ASTM B661-06
(Practice)Standard Practice for Heat Treatment of Magnesium Alloys
Standard Practice for Heat Treatment of Magnesium Alloys
ABSTRACT
This practice is intended as an aid for establishing a suitable procedure for the heat treatment of magnesium alloys to achieve the proper physical and mechanical properties. Air chamber furnaces that may be either electrically heated, or oil- or gas-fired, are usually used for the heat treatment process. Each furnace must be gas tight, have suitable equipment for protective atmosphere, be equipped with a high-velocity fan or any other comparable means for circulating the atmosphere, and designed so that no direct radiation from the heating elements or impingement of the flame on the magnesium. It is also important that the furnace be calibrated before it is used initially and after any change in the furnace. Likewise, temperature-measurement systems should be regularly checked for accuracy.
SCOPE
1.1 This practice is intended as an aid in establishing a suitable procedure for the heat treatment of magnesium alloys to assure proper physical and mechanical properties.
1.2 Times and temperatures are typical for various forms, sizes, and manufacturing methods and may not exactly describe the optimum heat treatment for a specific item. Consequently, it is not intended that this practice be used as a substitute for a detailed production process or procedure.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: B661 − 06
StandardPractice for
1
Heat Treatment of Magnesium Alloys
This standard is issued under the fixed designation B661; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope* tible to aging, there is a unique range of time-temperature
combinations to which it will respond.
1.1 This practice is intended as an aid in establishing a
suitable procedure for the heat treatment of magnesium alloys 3.1.2 heat treatment—Acombination of heating and cooling
to assure proper physical and mechanical properties. operationsappliedtoametaloralloyinthesolidstatetoobtain
desired conditions of properties. Heating for the sole purpose
1.2 Times and temperatures are typical for various forms,
of hot working is excluded from the meaning of this definition.
sizes, and manufacturing methods and may not exactly de-
scribe the optimum heat treatment for a specific item. 3.1.3 solution heat treatment—A treatment in which an
Consequently, it is not intended that this practice be used as a alloy is heated to a suitable temperature and held at this
substitute for a detailed production process or procedure. temperature for a sufficient length of time to allow a desired
constituent to enter into solid solution, followed by rapid
1.3 This standard does not purport to address all of the
cooling to hold the constituent in solution. The material is then
safety concerns, if any, associated with its use. It is the
in a supersaturated, unstable state, and may subsequently
responsibility of the user of this standard to establish appro-
exhibit Age Hardening.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
3.1.4 quenching—Rapid cooling. When applicable, the fol-
lowing more specific terms should be used: still air quenching,
2. Referenced Documents
forced air quenching, hot water/polymer quenching.
2
2.1 ASTM Standards:
3.1.5 T4—Solution heat-treated and naturally aged to a
B557 Test Methods for Tension Testing Wrought and Cast
substantially stable condition.
Aluminum- and Magnesium-Alloy Products
3.1.6 T5—Artificially aged only:Applied to products which
E21 TestMethodsforElevatedTemperatureTensionTestsof
are artificially aged after an elevated-temperature rapid-cool
Metallic Materials
fabrication process, such as casting or extrusion, to improve
E527 Practice for Numbering Metals and Alloys in the
mechanical properties or dimensional stability, or both.
Unified Numbering System (UNS)
3.1.7 T6—Solution heat-treated and then artificially aged:
Applies to products which are not cold worked after solution
3. Terminology
heat-treatment.
3.1 Definitions of Terms Specific to This Standard:
3.1.1 aging—Describes a time-temperature-dependent
4. Apparatus
change in the properties of certain alloys. Except for strain
4.1 Furnaces used for the heat treatment of magnesium are
aging and age softening, it is the result of precipitation from a
usually of the air chamber type and may be electrically heated
solid solution of one or more compounds whose solubility
or oil- or gas-fired. Because of the atmospheres used for
decreases with decreasing temperature. For each alloy suscep-
solution heat treatment, furnaces must be gas tight and contain
suitable equipment for the introduction of protective
atmospheres, and means for control of those atmospheres. In
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This practice is under the jurisdiction of ASTM Committee B07 on Light
ordertopromoteuniformityoftemperature,furnacesshouldbe
Metals and Alloys and is the direct responsibility of Subcommittee B07.04 on
Magnesium Alloy Cast and Wrought Products.
equipped with a high-velocity fan or comparable means for
Current edition approved March 1, 2006. Published March 2006. Originally
circulating the atmosphere. In the design of the furnace it is
approved in 1979. Last previous edition approved in 2003 as B661 – 03. DOI:
desirable that there be no direct radiation from the heating
10.1520/B0661-06.
2
elements or impingement of the flame on the magnesium.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.2 Automatic recording and control equipment to control
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the temperature of the furnaces, which must be capable of
*A Summary of Changes section appears at the end of this standard
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