Other Nickel-Based Alloys

N7M is the cast equivalent of Hastelloy B2. This nickel-molybdenum alloy has excellent corrosion resistance in all concentrations and temperatures of hydrochloric acid. If ferric or cupric ions are present, however, severe attack will occur. It is also good for sulfuric, acetic, and phosphoric acids.  

CYSSnBiM is a proprietary alloy known as Waukesha 88 (trademark of Waukesha Foimdry). Tin and bismuth are added as solid metal lubricants for improved galling resistance. It is primarily used in the food industry to prevent galling against SST. Weld repairs are prohibited. It is not as corrosion-resistant as other nickel-based alloys however, it performs well in food-industry applications. 

Gossett. 1988. Improved high-nickel alloy castings. Materials Performance, 27 12, 44 7. 

Gossett. 1989. Reliable base for high nickel equipment. Chemical Engineering, November, 145-148. 

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Plain Carbon and Low Alloy Steels. For the purposes herein plain carbon and low alloy steels include those containing up to 10% chromium and 1.5% molybdenum, plus small amounts of other alloying elements. These steels are generally cheaper and easier to fabricate than the more highly alloyed steels, and are the most widely used class of alloys within their serviceable temperature range. Figure 7 shows relaxation strengths of these steels and some nickel-base alloys at elevated temperatures (34). 

Pla.tinum, Platinum plating has found appHcation in the production of platinised titanium, niobium, or tantalum anodes which are used as insoluble anodes in many other plating solutions (see Metalanodes). Plating solutions were often based on platinum "P" salt, which is diamminedinitroplatiniim (IT). A dinitroplatinite sulfate—sulfuric acid bath has been used to plate direcdy onto titanium (129). This bath contains 5 g/L of the platinum salt, pH adjusted to 2.0 with sulfuric acid. The bath is operated at 40°C at 10—100 A/m. Other baths based on chloroplatinic acid have been used in both acid and alkaline formulations the acid bath uses 20 g/L of the platinum salt and 300 g/L hydrochloric acid at 65° C and 10—200 A/m. The alkaline bath uses 10 g/L of the platinum salt, 60 g/L of ammonium phosphate and ammonium hydroxide to give a pH of 2.5—9.0. The alkaline bath can be plated directly onto nickel-base alloys acid baths require a gold strike on most metals. 

Steels and stainless steels show preferential nucleation of pits at inclusions, most notably sulphide inclusions ". Other sulphur-rich regions in ferrous and nickel-based alloys may also lead to premature failure. It has been shown that accumulation of sulphur on the surface of these materials retards passivity and enhances dissolution of the metal. These effects occur in any solution in which the metal shows an active region and they are also preferential pitting sites in the presence of chloride. A recent notion for... 

While the few examples quoted provide some general guidance as to the behaviour of nickel-rich materials in contact with molten metals and salts, it cannot be over-emphasised that such behaviour can be very considerably modified by the presence of very small amounts of contaminants in the liquid media (see Sections 2.9 and 2.10). The effect of very small contents of sodium chloride on the corrosion of nickel-base alloys by sodium sulphate has been referred to previously and other reported examples involving trace amounts, particularly of gaseous impurities, underline the need for great care in interpretation of experimental results. 

Of the weldability problems, nickel and nickel-based alloys are particularly prone to solidification porosity, especially if nitrogen is present in the arc atmosphere, but this may be controlled by ensuring the presence of titanium as a denitrider in the filler and maintaining, a short arc length. The other problem that may be encountered is hot cracking, particularly in alloys containing Cr, Si, Ti, Al, B, Zr, S, Pb and P. 

Other members of the medium-alloy group do not have ACI designations but are listed in ASTM specifications (refer to ASTM A 494) such as Incoloy 825 and Hastelloy G-3 and G-30. Several nickel-based alloys that are normally only wrought have cast equivalents but are not listed in any specifications. Hastelloy G-3 contains 44 percent... 

Chapter 10 provides an exhaustive description of how these techniques can be applied to a large number of industrial alloys and other materials. This includes a discussion of solution and substance databases and step-by-step examples of multi-component calculations. Validation of calculated equilibria in multi-component alloys is given by a detailed comparison with experimental results for a variety of steels, titanium- and nickel-base alloys. Further selected examples include the formation of deleterious phases, complex precipitation sequences, sensitivity factor analysis, intermetallic alloys, alloy design, slag, slag-metal and other complex chemical equilibria and nuclear applications. 

However, it became evident in the post-war period that, valuable as they were, these band-structure concepts could not be applied even qualitatively to key systems of industrial interest notably steels, nickel-base alloys, and other emerging materials such as titanium and uranium alloys. This led to a resurgence of interest in a more general thermodynamic approach both in Europe (Meijering 1948, Hillert 1953, Lumsden 1952, Andrews 1956, Svechnikov and Lesnik 1956, Meijering 1957) and in the USA (Kaufman and Cohen 1956, Weiss and Tauer 1956, Kaufman and Cohen 1958, Betterton 1958). Initially much of the work related only to relatively simple binary or ternary systems and calculations were performed largely by individuals, each with their own methodology, and there was no attempt to produce a co-ordinated framework. 

The most important application of chromium is in the production of steel. High-carbon and other grades of ferro-chomium alloys are added to steel to improve mechanical properties, increase hardening, and enhance corrosion resistance. Chromium also is added to cobalt and nickel-base alloys for the same purpose. 

The most important applications of nickel metal involve its use in numerous alloys. Such alloys are used to construct various equipment, reaction vessels, plumbing parts, missile, and aerospace components. Such nickel-based alloys include Monel, Inconel, HasteUoy, Nichrome, Duranickel, Udinet, Incoloy and many other alloys under various other trade names. The metal itself has some major uses. Nickel anodes are used for nickel plating of many base metals to enhance their resistance to corrosion. Nickel-plated metals are used in various equipment, machine parts, printing plates, and many household items such as scissors, keys, clips, pins, and decorative pieces. Nickel powder is used as porous electrodes in storage batteries and fuel cells. 

A large number of copper-base and nickel-base alloys (such as cupro-nickels, Monel, and aluminum brass) have been used in sea-water service with success. Special materials such as Hastelloy C, Illium, and titanium are available for extremely corrosive situations. The evidence, so far, indicates titanium to be outstanding and to rank above other commercially available metals in corrosion resistance under conditions involving high temperature, velocity, and other adverse environmental conditions. 

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