Active Standard ASTM A726 | Developed by Subcommittee: A06.02
Book of Standards Volume: 03.04
Historical (view previous versions of standard)
This specification covers the standard requirements for semi-processed cold-rolled magnetic lamination quality steels. These steels shall be made by the basic-oxygen or electric-furnace method and shall be processed by hot rolling, pickling, cold rolling, annealing, and temper rolling. Magnetic lamination steels shall have low-carbon contents and may have manganese, phosphorus, silicon, and aluminum additions to enhance punchability and to improve magnetic characteristics by increasing the electrical resistivity. There are no fixed chemical requirements for these steels only the requirement to meet the specified magnetic properties. These steels must be heat treated by the user to develop the specified magnetic properties. This specification covered steels with thicknesses of 0.0185 in. ( 0.47 mm), 0.022 in. (0.56 mm), 0.025 in. (0.64 mm), 0.028 in. (0.71 mm) and 0.031 in. (0.79 mm). For a given thickness there are three or more core loss types distinguished by maximum allowable core loss after a specified quality development anneal. Magnetic testing shall be done after the specified quality development anneal and shall use the Epstein test method. Magnetic testing shall be done at a test frequency of 60 Hz and a maximum flux density of 15 kG (1.5 T). Test methods to determine the magnetic and mechanical properties are listed. Other typical magnetic and physical properties are listed for reference.
This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. 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.
1.1 This specification covers cold-rolled carbon sheet steel used for magnetic applications. These products, commonly called “cold-rolled magnetic lamination steel” (CRML) are usually intended for applications in which the stamped laminations or assembled core structures for electrical equipment are annealed to develop the desired core loss and permeability characteristics.
1.2 By using appropriate lamination annealing practices, the user can optimize magnetic properties for the various types.
1.3 Non-guaranteed core-loss types, usually made to controlled chemical compositions, are available but are not covered by this specification.
1.4 Higher quality core-loss types are made to controlled chemical compositions and are usually given a critical reduction on a temper-mill to yield specified magnetic properties after a suitable lamination anneal. These products, typically called semiprocessed lamination steel, are classified by the ASTM Code Letter D in accordance with Practice A664.
1.5 The values stated in customary (cgs-emu and inch-pound) units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units which are provided for information only and are not considered standard.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
A340 Terminology of Symbols and Definitions Relating to Magnetic Testing
A343/A343M Test Method for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method and 25-cm Epstein Test Frame
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A664 Practice for Identification of Standard Electrical Steel Grades in ASTM Specifications
A700 Practices for Packaging, Marking, and Loading Methods for Steel Products for Shipment
E18 Test Methods for Rockwell Hardness of Metallic Materials
E140 Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, and Scleroscope Hardness