ASTM D7646-10

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Designation: D7646 − 10
StandardTest Method for
Determination of Cooling Characteristics of Aqueous
Polymer Quenchants for Aluminum Alloys by Cooling Curve
Analysis
This standard is issued under the fixed designation D7646; 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.
1. Scope 2.4 Wolfson Engineering Group Specification:
Laboratory Tests forAssessing the Cooling Curve of Indus-
1.1 Thistestmethodcoversthedescriptionoftheequipment
trial Quenching Media
and the procedure for evaluating quenching characteristics of
aqueous polymer quenchants by cooling rate determination.
3. Terminology
1.2 This test method is designed to evaluate aqueous poly-
3.1 Definitions of Terms Specific to This Standard:
mer quenchants for aluminum alloys in a non-agitated system.
3.1.1 aqueous polymer quenchant, n—aqueous solution
Thereisnocorrelationbetweenthesetestresultsandtheresults
containing a water soluble polymer; typically including poly-
obtained in agitated systems.
(alkylene glycol), poly(ethyl oxazoline), poly(sodium acrylate)
1.3 The values stated in SI units are to be regarded as
and poly(vinyl pyrrolidone). The quenchant solution also
standard. No other units of measurement are included in this
typically contains additives for corrosion and foam control, if
standard.
needed. Quench severity of aqueous polymer quenchants is
1.4 This standard does not purport to address all of the
dependent on concentration and molecular weight of the
safety concerns, if any, associated with its use. It is the
specific polymer being evaluated, quenchant temperature, and
responsibility of the user of this standard to establish appro-
agitation rate.
priate safety and health practices and determine the applica-
3.1.2 characteristic temperature, n—transition temperature
bility of regulatory limitations prior to use.
from vapor blanket phase (film boiling phase) to rapid cooling
phase (nucleate boiling phase) on cooling curve.
2. Referenced Documents
3.1.3 cooling curve, n—cooling curve is a graphical repre-
2.1 ASTM Standards:
sentation of the cooling time (t)–temperature (T) response of
D6200 Test Method for Determination of Cooling Charac-
the probe (see 7.3). An example is illustrated in Part B of Fig.
teristics of Quench Oils by Cooling Curve Analysis
1.
E220 Test Method for Calibration of Thermocouples By
Comparison Techniques
3.1.4 cooling curve analysis, n—the process of quantifying
E230 Specification and Temperature-Electromotive Force
the cooling characteristics of a heat treating oil based on the
(EMF) Tables for Standardized Thermocouples
temperature versus time profile obtained by cooling a pre-
2.2 ISO Standards:
heated metal probe assembly (see Fig. 2) under standard
ISO 3819 Laboratory glassware — Beakers
conditions.
2.3 Japanese Industrial Standards:
3.1.5 cooling rate curve, n—The cooling rate curve is
JIS K 2242 Heat Treating Oil
obtained by calculating the first derivative (dT/dt)ofthe
cooling time–temperature curve. An example is illustrated in
This test method is under the jurisdiction of ASTM Committee D02 on
Part B of Fig. 1.
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.L0.06 on Non-Lubricating Process Fluids.
3.1.6 quench severity, n—the ability of a quenching medium
Current edition approved July 1, 2010. Published August 2010. DOI:10.1520/
to extract heat from a hot metal.
D7646-10.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.1.7 quenchant, n—any medium, liquid, or gas that may be
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
used to mediate heat transfer during the cooling of hot metal.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Available from Society ofAutomotive Engineers, International, 400 Common-
wealth Dr., Warrendale, PA 15096-0001.
Available from Japanese Standards Association, 4-1-24, Akasaka Minato-ku, Available from Wolfson Heat Treatment Centre, Aston University, Aston
Tokyo 107–8440, Japan. Triangle, Birmingham B4 7ET, England.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7646 − 10
FIG. 1 Typical Temperature/Time and Temperature/Cooling Rate Plots for Test Probe Cooled in an Aqueous Polymer Quenchant
4. Summary of Test Method variationinthetestprobeassemblyoftemperaturewithrespect
to time, and cooling rate with respect to temperature.
