Nickel alloy weld metal

In this paper, the performanees of laser-ultrasound are estimated in order to identify lacks of weld penetration. The laser-ultrasonic technique is applied to cylindrical metallic strucmres (few mm thick) in a single-sided control. The results obtained for different materials (gold-nickel alloy and tantalum) are presented by B-sean views for which the control configuration is discussed with regard to the thermal effects at the laser impact. This testing is performed for different lacks of weld penetration (up to 0.5 mm for a thickness of 2 mm) even in the presence of the weld bead, which corresponds to an actual industrial problem. 

Eabrication techniques must take into account the metallurgical properties of the metals to be joined and the possibiUty of undesirable diffusion at the interface during hot forming, heat treating, and welding. Compatible alloys, ie, those that do not form intermetaUic compounds upon alloying, eg, nickel and nickel alloys (qv), copper and copper alloys (qv), and stainless steel alloys clad to steel, may be treated by the traditional techniques developed for clads produced by other processes. On the other hand, incompatible combinations, eg, titanium, zirconium, or aluminum to steel, require special techniques designed to limit the production at the interface of undesirable intermetaUics which would jeopardize bond ductihty. 

Bimetallic corrosion of nickel-iron alloys may be of significance in welding operations. Ni-45 Fe alloys are used as filler materials in the welding of cast irons but the favourable area relationship of weld metal to base plate... 

As with most other metal and alloys systems, nickel and certain of its alloys may suffer intergranular corrosion in some circumstances. In practice, intergranular corrosion of nickel alloys is usually confined to the vicinity of welds as a result of the effects produced by the welding operation on the structure of the material in those regions. Alloys that are subjected to other similarly unfavourable thermal treatments may also become susceptible. The compositions of most commercial nickel alloys that are marketed today are. 

General corrosion damage was the cause of failure of an A1 alloy welded pipe assembly in an aircraft bowser which was attacked by a deicing-fluid — water mixture at small weld defects . Selective attack has been reported in welded cupro-nickel subjected to estuarine and seawater environments . It was the consequence of the combination of alloy element segregation in the weld metal and the action of sulphate reducing bacteria (SRB). Sulphide-coated Cu-enriched areas were cathodic relative to the adjacent Ni-rich areas where, in the latter, the sulphides were being continuously removed by the turbulence. Sulphite ions seemed to act as a mild inhibitor. 

Nickel and Nickel Alloys Nickel is available in practically any mill form as well as in castings. It can be machined easily and joined by welding. Generally, oxidizing conditions favor corrosion, while reducing conditions retard attack. Neutral alkaline solutions, seawater, and mild atmospheric conditions do not affect nickel. The metal is widely used for... 

You may be exposed to higher levels of nickel if you work in industries that process or use nickel. You may be exposed to nickel by breathing dust or fumes (as from welding) or by skin contact with nickel-containing metal and dust or solutions containing dissolved nickel compounds. A national survey conducted from 1980 to 1983 estimated that 727,240 workers are potentially exposed to nickel metal, nickel alloys, or nickel compounds. 

Corrosion-resistant metals and alloys, including stainless steels, nickel alloys, titanium, zirconium, and tantalum can be applied as linings or claddings to cheaper steel substrates. Most (>90%) are applied by roll bonding, but weld overlaying and explosive bonding are also used, as appropriate. Particularly expensive metals, such as tantalum, can be used as very thin ( 0.5 mm) loose linings. 

Aluminum, copper, and other face-centered cubic metals and alloys (such as the austenitic stainless steels and nickel-base alloys) do not become brittle at low temperatures, except if heavily cold worked. Most such alloys are exempt from impact testing for design temperatures down to -320°F (-195°C). Some types, such as Type 304, are exempt down to 25°F (-255°C). The exemption temperatures for weld metals and HAZs are usually higher than those for the parent metal. 

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