ASTM B91-17

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
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Designation: B91 − 12 B91 − 17
Standard Specification for
Magnesium-Alloy Magnesium-Alloy Forgings
This standard is issued under the fixed designation B91; 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 U.S. Department of Defense.
1. Scope*
1.1 This specification covers magnesium alloy forgings designated as shown in Table 1.
1.2 The values stated in inch-pound units are the standard. The SI values in parentheses are provided for information only.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 The following documents of the issue in effect on date of material purchase form a part of this specification to the extent
referenced herein:
2.2 ASTM Standards:
B296 Practice for Temper Designations of Magnesium Alloys, Cast and Wrought
B557 Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products
B660 Practices for Packaging/Packing of Aluminum and Magnesium Products
B666 Practice for Identification Marking of Aluminum and Magnesium Products
B951 Practice for Codification of Unalloyed Magnesium and Magnesium-Alloys, Cast and Wrought
B953 Practice for Sampling Magnesium and Magnesium Alloys for Spectrochemical Analysis
B954 Test Method for Analysis of Magnesium and Magnesium Alloys by Atomic Emission Spectrometry
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E55 Practice for Sampling Wrought Nonferrous Metals and Alloys for Determination of Chemical Composition
2.3 Federal Standards:
No. 123FED-STD-123H Marking for Shipment (Civil Agencies)
No. 184 Identification Marking of Aluminum, Magnesium, and Titanium.
2.4 Military Standards:
MIL-STD-129 Marking for Shipment and Storage (Military Agencies)
2.5 Aerospace Materials Specification:
AMS-M-3171 Magnesium Alloy, Processes for Pretreatment and Prevention of Corrosion on
3. Terminology
3.1 Definitions:
3.1.1 forging—a metal part worked to a predetermined shape by one or more such processes as hammering, upsetting, pressing,
or rolling.
3.1.2 die forging—a forging formed to the required shape and size by working in impression dies.
3.1.3 hammer forging—a forging produced by repeated blows in a forging hammer.
This specification is under the jurisdiction of ASTM Committee B07 on Light Metals and Alloys and is the direct responsibility of Subcommittee B07.04 on Magnesium
Alloy Cast and Wrought Products.
Current edition approved Nov. 1, 2012May 1, 2017. Published November 2012May 2017. Originally approved in 1932. Last previous edition approved in 20072012 as
B91 – 07.B91 – 12. DOI: 10.1520/B0091-12.10.1520/B0091-17.
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://www.dodssp.daps.mil.
Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale, PA 15096-0001, http://www.sae.org.
*A Summary of Changes section appears at the end of this standard
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B91 − 17
A,B
TABLE 1 Chemical Composition Limits
NOTE 1—Analysis shall regularly be made only for the elements specifically mentioned in this table. If, however, the presence of other elements is
suspected or indicated in amounts greater than the specified limits, further analysis shall be made to determine that these elements are not present in excess
of the specified limits.
NOTE 2—The following applies to all specified limits in this table. For purposes of acceptance and rejection, an observed value or a calculated value
obtained from analysis should be rounded to the nearest unit in the last right-hand place of figures used in expressing the specified limit.
Composition, %
Alloy AZ31B Alloy AZ61A Alloy AZ80A Alloy ZK60A
Element (UNS No. (UNS No. (UNS No. (UNS No.
M11311) M11610) M11800) M16600)
Magnesium remainder remainder remainder remainder
Aluminum 2.5–3.5 5.8–7.2 7.8–9.2 .
Manganese 0.20–1.0 0.15–0.5 0.12–0.5 .
Zinc 0.6–1.4 0.40–1.5 0.20–0.8 4.8–6.2
Thorium . . . .
Zirconium, min . . 0.45
Silicon 0.10 0.10 0.10 .
Copper 0.05 0.05 0.05 .
Nickel 0.005 0.005 0.005 .
Iron 0.005 0.005 0.005 .
Calcium 0.04 . . .
C
Other impurities 0.30 0.30 0.30 0.30
A
Limits are in weight percent maximum unless shown as a range or stated otherwise.
B
These alloy designations were established in accordance with Practice B951.
C
Includes listed elements for which no specific limit is shown.
3.1.4 hand forging—a forging worked between flat or simply shaped dies by repeated strokes or blows and manipulation of the
piece.
