are expected to play a major role in fabrication of structures using vanadium alloys [7]. Using gettered protective gas such as argon will inevitably introduce those elements with detrimental effects. Vanadium alloy weldments produced using gas tungsten arc, laser and electron beam welding have been found to have poor toughness properties [8]. Brazing can be a viable joining process for dissimilar materials. It offers flexibility to overcome the chemical incompatibilities of dissimilar joints and provides reasonable joint strength. At the present time, vanadium alloys can be brazed under high vacuum conditions. Brazing of vanadium alloys and characterization of the brazed joints have been carried out [9]. Several filler alloys were investigated to determine the optimum braze composition to join V-5Cr-5Ti to 304 stainless steel [10]. Filler alloys based on the alloy
Databáze: OpenAIRE
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