Titanium commercial alloys

The commercial product is a dull yeUow powder containing about 90% Ba02 and about 8.5% active oxygen the remainder is mainly barium carbonate and barium hydroxide. The principal use is in pyrotechnics, but there are also small uses in the curing of polysulftde mbbers and in the production of certain titanium—aluminum alloys. 

In addition to these principal alloying elements, which provide soHd solution strengthening and/or precipitation strengthening, wrought alloys may contain small amounts of titanium and boron [7440-42-8J, B, for control of ingot grain size, and ancillary additions of chromium, manganese, and zirconium to provide dispersoids. AH commercial alloys also contain iron and siUcon. 

Resistance to stress-corrosion cracking Commercially pure titanium is very resistant to stress-corrosion cracking in those aqueous environments that usually constitute a hazard for this form of failure, and with one or two exceptions, detailed below, the hazard only becomes significant when titanium is alloyed, for example, with aluminium. This latter aspect is discussed in Section 8.5 under titanium alloys. 

Investigation showed that commercial titanium alloys in contact with acid containing less than 1.34% water and more than 6% of dinitrogen tetraoxide may become sensitive to impact, and react explosively with the acid. Possible causes are discussed [1]. The spongy residue formed by prolonged corrosion of titanium-manganese alloys by red fuming nitric acid will explode on exposure to friction or heat [2],... 

Commercial alloys composition, nomenclature. A simple and general way of identification of a commercial alloy (or of a group of similar alloys) consists of a label which gives (as rounded values) the mass% contents of the main components indicated by their chemical symbols. The alloy, for instance, Ti-6A1-4V, is a titanium-based alloy typically containing 6 mass% aluminium and 4 mass% vanadium. 

More recently magnesium-base, iron-base, and zirconium-titanium-base alloys have been developed that do not require such rapid cooling. In 1992, W. L. Johnson and co-workers developed the first commercial alloy available in bulk form Vitreloy 1, which contains 41.2 a/o Zr, 13.8 a/o Ti, 12.5 a/o Cu, 10 a/o Ni, and 22.5 a/o Be. The critical cooling rate for this alloy is about 1 K/s so glassy parts can be made with dimensions of several centimeters. Its properties are given in Table 15.3. 

The experimental titanium alloy T110 produced by EBCH melting, subjected to plastic deformation and heat treatment, has characteristics of strength at a level of commercial alloy VT22, and is superior to this alloy in ductility and fatigue strength. The alloy is well-weldable with any fusion welding method. 

Titanium aluminide alloys with two compositions, and differing structures, were used as substrates. The a-2 Ti3Al was a commercial alloy (Heat T8991), fabricated as 1 mm thick sheet, by the Titanium Metals Corporation of America and contained (as w/0)... 

Table 8.1 Tensile Strengths at Low Temperatures for Several Commercial Titanium-Base Alloys [SAL79]...

Low Expansion Alloys. Binary Fe—Ni alloys as well as several alloys of the type Fe—Ni—X, where X = Cr or Co, are utilized for their low thermal expansion coefficients over a limited temperature range. Other elements also may be added to provide altered mechanical or physical properties. Common trade names include Invar (64%Fe—36%Ni), F.linvar (52%Fe—36%Ni—12%Cr) and super Invar (63%Fe—32%Ni—5%Co). These alloys, which have many commercial appHcations, are typically used at low (25—500°C) temperatures. Exceptions are automotive pistons and components of gas turbines. These alloys are useful to about 650°C while retaining low coefficients of thermal expansion. Alloys 903, 907, and 909, based on 42%Fe—38%Ni—13%Co and having varying amounts of niobium, titanium, and aluminum, are examples of such alloys (2). 

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