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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A Class 30 ASTM :: Total Materia
The class then is identified as a grade. Combining values from the two systems may result in non-conformance with the standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. In thin sections, the material can be hard and difficult to machine.
The iron is cast as a white iron of a suitable chemical composition to respond to the malleabilizing heat treatment. The different metals within this family xstm separated further into the following classifications:.
Strength and hardness are sensitive to section thickness in gray iron castings.
These grades are a measure of the tensile strength-to- Brinell hardness ratio. Lower Classes of Gray Iron provide better machinability with higher classes offering strength and wear resistance. Coated carbides, particularly those with aluminum oxide exteriors, are effective in production machining applications. Tension test shall be performed on each lot and materials shall conform to the tensile requirements specified. The two specifications approach the task from different standpoints, but the concept essentially remains the same.
Only minor compositional differences to promote the desired matrix microstructure exist among the regular grades.
The graphite takes on the shape of a three-dimensional flake. Castings to be used at a particular temperature range shall undergo heat treatment and cooling. Separately cast test bars having the required dimensions shall be poured from the same lot as the castings represented.
ASTM A278/A278M – 01(2015)
Ductile Iron Pillow Block. Ductile Iron has steel like mechanical properties with the castability, machinability, and corrosion resistance of Gray Iron. Ductile Iron Link Pin. Class 20 has a high carbon equivalent and a ferrite matrix. Types of Specifications When mechanical properties are important, the most common procedure to asfm gray or ductile iron castings is to use a standard test bar poured separately with the specified lot of general engineered castings.
These specifications give the minimum tensile and impact levels along with typical Brinell hardness values Table 5. The contents, results, and technical data from this site may not be reproduced either electronically, photographically or substantively without permission from MatWeb, LLC. To efficiently machine cast irons, the appropriate tool material of the correct grade and qstm must be selected. Grey Iron Compressor Head.
To achieve a fully ferritic matrix the alloy must be annealed. Login to see your most recently viewed materials here. There is an insignificant amount of graphite present in Abrasion Resistant Irons. Austempering of ductile iron castings at higher temperatures produces ADI with lower strength and hardness, as well as higher ductility and toughness. 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.
A typical chemical composition to obtain a graphitic microstructure is 2. Or if you don’t have an account with us yet, then click here to register. Cast iron is a generic term that designates a family of metals. It can be cast atm a wide range of casting sizes and section thickness; however, thinner sections may require annealing to obtain high ductility.
Grey iron also has very good damping capacity and hence it is often used as the base for machine tool mountings. Austempered ductile iron ADI provides twice the strength of conventional ductile iron at a given level of ductility. The silicon promotes good corrosion resistance and increased fluidity when casting.
Free Trade Publications, Click Here! Excessive vibration causes inaccuracies in precision machinery and excessive wear on gear teeth and bearings.
The acceptance of the castings is based on characteristics that a metalcasting facility or independent third party can evaluate and control during production. In some applications, the finished component is tested in the manner in which it will be used. Ductile iron has the ability to be used as-cast and atm heat treatments or other further refining.
In two dimensions, as a polished surface, the graphite flakes appear as fine lines. The majority of carbon is in the form of iron carbides making it very hard, brittle and asgm most cases unmachinable.
Iron Castings Properties – Foundry Source
This specification covers gray iron for castings suitable for pressure-containing parts at elevated temperatures. 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. For example, the number in a Class 30 gray iron refers to the minimum tensile strength in ksi.
The damping capacity of gray iron is about times higher than steel.