ASTM A848
This specification covers the standard requirements for wrought low-carbon iron having a carbon content of 0.015% or less with the remainder of the analysis being substantially iron. Two alloy types are covered: Type 1 is a low-phosphorus grade and Type 2 contains a phosphorus addition to improve machinability. The alloy specimens shall conform to the required chemical compositions of carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel, vanadium, titanium, aluminum and iron. The alloys shall be produced in a wide variety of forms and conditions namely: forging billet; hot-rolled product; cold-finished bars; strip; wire; and relay condition. The alloy materials shall undergo heat treatment. Magnetic testing shall also be performed wherein the alloys shall conform to the required values of the coercive field strength.
1.1 This specification covers the requirements for wrought low-carbon iron typically having a carbon content of 0.015\u2009% or less with the remainder of the chemical composition being substantially iron.
1.1.1 Two alloy types are covered: Type 1 is a low-phosphorous grade and Type 2 contains a phosphorous addition to improve machinability.
1.2 This specification also covers alloys supplied by a producer or converter in the form and condition suitable for fabrication into parts which will be subsequently heat treated to create the desired magnetic characteristics. It covers alloys supplied in the form of forging billets, hot-rolled products, and cold-finished bar, wire, and strip.
1.3 This specification does not cover iron powders capable of being processed into magnetic components. Please refer to the following ASTM Standards for information regarding powdered metal materials and magnetic components: Specifications A811, A839, and A904.
1.4 This specification does not cover flat-rolled, low-carbon electrical steels. Please refer to Specification A726 for information regarding these materials.<\/p>\n\n\n\n
Soft Magnetic Core Iron is a low carbon magnetic iron produced using vacuum induction melting and vacuum arc re-melting processes.
Other elements commonly found in low carbon irons are held as low as possible to ensure good DC magnetic properties. The double melting technique keeps the distribution of non-metallic inclusions to a minimum length and frequency so that thin wall sections will not contain leaks due to internal discontinuities.
Applications
Used in components where vacuum integrity is needed, such as power tubes and microwave devices
Relays, solenoids, magnetic pole pieces for scientific instruments
This product has an Iron content of 99.85% Min, without the addition of alloy elements. All natural impurities have been largely removed.
Pure iron undergoes pacification after melting by means of vacuum degassing following solidification. It therefore has a homogenous composition with regard to distribution of the accompanying elements, a very low oxygen content, and due to the low Carbon content, the micro structure consists of pure ferrite.
This material supports excellent magnetic properties and resistance against corrosion and oxidation. It has good cold forming capabilities and is well suited to welding.
Applications
Aviation construction
Nuclear technology
Magnet production
Automotive construction
Power station construction
Gaskets in the chemical and petrochemical industries
Magnetic shielding
Welding rods and fuse wire
An anti-corrosion anode<\/p>\n\n\n\n
SPECIALTY PRODUCTS
Specialty Products:
Ultra-low Carbon Magnetic Iron Strip & Sheet per ASTM A-848-01
Ultra-low Carbon Magnetic Iron Precision Cold Rolled Foil
Ultra-low Carbon Magnetic Iron Hot-Rolled Pickled and Oiled Sheet
Magnetic Core Iron Cold Drawn Rod and Bar per ASTM A-848-01
Open Die Forgings for Magnetic Applications
Hot Rolled Bars per ASTM A-848-01<\/p>\n\n\n\n
Magnetic materials are broadly classified into two groups with either hard or soft magnetic characteristics. Soft magnetic behavior is essential in any application involving changing electromagnetic induction such as solenoids, relays, motors, generators, transformers, and magnetic shielding. This Article provides a description on ferromagnetic properties, the effect of impurities, alloying additions, heat treatment, residual stress, and grain size on magnetic properties. It also describes the alloy classification and magnetic testing methods of soft magnetic materials, which include high-purity iron, low-carbon steels, silicon steels, iron-aluminum alloys, nickel-iron alloys, iron-cobalt alloys, ferrites, and stainless steels. The Article discusses the corrosion resistance of soft magnetic materials, and provides information on selection of alloys for power generation applications, including motors, generators and transformers. It concludes with a short note on design and fabrication of magnetic cores.<\/p>\n\n\n\n
ASTM A848Type1 ASTM A848 Mechanical
The main mechanical properties are elasticity, plasticity, stiffness, aging sensitivity, strength, hardness, impact toughness, fatigue strength and fracture toughness.