4.1 Determine the silver rod probe assembly’s cooling time
versus temperature after placing the assembly in a furnace and
7.3 Probe—Shall be cylindrical, having a diameter of 10 6
heating to 500°C and then quenching in an aqueous polymer
0.1 mm and a length of 30 6 0.1 mm with a 1.0 mm sheathed
quenchant solution.The temperature inside the probe assembly
Type K thermocouple in its geometric center. The probe shall
and the cooling times are recorded at selected time intervals to
be made of a silver of purity 99.99% or more. The probe shall
establish a cooling temperature versus time curve. The result-
be attached to a support tube. See Fig. 2 for recommended
ing cooling curve may be used to evaluate quench severity.
manufacturing details. Preparation method for silver rod shall
be as follows:
5. Significance and Use
7.3.1 Screw the connecting rod of heat–resistant steel in the
5.1 This test method provides a cooling time versus tem-
silver rod body.
perature pathway.The results obtained by this test method may
7.3.2 Insert the sheath type thermocouple through the sup-
be used as a guide in quenchant selection or comparison of
porting rod and supporting part.
quench severities of different quenchants, new or used.
7.3.3 Screw the connecting rod of heat resistant steel in the
supportingpartasinsertingthesheathtypethermocoupleinthe
6. Interferences
central part of silver rod body.
6.1 The presence of contaminants, such as oil, salt, metal-
7.3.4 Screw the supporting part in the supporting rod to
working fluids, forging lubricants, and polymer degradation,
connect.
may affect cooling curve results obtained by this test method
7.3.5 Fix the thermocouple connecting part to the support-
for aqueous polymer quenchants.
ing rod by using a set screw while pushing the sheath type
7. Apparatus thermocoupleinthedirectionofsilverrodbody.Insuchacase,
take care so that the tip of thermocouple is completely pressed
7.1 Furnace—Use a horizontal or vertical electrical resis-
to the central part of silver rod body.
tance tube-type furnace capable of maintaining a constant
7.3.6 Heat the temperature of the silver rod body and
minimum temperature of 850°C over a heated length of not
supporting part at 700 to 800°C, and coat the connecting part
less than 120 mm and a probe positioned in the center of the
with the crystal of silver nitrate and joint them.
heating chamber. The furnace shall be capable of maintaining
the probe’s temperature within 62.5°C over the specimen 7.3.7 After cooling, finish the surface smoothly by using
length. The furnace, that is, the radiant tube heating media, emerypapers.Althoughcoarser320-gritpapermaybeusedfor
shall be used with ambient atmosphere. initial cleaning, the final finish shall be provided using 500-grit
emery paper.
NOTE 1—Although the probe temperature is significantly lower 500°C
than the recommended furnace temperature capability 850°C, this higher
7.4 Fluid Volume—The resulting cooling curve will be
temperature capability is recommended since the same apparatus may be
dependent on the temperature rise during the quench, which is
used for cooling curve analysis for steel alloys which is performed at 805
dependent on the total fluid volume. Therefore, the cooling
to 815°C.
curve analysis shall be performed with the same volume of
7.2 Measurement System—The temperature–time measure-
fluid.
ment system shall be a computer based data acquisition system
capable of providing a permanent record of the cooling 7.5 Sample Container—300 mL beaker specified in ISO
characteristics of each oil sample tested, producing a record of 3819.
D7646 − 10
FIG. 2 Probe Details and General Probe Assembly
7.6 Temperature Measurement—Any temperature detection 7.7 Transfer Mechanism—One of the following shall be
device may be used that is capable of measuring quenching used to transfer the heated probe from the furnace to the test
fluid temperature to within 61°C. fluid:
D7646 − 10
7.7.1 Automated Transfer Mechanism—The transfer from prior to returning to the furnace. (Warning—The probe shall
the furnace to the oil shall be completed within 3.0 s. Immerse always be considered hot, as temperature below visual hot
the probe in the center, 0 to 5 mm, of the fluid container to a temperatures can still cause injury to the skin.) A cleaning
depth where there is 50 6 2 mm of fluid above and below the solvent may be used, but care should be taken that the probe is
probe when quenched. A mechanical stop shall be used for below 50°C. (Warning—Do not use cleaning solvent near the
reproducibility of probe placement. furnace opening, especially with automated transfer mecha-
7.7.2 Manual Transfer—If manual transfer is used, the nisms.).Water may be also be used as a cleaning solvent which
sample container shall be equipped with a fixture to ensure may by followed by polishing (see 9.2).
correct placement in the center of the fluid container and to the
9.2 Polishing Used Probes Using Emery Paper—Polish
depth defined in 7.4. A timer shall be used to ensure a
probe surface lightly at every trial using 500-grit emery paper
maximum transfer time of 3.0 s.
until its metallic luster is recovered.
7.8 Timer—Graduated in seconds and minutes; may be part
10. Sampling
of a computer clock.
10.1 Sampling shall be in accordance with 7.5. Take care to
7.9 Fluid Volume—The resulting cooling curve will be
ensure the sample is representative of the quenchant being
dependent on the temperature rise during the quench, which is
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