Cast iron high chromium

High-chromium white cast iron. High-chromium white cast iron has an abrasion resistance similar to martensitic white iron but with higher toughness, strength, and corrosion resistance. Its limitation is high cost. 

HIgh-chromium cast Irons. High-chromium cast irons are basically white cast irons alloyed with 12 to 30% Cr. Other alloying elements may also be added to improve resistance to specific environments. When chromium levels exceed 20%, high-chromium cast irons exhibit good... 

Carbon disulfide is normally stored and handled in mild steel equipment. Tanks and pipes are usually made from steel. Valves are typically cast-steel bodies with chrome steel trim. Lead is sometimes used, particularly for pressure reUef disks. Copper and copper alloys are attacked by carbon disulfide and must be avoided. Carbon disulfide Hquid and vapor become very corrosive to iron and steel at temperatures above about 250°C. High chromium stainless steels, glass, and ceramics maybe suitable at elevated temperatures. 

High-chromium cast irons and hardfacing alloys... 

For erosive wear. Rockwell or Brinell hardness is likely to show an inverse relation with carbon and low alloy steels. If they contain over about 0.55 percent carbon, they can be hardened to a high level. However, at the same or even at lower hardness, certain martensitic cast irons (HC 250 and Ni-Hard) can out perform carbon and low alloy steel considerably. For simplification, each of these alloys can be considered a mixture of hard carbide and hardened steel. The usual hardness tests tend to reflect chiefly the steel portion, indicating perhaps from 500 to 650 BHN. Even the Rockwell diamond cone indenter is too large to measure the hardness of the carbides a sharp diamond point with a light load must be used. The Vickers diamond pyramid indenter provides this, giving values around 1,100 for the iron carbide in Ni-Hard and 1,700 for the chromium carbide in HC 250. (These numbers have the same mathematical basis as the more common Brinell hardness numbers.) The microscopically revealed differences in carbide hardness accounts for the superior erosion resistance of these cast irons versus the hardened steels. 

There is no clear demarcation between high-chromium steels and high-chromium cast irons other than the fact that components are fabricated from the steels, and cast in the irons. In practice, however, the irons are usually found to have carbon contents of between 0-6 and 3%, while most of the steels contain less than 0-3% carbon. 

Silicon may be present in high-chromium irons in amounts varying between 0-5 and 2-5%. Its effect is to increase fluidity in the foundry and improve the surface quality of castings. Further effects are to refine the eutectic carbides in the iron, to produce a more uniform structure and to raise the temperature at which the matrix transforms from ferrite to austenite with consequent dimensional changes. Additions above 2-5% have an embrittling effect. 

Broadly speaking, the high-chromium irons are hard but not completely unmachinable. Typical properties for irons of the compositions described above in the as-cast state are ... 

Ferrous materials steel, cast iron, iron, stainless steel, high-silicon iron, high-silicon molybdenum iron, high-silicon chromium iron, magnetite, ferrite. 

Medium and high-carbon steels Cast irons Chromium 850-980 (Halide) 1. Gaseous 2. Semi- gaseous 3. Pack 4-40 /im Matrix plus chromium carbides 60-80% Cr 1 500-1 800 HV Heat treatment acceptable ... 

Most cast irons, except those fully decarburised during malleabilising, give coatings of the chromium carbide type. In view of the great variations in composition of cast irons, reproducibility of results can be achieved only by careful control of specification. High phosphorus and sulphur contents are detrimental to the formation of non-porous coatings. 

FERROCHROMIL M. An alloy, composed principally of iron and chromium, used as a means of adding chromium to steels How. medium, and high-carbon I and cast iron. Available in several classifications and grades, generally containing between 60 to 705( chromium, in crushed sizes and lumps up to 75 pounds dial readily dissolve in molten steel. 

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