ASTM E2448-08

Standard Test Method for Determining the Superplastic Properties of Metallic Sheet Materials

SIGNIFICANCE AND USE
The determination of the superplastic properties of a metallic sheet material is important for the observation, development and comparison of superplastic materials. It is also necessary to predict the correct forming parameters during an SPF process. SPF tensile testing has peculiar characteristics compared to conventional mechanical testing, which distort the true values of stress, strain, strain hardening, and strain rate at the very large elongations encountered in an SPF pull test, consequently conventional mechanical test methods cannot be used. This test method addresses those characteristics by optimizing the shape of the test coupon and specifying a new test procedure.
The evaluation of a superplastic material can be divided into two parts. Firstly, the basic superplastic-forming (SPF) properties of the material are measured using the four parameters of stress, temperature, strain, and strain rate. These are obtained using conversions from the raw data of a tensile test. Secondly, derived properties useful to define an SPF material are obtained from the basic properties using specific equations.
SCOPE
1.1 This test method describes the procedure for determining the superplastic forming properties (SPF) of a metallic sheet material. It includes tests both for the basic SPF properties and also for derived SPF properties. The test for basic properties encompasses effects due to strain hardening or softening.  
1.2 This test method covers sheet materials with thicknesses of at least 0.5 mm but not greater than 6 mm. It characterizes the material under a uni-axial tensile stress condition.
Note 1—Most industrial applications of superplastic forming involve a multi-axial stress condition in a sheet; however it is more convenient to characterize a material under a uni-axial tensile stress condition. Tests should be performed in different orientations to the rolling direction of the sheet to ascertain initial anisotropy.
1.3 This method has been used successfully between strain rates of 10-5 to 10-1 per second.
1.4 This method has been used successfully on Aluminum and Titanium alloys. The use of the method with other metals should be verified.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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.

General Information

• Status: Historical
• Publication Date: 30-Nov-2008
• ICS: 77.140.50 - Flat steel products and semi-products
• Technical Committee: E28 - Mechanical Testing
• Drafting Committee: E28.02 - Ductility and Formability

Relations

• Replaces: ASTM E2448-06 - Standard Test Method for Determining the Superplastic Properties of Metallic Sheet Materials
• Effective Date: 01-Dec-2008
• Replaced By: ASTM E2448-11 - Standard Test Method for Determining the Superplastic Properties of Metallic Sheet Materials
• Effective Date: 01-Jun-2011
• Referred By: ASTM E633-21a - Standard Guide for Use of Thermocouples in Elevated-Temperature Mechanical Testing
• Effective Date: 01-Dec-2008
• Referred By: ASTM E2712-22 - Standard Test Methods for Bulge-Forming Superplastic Metallic Sheet
• Effective Date: 01-Dec-2008

