Ferrous alloys Iron Steels

Applicable material Ferrous alloys, carbon steels, alloy steels, cast irons Same... 

Metallui ical. The metallurgical appfications of selenium normally involve its use as a minor alloying additive to enhance the properties of both ferrous and nonferrous metals and alloys (see Iron Steel). 

Cast iron is the term applied to a wide range of ferrous alloys, whose principal distinguishing feature is a carbon content in excess of l -7<7o. The relatively low melting point of these alloys compared with that of steels and their tendency to expand slightly on solidification, which make them admirably suited for the production of components by casting, result from this feature of their composition. 

Whereas ductile materials, such as iron and mild steel, are often considered not to crack when charged with hydrogen and subjected to a tensile stress below the yield stress, the position is different with high-strength ferrous alloys where, depending on the strength of the steel and the hydrogen content, failure may occur well below the yield stress. However, the fracture process is not instantaneous and there is a time delay before cracks are... 

Little, M. V., Bonding Aluminium To Ferrous Alloys , Machinery, N. Y., 56, 173 (1950) Drewett, R., Diffusion Coatings for the Protection of Iron and Steel , Part I, Anti-Corrosion, 16 No. 4, 11-16, April (1969)... 

In this connection it must be pointed out that standard samples which have been analysed by a number of skilled analysts are commercially available. These include certain primary standards (sodium oxalate, potassium hydrogenphthalate, arsenic(III) oxide, and benzoic acid) and ores, ceramic materials, irons, steels, steel-making alloys, and non-ferrous alloys. 

The metal casting industry conventionally divides casting products into ferrous and nonferrous metals, in particular, iron-based, steel-based, aluminum-based, and copper-based castings. The other castings of low fractions include magnesium, lead, zinc, and their alloys. In the U.S., the foundry industry currently produces 11 million tons of metal product per year, with a shipment value of 19 billion. Of them, iron and steel accounted for 84% of metals cast.5 The remaining 15% of foundry operations are concerned with aluminum, copper, zinc, and lead production. Table 4.2 summarizes critical physical and thermal properties of aluminum, iron/steel, and cast iron. 

Ferrous Alloys. Many ancient objects allegedly made of iron actually consist not of the pure metal but of alloys of iron and carbon known by the generic name ferrous alloys. These can be broadly classified into two classes steel and cast iron. Steel is the common name for iron-carbon alloys in which the relative amount of carbon ranges between 0.03% and 2%. If the relative amount of carbon in the alloy exceeds 2%, the alloy is known as cast iron (see Table 33) (Angus 1976 Wertime 1961). Steel is outstanding because of the mechanical properties that it acquires when subjected to heat treatment, which causes changes in its structure and physical properties (see Textbox... 

IRON/STEEL NON-FERROUS CARBON PERMANENT CATALYST INDUSTRY. ALLOY. ARC MAGNETS. CHEMICALS. 

In general, ferrous alloys are difficult to dissolve with acids so that a fusion, for example with sodium/potassium carbonate, is recommended. The resulting high salt concentration can produce difficulties (viscosity, nebuliser/ burner system), as is discussed in Chapter 3. Once sample solutions are available, there is no difference in analysis from the methods for iron and steel. 

Next we consider the Pourbaix diagram for iron, which is, of course, of paramount importance for the understanding of corrosion of ferrous alloys such as the many types of steel and stainless steel. This is a rather complex diagram, since two oxidation states of iron exist both in the liquid and the solid state and the metal is amphoteric to some extent. Figure 16M is a simplified version of the diagrams shown in the original work of Pourbaix. The two soluble species in acid solutions are Fe and Fe. The relevant equilibria are... 

Inorganic inhibitors such as chromate, nitrite, nitrates, and arsenate are very efficient for ferrous alloys. They prevent stainless steel pitting corrosion by forming a monolayer or multilayer passivating films. For chromate, the film is formed by iron oxidation (anodic... 

Bismuth is applied in ferrous and non-ferrous metallurgy as admixture for stainless steel, pig iron and non-ferrous alloys. Alloys of Bi-Pb-Sn-Cd system are known for having 50-70°C and even lower melting temperature. The world bismuth production is given in Table 4.4 [4.2, 4.3, 4.8]. 

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