Active Standard ASTM A646 / A646M | Developed by Subcommittee: A01.06
Book of Standards Volume: 01.05
Historical (view previous versions of standard)
This specification deals with the standard requirements for premium quality alloy steel semifinished rolled or forged blooms and billets for reforging into aircraft and aerospace critical parts such as landing-gear forgings. Covered here are three basic classifications of steel, namely: Class I, steel manufactured by vacuum-induction melting or consumable-electrode vacuum melting process; Class II, air-melted steel manufactured by electric-furnace vacuum degassing process; Class III, air-melted steel manufactured by electric-furnace ladle refining and vacuum degassing processes. Steel materials shall be heat-treated and hot-worked by either hot rolling or forging. Alloy steels shall be examined by heat and product analyses and hardenability tests, and shall conform to chemical composition and maximum annealed Brinell hardness requirements. Quality evaluation tests, such as macrotech, microcleanliness, and nondestructive ultrasonic (both immersion and contact examination) inspection, shall be performed as well.
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 premium quality alloy steel semifinished rolled or forged blooms and billets for reforging into critical parts such as aircraft landing-gear forgings.
1.2 Blooms and billets, hereinafter referred to as blooms, are semifinished steel products, hot rolled or forged to approximate cross-sectional dimensions. Blooms may be square, round, hexagonal, octagonal, or rectangular in section. For the purposes of this specification, minimum bloom section size will be 16 in.2 [103 cm2].
1.3 This specification covers two basic classifications of steel:
1.3.1 Class I—Vacuum-induction melted or consumable-electrode vacuum melted, or other suitable processes which will satisfy the quality requirements of this specification.
1.3.2 Class II—Air-melted vacuum degassed.
1.3.3 Class III—Air melted electric furnace ladle refined and vacuum degassed
1.4 The values stated in either inch-pound or SI (metric) units are to be regarded separately as standards. Within the text and tables, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.
1.5 Unless the order specifies the applicable “M” specification the material shall be furnished to the inch-pound units.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
A255 Test Methods for Determining Hardenability of Steel
A388/A388M Practice for Ultrasonic Examination of Steel Forgings
A604 Test Method for Macroetch Testing of Consumable Electrode Remelted Steel Bars and Billets
A788/A788M Specification for Steel Forgings, General Requirements
E45 Test Methods for Determining the Inclusion Content of Steel
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam Contact Testing
E127 Practice for Fabricating and Checking Aluminum Alloy Ultrasonic Standard Reference Blocks
E214 Practice for Immersed Ultrasonic Testing by the Reflection Method Using Pulsed Longitudinal Waves
E381 Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings
AMS StandardsAMS 2304 Steel Cleanliness, Special Aircraft-Quality
ICS Number Code 49.025.10 (Steels)