ASTM B917/B917M-01(2005)
(Practice)Standard Practice for Heat Treatment of Aluminum-Alloy Castings from All Processes
Standard Practice for Heat Treatment of Aluminum-Alloy Castings from All Processes
SCOPE
1.1 This practice is intended, when specified by material specification or purchase order, for the use in the heat treatment of aluminum alloy castings from all casting processes.
1.1.1 The heat treatment of aluminum alloy castings used in specific aerospace applications is covered in AMS 2771 and specific AMS material specifications.
1.1.2 The heat treatment of wrought aluminum alloys is covered in Practice B 918.
1.2 The values stated in either inch-pound units or SI units are to be regarded separately as standards. The SI units are shown in brackets or in separate tables. The values stated in each system are not exact equivalents, therefore each system must be used independent of the other. Combining values from the two systems may result in non-conformance with the practice.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the usre 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:B917/B917M–01 (Reapproved 2005)
Standard Practice for
Heat Treatment of Aluminum-Alloy Castings from All
Processes
This standard is issued under the fixed designation B 917/B 917M; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope als and Alloys, Cast and Wrought
B 557 Test Methods of Tension Testing Wrought and Cast
1.1 This practice is covers, when specified by material
Aluminum and Magnesium-Alloy Products
specificationorpurchaseorder,theheattreatmentofaluminum
B 557M TestMethodsofTensionTestingWroughtandCast
alloy castings from all casting processes.
Aluminum and Magnesium- Alloy Products [Metric]
1.1.1 The heat treatment of aluminum alloy castings used in
2 B 618 Specification for Aluminum-Alloy Investment Cast-
specific aerospace applications is covered in AMS 2771 and
ings
specific AMS material specifications.
B 686 Specification for Aluminum-Alloy Castings, High
1.1.2 The heat treatment of wrought aluminum alloys is
Strength
covered in Practice B 918.
B 881 Terminology Relating to Aluminum- and
1.2 The values stated in either inch-pound units or SI units
Magnesium-Alloy Products
are to be regarded separately as standards. The SI units are
B 918 Practice for Heat Treatment of Wrought Aluminum
shown in brackets or in separate tables. The values stated in
Aloys
each system are not exact equivalents, therefore each system
G110 Practice for Evaluating Intergranular Corrosion Re-
must be used independent of the other. Combining values from
sistance of Heat Treatable Aluminium Alloys by Immer-
the two systems may result in non-conformance with the
sion in Sodium Chloride + Hydrogen Peroxide Solution
practice.
2.3 ANSI Standard:
1.3 This standard does not purport to address all of the
H35.1 Alloy and Temper Designation Systems for Alumi-
safety concerns, if any, associated with its use. It is the
num
responsibility of the usre of this standard to establish appro-
priate safety and health practices and determine the applica-
3. Terminology
bility of regulatory limitations prior to use.
3.1 Definitions:
2. Referenced Documents 3.1.1 Refer to Terminology B 881 for terminology relating
to the heat treatment of castings.
2.1 The following documents of the issue in effect on the
dateofmaterialpurchaseformapartofthisspecificationtothe
4. Equipment
extent referenced herein:
3 4.1 Heating Media—Aluminum castings are typically heat
2.2 ASTM Standards:
treated in air chamber furnaces; however, lead baths, oil baths,
B 26/B 26M Specification for Aluminum-Alloy Sand Cast-
fluidized beds, or even superheated steam may be used in
ings
specific applications. The use of uncontrolled heating is not
B 108 Specification for Aluminum-Alloy Permanent Mold
permitted. Whichever heating means are employed, careful
Castings
evaluation is required to ensure that the casting responds
B 275 Practice for Codification of Certain Nonferrous Met-
properly to heat treatment and is not overheated or damaged by
the heat treatment environment. Salt baths are not recom-
mended for the commercial heat treatment of aluminum
This practice is under the jurisdiction of ASTM Committee B07 on Light
castings in volume. (Warning—Nitrate baths must not be used
Metals and Alloys and is the direct responsibility of Subcommittee B07.01 on
in the heat treatment of 5xx.0 series castings because of the
Aluminum Alloy Ingots and Castings.
inherent explosion hazard.
Current edition approved Sept. 1, 2005. Published September 2005. Originally
approved in 2001. Last previous edition approved in 2001 as B 917/B 917M – 01. 4.2 Air Chamber Furnaces—may be oil or gas-fired or may
Available from Society of Automotive Engineers (SAE), 400 Commonwealth
be electrically heated. The atmosphere in air chamber furnaces
Dr., Warrendale, PA 15096-0001.
