Introduction About Alloys of Iron Video:
Iron castings are produced by a variety of molding methods and are available with a wide range of properties. Cast iron is a generic term that designates a family of metals.watch Alloys of Iron Video to learn more.
Alloys of Iron:
To achieve the best casting for a particular application at the lowest cost consistent with the component’s requirements, it is necessary to have an understanding of the six types of cast iron: • gray iron; • ductile iron; • compacted graphite iron (CGI); • malleable iron; • white iron; • alloyed iron. the typical composition ranges for common elements in five of the six generic types of cast iron.
Classification Of Iron:
The classification for alloyed irons has a wide range of base compositions with major additions of other elements, such as nickel, chromium, molybdenum or copper. The basic strength and hardness of all iron alloys is provided by the metallic structures containing graphite. The properties of the iron matrix can range from those of soft, low-carbon steel (18 ksi/124 MPa) to those of hardened, high-carbon steel (230 ksi/1,586 MPa). Because of their relatively high silicon content, cast irons inherently resist oxidation and corrosion by developing a tightly adhering oxide and subscale to repel further attack. Iron castings are used in applications where this resistance provides long life. Resistance to heat, oxidation and corrosion are appreciably enhanced with alloyed irons.
Properties of Iron:
Properties of the cast iron family can be adjusted over a wide range and enhanced by heat treatment. Annealing readily produces a matrix of soft machinable ferrite. In limited situations, this annealing can be accomplished at sub-critical temperatures. Heating above this critical temperature takes the carbon from the graphite and places it in the matrix. This engineered material can be through-hardened and tempered using conventional heat treating or surface hardening. These adjustments create the cast iron family. Gray iron—Flake graphite provides gray iron with unique properties (such as excellent machinability) at hardness levels that produce superior wear-resistant characteristics, the ability to resist galling and excellent vibration damping. Ductile iron—An unusual combination of properties is obtained in ductile iron because the graphite occurs as spheroids rather than as fl akes. The different grades are produced by controlling the matrix structure around the graphite either as-cast or by heat treatment. Only minor compositional differences (to promote the desired matrix microstructure) exist among the regular grades. Alloy additions may be made to assist in controlling the matrix structure as-cast or to provide response to heat treatment. The high-strength grades can be quenched and tempered to form a bainitelike matrix produced by austempering. Austempered ductile iron (ADI) provides twice the strength of conventional ductile iron at a given level of ductility. ADI can have strength in excess of 230 ksi (1,586 MPa); however, its modulus is 20% lower than steel with a comparable strength.
Useful for CBSE, ICSE, NCERT & International Students
Grade : 8
Subject : Chemistry
Lesson : Metals and Non Metals
Topic: Alloys of Iron Video
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