Elasticity: Metal material deforms when it is subjected to external force. When the external force is removed, it can restore its original shape.
Plasticity: The ability of ASTM A848Type1 ASTM A848 to produce permanent deformation without causing damage under external forces.
Stiffness: The ability of ASTM A848Type1 ASTM A848 to resist elastic deformation under stress.
Strength: The ability of ASTM A848Type1 ASTM A848 to resist deformation and fracture under external forces.
Hardness: The ability of ASTM A848Type1 ASTM A848 to resist the pressure of a harder object into it.
Impact toughness: The ability of ASTM A848Type1 ASTM A848 to resist fracture under impact loading.
Fatigue strength: The maximum stress that does not cause fracture when ASTM A848Type1 ASTM A848 is subjected to numerous repeated or alternating loads.
Fracture toughness: a performance index used to reflect ASTM A848Type1 ASTM A848 is ability to resist crack instability and expansion<\/p>\n\n\n\n
Scope Description:
Electric propulsion for space applications has demonstrated tremendous benefit to a variety of NASA, military, and commercial missions. Critical NASA electric propulsion needs have been identified in the scope areas detailed below. Proposals outside the described scope shall not be considered. Proposers are expected to show an understanding of the current state of the art (SOA) and quantitatively (not just qualitatively) describe anticipated improvements over relevant SOA materials, processes, and technologies that substantiate NASA investment.
To shape the magnetic fields needed for operations, Hall-effect thrusters utilize a magnetic circuit that also forms the thruster structure. The magnetic circuit components direct magnetic flux (typically produced by electromagnetic coils) and may experience operational temperatures in excess of 500 \u00b0C due to coil self-heating and the close proximity of plasma-wetted surfaces. Both low-carbon magnetic iron and cobalt-iron (Co-Fe) soft ferromagnetic alloys have been traditionally used in the role; low-carbon magnetic iron is typically cheaper with larger billet size availability, whereas Co-Fe soft ferromagnetic alloys are attractive due to high magnetic saturation and Curie temperature properties. As Hall-effect thrusters become larger to support future high-power applications, thruster components also experience and must survive increased inertial launch loads. To address this issue, prospective magnetic circuit materials are desired with improved structural strength compared to SOA options while retaining comparable or better magnetic and thermal properties. Prospective materials capable of being produced in machinable, large-diameter (i.e., >400 mm) solid billets\u2014or that can be additively manufactured to achieve comparable sizes\u2014are of particular interest. This solicitation seeks such prospective magnetic circuit materials suitable for Hall-effect thruster applications with the following properties:
Mechanical: Meets or exceeds yield stress properties in Table X2.4 of ASTM Standard A801-14.
Magnetic: Meets or exceeds properties in Appendix X1 of ASTM Standard A848-17.
Thermal: Meets or exceeds Curie temperature of 770 \u00b0C.<\/p>\n\n\n\n
Method and apparatus for radial elecromagnetic power arrays
Abstract
Multiple arrays of linear motors and generators are combined in a radial configuration to provide high mechanical efficiency to deliver power in a single plane of motion to a common crankshaft. Magnet core assemblies for the motors and generators use powerful rare earth magnets positioned within an outer flux containment shell comprising a highly-magnetically-permeable ferrous-alloy to provide high power density. The motor magnet stack is attached directly to a link rod that connects to the crankshaft. Pulsed power is provided to electromagnetic coils by microcomputer control, and coil energy is recovered at the ends of the linear stroke. A controller energizes the coils in certain combinations of coil location and polarity in order to produce bi-directional mechanical motion. Energy that is released when coils are switched off is harvested as voltage pulses returned to standby batteries or capacitors, or the electrochemical cells.<\/p>\n\n\n\n
DETAILED DESCRIPTION – Linear Actuators
As described below, improved linear actuators may be used in motors, generators, prime movers, and systems. ferrous properties and flux containment
A magnetic circuit behaves in a similar fashion to an ordinary electrical circuit in that magnetic elements can have “magnetic conductivity” or magnetic resistance, and there are limits to how much magnetic current a structure can carry before saturation. When Weodymium magnets are used in a device, it’s not uncommon to experience magnet induced flux densities near 1.5 Tesla. Most common materials like ferrites and carbon steels saturate at less than a third of this flux density- between 0.2 to 0.5 Tesla. In applicant’s experience, properly annealed ASTM A848 metal provides the highest commercially available flux density. As improved materials become available, those materials may be used for containment structures in linear elements.