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 Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036.
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B917/B917M–01 (2005)
must be controlled to prevent porosity resulting from solution 5.2.2 A new temperature survey shall be made after any
heat treatment. Furnace components that are significantly modification, repair, adjustment (for example, to power con-
hotter than the metal should be suitably shielded for section trols, or baffles), or rebuild which may have altered the
thicknesses of less than 0.250 in. [6 mm] to prevent adverse temperature uniformity characteristics of the furnace and
radiation effects. The atmosphere in air chamber furnaces must
reduced the effectiveness of the heat treatment.
be controlled to prevent porosity resulting from solution heat
5.3 Batch Furnace Surveys:
treatment (see Note 1). The suitability of the atmosphere in an
5.3.1 The initial temperature survey shall be made at the
air-chamber furnace can be demonstrated by testing, in accor-
maximum and minimum temperature of solution heat treat-
dance with 8.4.3.1, that products processed in that furnace are
ments and precipitation heat treatments for which each furnace
substantially free of heat treat induced porosity.
is to be used. There shall be at least one test location for each
3 3
25 ft [0.70 m ] of air furnace volume up to a maximum of 40
NOTE 1—Heat treat induced porosity may lower mechanical properties
and commonly causes blistering of the surface of the material. The
test locations, with a minimum of nine test locations, one in
condition is most likely to occur in furnaces in which the products of
each corner and one in the center.
combustion contact the work, particularly if the gases are high in water
5.3.2 After the initial survey, each furnace shall be surveyed
vapor or contain compounds of sulfur. Surface discoloration is a normal
monthly, except as provided in 5.3.7.The monthly survey shall
result of solution heat treatment of aluminum alloys and should not be
be at one operating temperature for solution heat treatment and
interpreted as evidence of damage from overheating or as heat treat
induced porosity. one for precipitation heat treatment.
5.3.3 There shall be at least one test location for each 40 ft
4.3 Automatic Recording and Control Equipment—to con-
[1 m ] of load volume, with a minimum of nine test locations,
trol temperature of air furnaces shall be capable of maintaining
one in each corner and one in the center.
temperature in the working zone to within 610°F [65°C] of
the specified temperature. 5.3.4 The surveys shall reflect the normal operating charac-
teristics of the furnace. If the furnace is normally charged after
4.4 Quench Baths—Quenching is normally performed by
being stabilized at the correct operating temperature, the
immersion of castings in a hot-water bath as described in
temperature-sensing elements shall be similarly charged. If the
Tables 1-4. The water baths must be located close enough to
furnace is normally charged cold, the temperature-sensing
solutionheat-treatingfacilitiestominimizedelayinquenching.
Tanks must be of adequate size for the expected work load and elements shall be charged cold. After insertion of the
temperature-sensing elements, readings should be taken fre-
must have the means of providing adequate circulation of the
quenching media about the work load. Means for heating or quently enough to determine when the temperature of the
hottest region of the furnace approaches the bottom of the
cooling the quench water should be available when needed.
temperaturerangebeingsurveyed.Fromthattimeuntilthermal
NOTE 2—Quenching may be performed by alternative means such as
equilibrium is reached, the temperature of all test locations
total immersion in a glycol and water solution, a liquefied gas, cold water,
should be determined at 2-min intervals in order to detect any
hot water, or boiling water, or by air blast or fog to minimize distortion
over-shooting. After thermal equilibrium is reached, readings
provided samples from the material, so quenched, will conform to the (1)
mechanical properties, (2) other requirements of the applicable casting should be taken at 5-min intervals for sufficient time to
specification and (3) not exhibit more intergranular corrosion susceptibil-
determine the recurrent temperature pattern, but for not less
ity than if the metal was immersion quenched in cold water. The use of
than30min.Beforethermalequilibriumisreached,noneofthe
water sprays or high-velocity high-volume jets of water in which the
temperature readings should exceed the maximum temperature
material is thoroughly and effectively flushed is satisfactory for quench-
of the range being surveyed. After thermal equilibrium is
ing. Alternative quench media are frequently contingent on the particular
reached, the maximum temperature variation of all elements
alloy and the end use of the casting.
