Ferrite former

The solidification behaviour is governed by the proportions of austenite- and ferrite-forming elements present. The first group comprises carbon, nitrogen, nickel, manganese, copper and cobalt. (At high concentrations manganese has been reported to be a ferrite former, [66].)... 

The most important ferrite formers are chromium, silicon, molybdenum, niobium, titanium and aluminium. The ferritic and martensitic grades have already been described in chapter 3. The alloys of the present section, belonging to the ferritic-austenitic and the austenitic groups were chosen to give examples of the different solidification paths. The alloys are listed in table 4.2 in order of increasing tendency to solidify as austenite ... 

It has been established that certain elements, specifically chromium, mol)d)denum, and silicon, are ferrite formers. Aluminmn and niobium may also act as ferrite formers depending upon the alloy system. Other elements, such as nickel, manganese, carbon, and nitrogen, tend to promote the formation of austenite. 

The two main varieties of malleable iron arc ferritic and pcarlitic. the former more machinable and more ductile the latter stronger and harder. Carbon in malleable iron ranges between 2.30 and 2.65%. Ranges of other constituents are manganese, 0.30 to 0.40% silicon, 1.00 to 1.50% sulfur, 0.07 to 0.15% and phosphorus, 0.05 to 0.12%. 

Iron dioxide is not known in the free state, but it can exist in combination, as witness such ferrites as barium ferrite, BaFc03. The dioxides of ruthenium, RuOa, and osmium, 0s02, arc known. The former is isomorphous with cassiterite, Sn02, and rutile, TiOa and combines with bases to form ruthenites, for example, barium ruthenite, BaRuOg. 

Former S-dendrites, (transformed to y by the pe-ritectic reaction), and interdendritic ferrite (8). 

Figures 6 — 9 Note that the residual ferrite only appears in the former S-dendrites.

Figures 2—3 Former 8-dendrites, y-dendrites, dendritic and interdendritic ferrite, (compare figures 8 — 9).

Former 6-dendrites, y-dendrites and interdendri-tic ferrite, (compare figurell). 

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