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E2448 – 08
Standard Test Method for
Determining the Superplastic Properties of Metallic Sheet
1
Materials
This standard is issued under the fixed designation E2448; 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 E6 TerminologyRelatingtoMethodsofMechanicalTesting
E21 Test Methods for Elevated Temperature Tension Tests
1.1 This test method describes the procedure for determin-
of Metallic Materials
ing the superplastic forming properties (SPF) of a metallic
E177 Practice for Use of the Terms Precision and Bias in
sheet material. It includes tests both for the basic SPF proper-
ASTM Test Methods
ties and also for derived SPF properties. The test for basic
E646 Test Method for Tensile Strain-Hardening Exponents
properties encompasses effects due to strain hardening or
(n -Values) of Metallic Sheet Materials
softening.
E691 Practice for Conducting an Interlaboratory Study to
1.2 This test method covers sheet materials with thicknesses
Determine the Precision of a Test Method
of at least 0.5 mm but not greater than 6 mm. It characterizes
the material under a uni-axial tensile stress condition.
3. Terminology
NOTE 1—Most industrial applications of superplastic forming involve a
3.1 Definitions—Definitions such as gage length (L and L ),
0
multi-axial stress condition in a sheet; however it is more convenient to
true stress (s), true strain (´), normal engineering stress (S),
characterize a material under a uni-axial tensile stress condition. Tests
andengineeringstrain(e)aredefinedinTerminologyE6.Thus,
should be performed in different orientations to the rolling direction of the
sheet to ascertain initial anisotropy. ´5 ln L/L !
~
0
1.3 This method has been used successfully between strain s5 S~1 1 e!
-5 -1
rates of 10 to 10 per second.
NOTE 2—Engineering stress S and strain e are only valid up to the point
1.4 This method has been used successfully on Aluminum
ofneckingorinstabilityofcrosssection.Forsuperplasticdeformation,the
and Titanium alloys. The use of the method with other metals
coupon undergoes an essentially uniform and constant neck along its
should be verified.
length, and S and e are assumed in this standard to be valid. However at
the junction to the clamp sections of the coupon the cross section reduces
1.5 The values stated in SI units are to be regarded as
from the original value to the final value, over a length of approximately
standard. No other units of measurement are included in this
4 % at each end. Also, there are local small instabilities of cross section
standard.
overthegaugelength.Thesecontributetoanerrorinthecalculatedvalues
1.6 This standard does not purport to address all of the
of ´ and s. In the absence of currently available extensometers that could
safety concerns, if any, associated with its use. It is the
operate in the high temperature environment of an SPF test, ´ and s are
responsibility of the user of this standard to establish appro-
to be inferred from crosshead extension and force.
priate safety and health practices and determine the applica-
3.2 Symbols Specific To This Standard:
bility of regulatory limitations prior to use.
V = machine crosshead velocity, the velocity of the traveling
memberofthetestmachinetowhichoneofthecouponclamps
2. Referenced Documents
is attached
2
2.1 ASTM Standards:
·
´ = strain rate, measured as: V/@L ~1 1 e!#
0
E4 Practices for Force Verification of Testing Machines
NOTE 3—This is an operational definition of strain rate.
1
·
This test method is under the jurisdiction of ASTM Committee E28 on
m = strain rate sensitivity, defined as (ln Ds)/ (ln D´). In
Mechanical Testing and is the direct responsibility of Subcommittee E28.02 on
· ·
Ductility and Formability. practical terms, m = log (s /s )/log (´ /´ ) under stated test
2 1 2 1
Current edition approved Dec. 1, 2008. Published January 2009. Originally
conditions, see 7.2.1.
approved in 2005. Last previous edition approved in 2006 as E2448–06. DOI:
10.1520/E2448-08.
NOTE 4—The derived term m is widely used to describe the SPF
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
properties of a material. It should be used with caution, as it is dependent
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
on strain, strain rate and temperature. Many references in the literature do
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
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
of the standard as published by ASTM is to be considered the official document.
Designation:E2448–06 Designation: E 2448 – 08
Standard Test Method for
Determining the Superplastic Properties of Metallic Sheet
1
Materials
This standard is issued under the fixed designation E 2448; 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
1.1 This test method describes the procedure for determining the superplastic forming properties (SPF) of a metallic sheet
material. It includes tests both for the basic SPF properties and also for derived SPF properties. The test for basic properties
encompasses effects due to strain hardening or softening.
1.2 This test method covers sheet materials with thicknesses of at least 0.5 mm but not greater than 6 mm. It characterizes the
material under a uni-axial tensile stress condition.
NOTE 1—Most industrial applications of superplastic forming involve a multi-axial stress condition in a sheet; however it is more convenient to
characterize a material under a uni-axial tensile stress condition. Tests should be performed in different orientations to the rolling direction of the sheet
to ascertain initial anisotropy.
-5 -1
1.3 This method has been used successfully between strain rates of 10 to 10 per second.
1.4 This method has been used successfully onAluminum andTitanium alloys.The use of the method with other metals should
be verified.