(both load and furnace thermocouples) shall not exceed 20°F
5. Furnace Temperature Uniformity and Calibration [10°C] and shall not vary outside the range being surveyed.
3 3
Requirements
5.3.5 Forfurnacesof10ft [0.25m ]orlessthetemperature
survey may be made with a minimum of three thermocouples
5.1 Calibration of Equipment:
located at front, center, and rear or at top, center, and bottom of
5.1.1 Thermocouple wire and sensors shall be calibrated
the furnace.
againstwireorsensorswhosecalibrationistraceabletoNIST).
Thermocouplesmadefromcalibratedwirerollsmaybeusedin 5.3.6 For furnaces used only for precipitation treatment,
lieuofindividuallycalibratedthermocouplesinwhichcase,the after the initial temperature-uniformity survey, as outlined in
roll calibration shall be that of the average of samples taken 5.3.7, surveys need not be made more often than at each
from both ends of the roll. The roll shall not be used if the 6-month interval provided that (1) test specimens from each lot
difference in the highest and lowest reading exceeds 2°F [1°C]. are tested and meet applicable material specifications require-
5.1.2 Working instruments shall be calibrated at least once ments, (2) the furnace is equipped with a multipoint recorder,
or (3) one or more separate load thermocouples are employed
every three months against a test instrument that is traceable to
NIST. Accuracy shall be 6 \0.3 % of range. to measure and record actual metal temperatures.
5.2 Furnace Temperature Survey:
5.3.7 Monthly surveys for batch furnaces are not necessary
5.2.1 A temperature survey, to ensure compliance with the when the furnace or bath is equipped with a permanent
applicable recommendations presented herein, shall be per- multipoint recording system with at least two sensing thermo-
formed for each furnace. couples in each zone or when one or more separate load
B917/B917M–01 (2005)
thermocouples are employed to measure actual metal tempera- 5.5 Monitoring of Quench—A monitoring plan shall be
ture, providing that uniformity surveys show a history of developed and utilized for all modes of quenching for all
satisfactory performance for a period of at least 6 months. The products covered by this practice. The plan should incorporate
sensing thermocouples shall be installed so as to record the conductivity or hardness checking, or both, to determine the
temperature of the heated media (air, lead, and so forth) or uniformity of the quench. Areas having substantially higher
actual metal temperatures. However, periodic surveys shall conductivity or lower hardness than other areas of similar
also be made at 6-month intervals in accordance with the thickness in the lot shall be investigated to ensure that the
procedures outlined for the monthly survey. requirements of the material specification are met.
5.4 Continuous Furnace Surveys: 5.6 Temperature-Measuring System Check—The accuracy
5.4.1 For continuous heat-treating furnaces, the type of of the temperature-measuring system shall be checked under
survey and the procedures for performing the survey should be operating conditions weekly. Check should be made by insert-
established for each particular furnace involved. The types of ing a calibrated test temperature-sensing element adjacent to
continuous heat-treating furnaces may vary considerably, de- the furnace temperature-sensing element and reading the test
pending upon the product and sizes involved. For some types temperature-sensing element with a calibrated test potentiom-
and sizes of furnaces, the only practical way to survey the eter. When the furnace is equipped with dual potentiometer
furnace is to perform an extensive mechanical property survey measuring systems which are checked daily against each other,
of the limiting product sizes to verify conformance with the the above checks may be conducted every 3 months rather than
specified mechanical properties for such items. When the type every week. The test temperature-sensing element, potentiom-
and size of the furnace makes this practical, monthly surveys eter, and cold junction compensation combination shall have
should be made, using a minimum of two load thermocouples been calibrated against NIST primary or secondary certified
attached to the material. The surveys should reflect the normal temperature-sensingelements,withintheprevious3months,to
operating characteristics of the furnace. The results of these an accuracy of 62°F [61°C].
surveys shall indicate that the metal temperature never exceeds 5.6.1 If the difference between the two readings in 5.6
the allowable maximum metal temperature specified for solu- exceeds 610°F [66°C], the cause of the difference shall be
tion heat treatment (Tables 1-4 as appropriate) after all load determined and corrected before commencing additional ther-
thermocouples have reached the minimum metal temperature mal processing. The responsible quality organization shall be
specified. notified and appropriate corrective action shall be taken and
5.4.2 Furnace control temperature-measuring instruments documented including an evaluation of the possible effects of
shallnotbeusedtoreadthetemperatureofthetesttemperature the deviation on castings processed since the last successful
sensing elements. test.
TABLE 1 Recommended Heat Treatment for Sand and Investment Type Alloys (Inch-Pound Units)
B,C D
Solution Heat Treatment Precipitation Heat Treatment
A A
Alloy Fi
...
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