Nickel-Chromium-Molybdenum

Nickel-chromium-molybdenum alloys offer excellent corrosion resistance and good mechanical properties over a wide range of enviromnents and temperatures. CW2M, ffie cast version of Hastelloy C, is the workhorse of the group. Castings should not be called Hastelloy. The properties of the different Hastelloy alloys vary widely in specific applications. Disaster can result from use of the wrong grade. 

In addition to CW2M, there are a number of other nickel-chromium-molybdenum casting alloys. Some of the alloys are CX2MW (cast Hastelloy C22). CW6MC (cast Inconel 625), and CW6M (Chlorimet 3, trademark of Duriron Co.). 

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Alloying elements such as nickel, chromium, molybdenum, and copper, which may be introduced with scrap, can increase the hardenability, although only slightly, because the concentrations are ordinarily low. However, the heat-treating characteristics may change, and for appHcations in which ductihty is important, as in low carbon steels for deep drawing, the increased hardness and lower ductiHty imparted by these elements may be harmful. 

Low-carbon, low-alloy steels are in widespread use for fabrication-welded and forged-pressure vessels. The carbon content of these steels is usually below 0.2%, and the alloying elements that do not exceed 12% are nickel, chromium, molybdenum, vanadium, boron and copper. The principal applications of these steels are given in Table 3.8. 

Steel is essentially iron with a small amount of carbon. Additional elements are present in small quantities. Contaminants such as sulfur and phosphorus are tolerated at varying levels, depending on the use to which the steel is to be put. Since they are present in the raw material from which the steel is made it is not economic to remove them. Alloying elements such as manganese, silicon, nickel, chromium, molybdenum and vanadium are present at specified levels to improve physical properties such as toughness or corrosion resistance. 

The trade name Hastelloy covers a range of nickel, chromium, molybdenum, iron alloys that were developed for corrosion resistance to strong mineral acids, particularly HC1. The corrosion resistance, and use, of the two main grades, Hastelloy B (65 per cent Ni, 28 per cent Mo, 6 per cent Fe) and Hastelloy C (54 per cent Ni, 17 per cent Mo, 15 per cent Cr, 5 per cent Fe), are discussed in papers by Weisert (1952a,b). 

Chromium compounds Cr203 surface scale Nickel- chromium—iron alloys Nickel-chromium— molybdenum (tungsten) alloys Ni-Cr alloys analytical methods, 6 502-514 composition of metal compared to chromium ferroalloys, 6 501t dispersoid former, 2 325, 327 disposal, 6 519-521 economic aspects, 6 496—500 effect on cobalt alloys, 7 220 effect on stainless steel corrosion resistance, 7 809... 

Nickel-chromium alloys, 77 100-101 dental applications, 8 308, 310 Nickel-chromium-iron alloys, 73 519, 522 Nickel-chromium-molybdenum alloy C, in galvanic series, 7 805t... 

Nickel-chromium-molybdenum-copper-silicon alloy C, in galvanic series, 7 805t... 

Tunable uv-vis lasers, 23 144 Tuneable separation systems, 22 654 Tung oil, 9 143, 149, 150, 20 814-817 Tungstate catalysts, 22 48 Tungstates, 25 381-382 properties of, 25 382t Tungsten (W). See Nickel-chromium-molybdenum (tungsten) alloys, 25 349-376... 

Nickel-chromium-molybdenum steel 86XX and 87XX... 

Manganese-nickel-chromium-molybdenum steel 94XX... 

Most modern industrial materials are designed to be passive i.e., covered by an adherent, chemically inert, and pore-free oxide that is highly insoluble in aqueous solutions and hence dissolves at an extremely slow rate. Examples would be modern stainless steels, nickel-chromium-molybdenum, and titanium alloys. The concept of passivity is often defined by reference to the polarization curve for metals and alloys in aggressive acidic solutions, Fig. 22. This curve defines the potential regions within which the alloy would be expected to corrode actively or passively. 

Explosively clad metals, of which Deta-Clad4 is an example, are used mostly for small items such as tube sheets and heads for small heat exchangers or vessels. It is usually not economical for large surfaces or complex shapes. Nickel-chromium-molybdenum alloys and some other expensive metals can be applied to carbon steel by explosive bonding. 

NOTE Other standard specifications exist for iow carbon, manganese, molybdenum, columbium and low carbon, nickel, chromium, molybdenum, and copper high-yield strength steels. 

The trade name Hastelloy covers a range of nickel, chromium, molybdenum iron alloys that were developed for corrosion resistance to strong mineral acids. 

Elements, which usually originate from alloyed steel scrap and non-ferrous metals in the steel charge, of the type which can be added to steels as alloying elements. They include nickel, chromium, molybdenum, copper, niobium and vanadium. Residual elements... 

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