4. Ordering Information
4.1 Orders for forgings under this specification shall include the following information:
4.1.1 Quantity of each forging,
4.1.2 Alloy (Section 6 and Table 1),
4.1.3 Temper (Section 7 and Table 2), ) in accordance with the requirements of Practice B296,
4.1.4 Drawing showing dimensions of all die forgings and for all hand forgings not simple disks, rounds, squares, or rectangles
(the amount of stock left for machine finish should be indicated),
4.1.5 Surface treatment (see 9.1),
4.1.6 Whether inspection is required at the manufacturer’s works (see 10.1),
4.1.7 Special inspection requirements (see 10.2),
4.1.8 Whether certification is required (see 12.1), and
TABLE 2 Tensile Requirements
NOTE 1—For purposes of determining conformance with this
specification, each value for tensile strength and yield strength shall be
rounded to the nearest 0.1 ksi (0.7 MPa) and each value for elongation
shall be rounded to the nearest 0.5 %, both in accordance with the
rounding method of Practice E29.
Elongation
Tensile
Yield
in 2 in.
A
Alloy and Strength, Strength (0.2
(51 mm), or
% offset),
Temper min, ksi
4 × dia,
min, ksi
(MPa)
(MPa) min, %
AZ31B–F 34.0 (234) 19.0 (131) 6
AZ61A–F 38.0 (262) 22.0 (152) 6
AZ80A–F 42.0 (290) 26.0 (179) 5
AZ80A–T5 42.0 (290) 28.0 (193) 2
ZK60A–T5 die 42.0 (290) 26.0 (179) 7
B
forgings
ZK60A–T6 die 43.0 (296) 32.0 (221) 4
B
forgings
A
See X1.1.6.
B
Applicable only to die forgings not more than 3 in. (76 mm) in thickness. The
tensile requirements for hand forgings will be lower and as agreed upon by the
purchaser and manufacturer.
B91 − 17
4.1.9 Whether marking for identification is required (see 13.1).
5. Quality Assurance
5.1 The manufacturer shall be responsible for the performance of all inspection and tests required by this specification, prior
to shipment of the material.
6. Chemical Composition
6.1 Limits—The material shall conform to the chemical composition limits prescribed in Table 1. The manufacturer shall
determine conformance by analyzing samples taken when the ingots are poured, or by analyzing samples taken from the finished
or semi-finished product. If the manufacturer has determined the chemical composition during the course of manufacture, he shall
not be required to sample and analyze the finished product.
6.2 Number of Samples—The number of samples taken for determination of chemical composition shall be as follows:
6.2.1 When samples are taken at the time the ingots are poured, at least one sample shall be taken for each group of ingots
poured simultaneously from the same source of molten metal.
6.2.2 When samples are taken from the finished or semi-finished product, a sample shall be taken to represent each 2000 lb (905
kg), or fraction thereof, in the shipment, except that not more than one sample shall be required per piece.
6.3 Methods of Sampling—Samples for determination of chemical composition shall be taken in accordance with one of the
following methods:
6.3.1 Samples for chemical analysis shall be taken from the material by drilling, sawing, milling, turning, or clipping a
representative piece or pieces to obtain a weight of prepared sample not less than 75 g. Sampling shall be in accordance with
Practice E55.
6.3.2 Samples for spectrochemical analysis shall be in accordance with Practice B953, or other methods of analysis shall be
taken by methods suitable for the form of material being analyzed and the type of analytical method used.
6.4 Methods of Chemical Analysis—Any suitable method of chemical analysis may be used. In case of dispute, the analysis shall
be made by methods given in Test Method B954 or any other standard methods of analysis approved by ASTM unless some other
method is agreed upon.
7. Tensile Properties
7.1 Limits—The forgings shall conform to the tensile properties prescribed in Table 2.
7.2 Number of Specimens—One tension test specimen shall be taken to represent each 1000 lb (455 kg) or fraction thereof of
each part number in the shipment or inspection lot.
7.2.1 When specified, a grain flow pattern and tensile-property survey shall be made on a forging representative of the first
production parts (see 7.3.1). It shall be repeated after any major change in forging technique.
7.3 Test Specimens—Tension test specimens shall be taken from a forging or from a separately forged coupon made from
material representative of the forgings, in such a manner that the lo
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