1.5The values given in SI units are to be considered the standard.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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.
2. Referenced Documents
2
2.1 ASTM Standards:
E4 Practices for Force vVerification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E21 Test Methods for Elevated Temperature Tension Tests of Metallic Materials
E 177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E 646 Test Method for Tensile Strain Hardening Exponents (n-Values) of Metallic Materials Test Method for Tensile
Strain-Hardening Exponents (n -Values) of Metallic Sheet Materials
E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions—Definitions such as gage length (L and L ), true stress (s), true strain (´), normal engineering stress (S), and
0
engineering strain (e) are defined in Terminology E 6. Thus,
´5 ln~ L/L !
0
s5 S~1 1 e!
NOTE 2—Engineering stress S and strain e are only valid up to the point of necking or instability of cross section. For superplastic deformation, the
coupon undergoes an essentially uniform and constant neck along its length, and S and e are assumed in this standard to be valid. However at the junction
to the clamp sections of the coupon the cross section reduces from the original value to the final value, over a length of approximately 4 % at each end.
Also, there are local small instabilities of cross section over the gauge length. These contribute to an error in the calculated values of ´ and s.Inthe
1
This test method is under the jurisdiction of ASTM Committee E28 on Mechanical Testing and is the direct responsibility of Subcommittee E28.02 on Ductility and
Flexure Testing. Formability.
Current edition approved MayDec. 1, 2006.2008. Published June 2006.January 2009. Originally approved in 2005. Last previous edition approved in 20052006 as
E 2448–056.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
E2448–08
absence of currently available extensometers that could operate in the high temperature environment of an SPF test, ´ and s are to be inferred from
crosshead extension and force.
3.2 Symbols Specific To This Standard :
V = machine crosshead velocity, the velocity of the traveling member of t
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
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
of the standard as published by ASTM is to be considered the official document.
Designation:E2448–06 Designation: E 2448 – 08
Standard Test Method for
Determining the Superplastic Properties of Metallic Sheet
1
Materials
This standard is issued under the fixed designation E 2448; 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
1.1 This test method describes the procedure for determining the superplastic forming properties (SPF) of a metallic sheet
material. It includes tests both for the basic SPF properties and also for derived SPF properties. The test for basic properties
encompasses effects due to strain hardening or softening.
1.2 This test method covers sheet materials with thicknesses of at least 0.5 mm but not greater than 6 mm. It characterizes the
material under a uni-axial tensile stress condition.
NOTE 1—Most industrial applications of superplastic forming involve a multi-axial stress condition in a sheet; however it is more convenient to
characterize a material under a uni-axial tensile stress condition. Tests should be performed in different orientations to the rolling direction of the sheet
to ascertain initial anisotropy.
-5 -1
1.3 This method has been used successfully between strain rates of 10 to 10 per second.
1.4 This method has been used successfully onAluminum andTitanium alloys.The use of the method with other metals should
be verified.
1.5The values given in SI units are to be considered the standard.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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.
2. Referenced Documents
2
2.1 ASTM Standards:
E4 Practices for Force vVerification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E21 Test Methods for Elevated Temperature Tension Tests of Metallic Materials
E 177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E 646 Test Method for Tensile Strain Hardening Exponents (n-Values) of Metallic Materials Test Method for Tensile
Strain-Hardening Exponents (n -Values) of Metallic Sheet Materials
E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions—Definitions such as gage length (L and L ), true stress (s), true strain (´), normal engineering stress (S), and
0
engineering strain (e) are defined in Terminology E 6. Thus,
´5 ln~ L/L !
0
s5 S~1 1 e!
NOTE 2—Engineering stress S and strain e are only valid up to the point of necking or instability of cross section. For superplastic deformation, the
coupon undergoes an essentially uniform and constant neck along its length, and S and e are assumed in this standard to be valid. However at the junction
to the clamp sections of the coupon the cross section reduces from the original value to the final value, over a length of approximately 4 % at each end.
Also, there are local small instabilities of cross section over the gauge length. These contribute to an error in the calculated values of ´ and s.Inthe
1
This test method is under the jurisdiction of ASTM Committee E28 on Mechanical Testing and is the direct responsibility of Subcommittee E28.02 on Ductility and
Formability.
Current edition approved MayDec. 1, 2006.2008. Published June 2006.January 2009. Originally approved in 2005. Last previous edition approved in 20052006 as
E 2448–056.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
E2448–08
absence of currently available extensometers that could operate in the high temperature environment of an SPF test, ´ and s are to be inferred from
crosshead extension and force.
3.2 Symbols Specific To This Standard :
V = machine crosshead velocity, the velocity of the traveling member of the test machine t
...