Specifying ASTM A848 metal and invoking an appropriate annealing process gives the linear elements significant magnetic performance enhancements over other materials. The results are increased shaft power and decreased waste heat. Only a few suppliers provide the preferred raw metal for high- performance magnetics. These metals chemically meet or exceed ASTM A848 raw alloy standards. By “raw” it is meant that it is the user’s responsibility to anneal the raw materials so as to enhance and maximize the raw metal’s latent magnetic properties.
Performance is largely a function of the time-temperature history of the metal and its chemical composition. For example, annealing special ferrous metals, when properly performed, will maximize the magnetic permeability and saturation flux density of the outer shell flux containment canisters in linear elements. Optimum magnetic flux path performance is critical to achieve the aforementioned performance enhancements – in short, a far superior embodiment of magnetic principles over
conventional approaches is ensured by selecting the correct material and annealing it correctly. Rather than shun the use of ferrous metal in a reciprocating magnetic motor that uses Neodymium magnets, applicants embrace the use of ferrous material because the quality of ferrous material and the location of components circumvent the problems encountered in conventional systems when the designers attempt to combine Neodymium magnets in the near presence of ferrous structures.
Example annealing process
In an example annealing process, the sample is placed in a stainless steel bag such as provided by SenPak to eliminate oxygen exposure to the sample. The sealed bag placed in a muffle furnace or other suitable annealing furnace of 0- 1000 deg Centigrade range or greater. An annealing is performed by ramping the oven temperature from ambient to 845 degrees C at a ramp rate not to exceed 2 degrees C\/minute; the oven temperature is held at 845 deg C for 2 hours; the oven temperature is ramped from 845 degrees C to 500 degrees C at a ramp rate not to exceed 1 degrees C\/minute; and the oven temperature is ramped from 500 degrees C to ambient at a ramp rate not to exceed 2.5 degrees C\/minute.
Shell fabrication methods
The flux canisters shown in the figures above are solid, metal cylinders made of ASTM A848 magnetic metal stock which provided approximately a 1 OX improvement over the floral wire wound shell. The parts were deliberately over sized in terms of wall thickness so as to avoid magnetic saturation of the parts during system operation. Air gaps in a magnetic assembly cause loss in magnetic flux capability and can lead to flux saturation. Air gaps, such as between th&magnet stacks and motor shell liners, could be decreased via tighter tolerances that may be obtainable with a lamination process and more precise machining
Ferrous magnetic flux structures such as flux containment shells, end caps, spacer washers, etc., can be fabricated from multiple layers of thin material. A shell made of laminations where the individual lamination layer is coated with a non-electrically conductive material such as thin plastic or shellac stops eddy currents from forming and thus reduces or eliminates magnetically- induced heating in the shell.
Thin sheets of 0.025 inch ASTM A848 metal are available for use in making laminations. In this example, the containment shell for a motor would require about 330 layers of magnetic
metal, possibly coated with shellac, and bolted together.
One type of lamination is a washer embedded in a NIB magnet stack. Washers or spacers help to reduce the magnetic NIB material required to make a magnet stack. For example, just one or two NIB magnets may be used, with the rest of the magnet stack using thin laminations of
properly-annealed ASTM A848.<\/p>\n\n\n\n
Standard Specification for Low-Carbon Magnetic Iron<\/p>\n\n\n\n
ROLEX METAL DISTRIBUTORS ASTM A848This specification covers the standard requirements for wrought low-carbon iron having a carbon content of 0.015% or less with the remainder of the analysis being substantially iron. Two alloy types are covered: Type 1 is a low-phosphorus grade and Type 2 contains a phosphorus addition to improve machinability. The alloy specimens shall conform to […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-702","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/rolexiron.com\/index.php\/wp-json\/wp\/v2\/pages\/702","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rolexiron.com\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/rolexiron.com\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/rolexiron.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/rolexiron.com\/index.php\/wp-json\/wp\/v2\/comments?post=702"}],"version-history":[{"count":1,"href":"https:\/\/rolexiron.com\/index.php\/wp-json\/wp\/v2\/pages\/702\/revisions"}],"predecessor-version":[{"id":703,"href":"https:\/\/rolexiron.com\/index.php\/wp-json\/wp\/v2\/pages\/702\/revisions\/703"}],"wp:attachment":[{"href":"https:\/\/rolexiron.com\/index.php\/wp-json\/wp\/v2\/media?parent=702"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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