ASTM A Standard Specification for Gray Iron Castings for Pressure- Containing Parts for Temperatures up to Degrees F. Find the most up-to-date version of ASTM A at Engineering Purchase your copy of ASTM A/AM – 01() as a PDF download or hard copy directly from the official BSI Shop. All BSI British.
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ASTM A278/A278M – 01(2015)
Excessive vibration causes inaccuracies in precision machinery and excessive wear on gear teeth and bearings. The graphite takes on the shape of a three-dimensional flake. The individual design of a casting the molding process, the way the molten metal is introduced into the cavity and the pouring temperature determines the rate of cooling in the various parts of an iron casting.
Another factor affecting graphitization is the solidification rate; the slower the rate, the greater the time for the carbon to diffuse and accumulate into graphite.
Retrieved from ” https: ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date. In two dimensions, as a polished surface, the graphite flakes appear as fine lines. Higher strength gray irons, up to class 40, have lower carbon equivalents and a pearlite matrix. It also has good galling and wear resistance because the graphite flakes self lubricate.
However, ductile iron is replacing malleable iron in many applications because the engineering properties of ductile iron castings are almost identical to that of malleable iron, and ductile iron does not require extensive heat treatment to precipitate graphite.
To efficiently machine cast irons, the appropriate tool material of the correct grade and shape must be selected. Abrasion Resistant Irons excel in applications with a high degree of axtm and low impact.
Grey 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.
It is named after the gray color of the fracture it forms, qstm is due to the presence of graphite. Login to see your most recently viewed materials here. Ferritic malleable iron is produced to a lower strength range than pearlitic malleable iron but with higher ductility. Free Trade Publications, Click Here!
ADI Properties Austempering of ductile iron castings awtm higher temperatures produces ADI with lower strength and hardness, as well as higher ductility and toughness. Gray Iron is commonly referred to as Cast Iron. Questions or comments about MatWeb? Click here to view all the property values for this datasheet as they were originally entered into MatWeb. Characteristic astn of Gray Iron are excellent machinability, good wear resistance, high vibration absorption, and good fluidity.
Austempered ductile iron ADI provides twice the strength of conventional ductile iron at a given level of ductility. Grey Iron Compressor Body.
Although some production iron foundry facilities have established guidelines for their own capability in dimensional control, these controls are typically established through engineering based on the requirements of the application and the needs of the end user. The damping capacity of gray iron is about times higher than steel. New tool materials for economical machining of iron castings are in a continual state of improvement and development. Referenced Documents purchase a27 The documents listed below are referenced within the subject standard but are not provided as part of the standard.
To achieve a fully ferritic matrix the alloy must be annealed. Class 20 has a high carbon equivalent and a ferrite matrix. Chemical analysis shall be performed on each class of castings and shall meet the maximum requirement for carbon, phosphorus and sulfur.
A Class ASTM :: Total Materia
It is used for housings where the stiffness of the component is more important than its tensile strength, such as internal combustion engine cylinder blockspump housings, valve bodies, ast boxes, and decorative castings. The three numbers in the Ductile Iron designation represent the physical properties of the iron.
In other projects Wikimedia Commons. Gray ironor grey cast ironis a type of cast iron that has a graphitic microstructure. It can be a2788 in a wide range of casting sizes and section thickness; however, thinner sections may require annealing to obtain high ductility. The different grades of ductile iron castings are produced by controlling the matrix structure around the graphite either as cast or by heat treatment.
The majority of carbon is in the form of iron carbides making it very hard, brittle and in most cases unmachinable. Ductile Iron has steel like mechanical properties with the castability, machinability, and x278 resistance of Gray Iron.
In thin sections, the material can be hard and difficult to machine. Strength and hardness are sensitive to section thickness in gray iron castings. Gray iron is a common engineering alloy because of its relatively low cost and good qstmwhich results from z278 graphite lubricating the cut and breaking up the chips. Property Comparisons for Gray Iron Classes. Subscribe to Premium Services Searches: Ductile Iron is commonly known as Nodular Iron.
Alloy additions may be needed to obtain atm higher-strength grades in heavy sections. The silicon promotes good corrosion resistance and increased fluidity when casting. Ductile Iron Pillow Block. A typical chemical composition to obtain a graphitic microstructure is 2. This specification covers gray iron for castings suitable for pressure-containing parts at elevated temperatures.