It exhibits good pressure tightness under high stress and can be welded and brazed. The American National Standard Specifications for Gray Iron Castings—ANSI/ASTM A48-76 groups the castings into two categories. Different varieties of cast iron are used in the construction of structures and machinery. Castings in Classes 40B, 40C, 45B, 45C, 50B, 50C, 60B, and 60C are usually more difficult to machine, have lower damping capacity, higher modulus of elasticity, and are more difficult to manufacture. Copyright © Science Struck & Buzzle.com, Inc.
Carbon steel castings may be designated as low-carbon, medium-carbon, and high-carbon. Corrosion resistance of cast iron is improved via the addition of minor elements such as silicon, nickel, chromium, molybdenum and copper [3]. Stay up to date on industry news and trends, product announcements and the latest innovations. Cast iron has a wide range of applications including its usage in machinery, cookware, pipes, car parts such as cylinder heads, blocks, gearbox cases, etc. White cast iron gets its colouring from perlite mixed into metal and carbon only in the form of carbide in the metal, which prevents industry from melting and moulding the white cast iron as it would other forms of iron. Thus, Grade 60–40–18 has a minimum tensile strength of 60,000 psi, a minimum 0.2 percent yield strength of 40,000 psi, and minimum elongation in 2 inches of 18 percent. We also use third-party cookies that help us analyze and understand how you use this website. But opting out of some of these cookies may have an effect on your browsing experience. Cast iron has lot of engineering properties so, that it can be used in many ways like for sanitary fittings, rail chairs, casting molds etc. Malleable iron can be shaped into various sizes and thicknesses without breaking. White cast iron gets its colouring from perlite mixed into metal and carbon only in the form of carbide in the metal, which prevents industry from melting and moulding the white cast iron as it would other forms of iron. There are many advantages of using white cast iron. google_ad_height = 250; The term cast iron refers to those iron carbon silicon alloys which contain 1.8 % – 4 carbon (C) and usually 0.5 % – 3 % silicon (Si). It is in silver color. According to "Cast Irons," white cast iron leavings make a cost-effective alternative to stainless steel for high heat applications. Deep hardening. The matrix is ferrite. Following are the properties of cast iron: 1. Following are the types of cast iron used as a building material in construction and their uses: As the name suggests, it is grey in color. Nominal Chemical Composition and Mechanical Propertiesof Corrosion-Resistant Steel Castings ASTM A743-81a. White cast iron contains 1.8 % -3.6 % C, 0.5 % -1.9 % Si and 1 % – 2 % manganese (Mn). It melts at temperatures of about 2100-2190ºF, and has a crystalline or a granular fracture. It can be produced in selected areas of a casting—such as on the periphery of a cam—by causing localized rapid solidification of the iron. Cast iron may not be useful for forging work due to lack o… In the as-cast condition, austenitic manganese steel is quite brittle. Ductile cast iron contains 3.2 wt.% – 3.6 wt.% carbon, 2.2 wt.% – 2.8 wt.% silicon and 0.1 wt.% – 0.2 wt.% manganese, as well as smaller amounts of magnesium, phosphorus, sulfur and copper. When nearly all of the carbon in a casting is in the combined or cementite form, it is known as white cast iron. Deep hardening. The high Cr white cast irons (class III of ASTM A 532) represent the oldest grade of high Cr white cast irons, with the earliest patents dating back to 1917. Through the ispatguru.com website I share my knowledge and experience gained through my association with the steel industry for over 54 years. as described below. The lower portion of Table 1 gives the engineering grades of low-alloy cast steels grouped according to tensile strengths and gives properties normally expected in the production of steel castings. White cast irons are used in abrasion-resistant parts where it’s brittleness is of minimum concern such as shell liners, slurry pumps, ball mills, lifter bars, extrusion nozzles, cement mixers, pipe fittings, flanges, crushers and pump impellers. Cast iron, an alloy of iron that contains 2 to 4 per cent carbon, along with varying amounts of silicon and manganese and traces of impurities such as sulfur and phosphorus. This type of white cast iron has higher toughness because of less carbide and is used in those areas where repeated impact is there. A popular grade of white iron is high chrome white irons, ASTM A532. The melting point is about 1250 ºC. Cast iron can be classified into grey cast iron, white cast iron, malleable cast iron and ductile cast iron, depending on its composition. These general purpose white cast irons, also called 25 % Cr and 28 % Cr cast irons, contain 23 % to 28 % Cr with up to 1.5 % Mo. A low percentage of silicon allows carbon to remain in solution forming iron carbide and the production of white cast iron. Country These cast irons are limited in application because of the lack of impact resistance and the difficulty in maintaining the structure in thicker sections. Its composition normally falls within the following ranges: carbon, 1.00 to 1.40 percent; manganese, 10.00 to 14.00 percent; silicon, 0.30 to 1.00 percent; sulfur, 0.06 percent max. High-strength iron castings produced by the Meehanite-controlled process may have various combinations of physical properties to meet different requirements. a Quench and temper heat treatments may also be employed for these classes. Copyright© 2020 Thomas Publishing Company. Depending on the silicon content of the cast iron, it is classified as either white cast iron or grey cast iron and may be treated further under particular temperatures to produce malleable or ductile cast iron. White cast iron contains 1.8 % -3.6 % C, 0.5 % -1.9 % Si and 1 % – 2 % manganese (Mn). Some forms are made rigid to resist deformation while others will undergo considerable deformation before breaking. Ni hard white cast irons are very cost effective materials for use in crushing and grinding. High-alloy white cast irons normally have austenite matrix in as-cast state, but is changed to hard martensite by heat-treatment. Compared to the lower alloy Ni-Cr white cast irons, the eutectic carbides are harder and can be heat treated to achieve castings of higher hardness. The presence of carbon in this form, as opposed to graphite, is the result of a lower silicon content compared to grey cast iron. Fully annealed high-carbon steel castings exhibit tensile strengths of from 95,000 to 125,000 pounds per square inch (655-125 MPa). Become VIP Member, Do you need to remove the ads? Medium-carbon steel castings have a carbon content of from 0.20 to 0.50 percent. There are four types of Ni- Cr white cast irons. ksi = kips per square inch = 1000s of pounds per square inch; MPa = megapascals. Cloud Computing in Construction: Are we Availing all its Benefits? © 2009-2020 The Constructor. Chilled cast iron consists two layers of which one layer has white cast iron properties and other one has grey cast iron properties. This method is used in SAE Specification J434C for automotive castings and similar applications. Their tensile strengths range from 65,000 to 105,000 pounds per square inch (448-724 MPa) depending, in part, upon heat treatment. It has very good engineering properties than malleable cast iron. Malleable cast irons are formed via a slow annealing heat treatment of white cast iron. It cannot be useful for forging work because of lack of plasticity. Table 3. Cast Iron as a Building Material- Manufacturing, Types, Properties and Applications, Quality Control and Applications of Foam Concrete in Construction Works, Types of Bitumen Mixes for Pavement Construction and their Applications, Tips to Avoid Reinforcement and Embedment Congestion in Concrete Members. Their tensile strengths (annealed condition) range from 40,000 to 70,000 pounds per square inch (276-483 MPa). Instead the C, which is in solution in the melt, forms iron carbide. The excess carbon is in the form of graphite flakes, which impart to the material the dark-colored fracture that gives it its name. Thomas Regional® are part of Thomasnet.com. Alloy cast irons are used extensively for such parts as automotive cylinders, pistons, piston rings, crankcases, and brake drums; for certain machine tool castings; for certain types of dies; for parts of crushing and grinding machinery; and for applications where the casting must resist scaling at high temperatures.