ASTM E8 is a widely recognized standard for tensile testing of metallic materials. This test measures a material's mechanical properties by subjecting a sample to a controlled axial load, which helps determine factors such as yield strength, ultimate tensile strength, and elongation. It is a crucial method for assessing a material's performance and suitability for various applications, especially in engineering and manufacturing.

1. TENSILE TESTING STANDARDS
TENSILE TESTING- ASTM E8
NAME- YASH JANARDAN SHINDE
EN ROLL- 220133121025

2.  The ASTM E8 / ASTM E8M standard describes uniaxial
tensile testing of metals at room temperature and the
determination of characteristic values including yield
strength, yield point, yield point elongation, tensile
strength, strain at break and reduction of area. The values
can be used to make predictions about the strength and
toughness of the material.

3.  Important information is provided for specimen preparation, to ensure that the
machining process and the subsequent specimen preparation do not influence
the material, since this could in turn affect the results of the tensile test.
 There can be a wide range of shapes for tensile specimens. ASTM E8/ASTM
E8M lists standard flat specimens for sheet metals and thin sheet metals, for
tubular products, for special specimen grips, and standard round specimens for
other metal products, and specifies the corresponding initial gauge lengths to
which all strain values refer. With a few exceptions, all dimensions that are
needed for specimen preparation are specified, or else minimum dimensions
are indicated.
Both the specimen shape and the specimen machining process are defined
in the ASTM E8 test standard. Specimens must be prepared in such a way that
the material properties are not influenced. All areas that were strain hardened
through cutting or punching during the specimen machining process must be
processed accordingly, if they have an effect on the specimen properties.
 Products with a constant cross section (profiles, bars, wires, etc.) and cast
specimens
 (e.g. cast iron, nonferrous alloys) can be tested without processing. Preferred
specimen shapes according to ASTM E8 are flat specimens (shouldered-end)
and round specimens.

4. Illustration (a) shows the flat
specimen, illustration (b)
shows the round specimen.
The illustration shows the flat specimen
(top) and the round specimen (bottom)
with the respective dimensions (right, in
mm).

5. YouTube video
https://youtu.be/axARl-AT66Y

6. Particular focus is on the test speed. ASTM E8 support five
different ways of specifying test speeds. They are designated
as
 (a) Rate of straining of the specimen,
 (b) Rate of stressing of the specimen,
 (c) Crosshead speed
 (d) The elapsed time for completing part or all of the test,
 (e) Free-running crosshead speed (rate of movement of the
crosshead of the testing machine when not under load).

7. Test speeds / control methods according to ASTM E8
Control method B:
•closed loop strain rate
control
Recommended method
Control method C:
•crosshead speed
Control method A:
•stress speed
•Extensometer required •Extensometer required •No extensometer
required
•No pre-testing or setup
required (adaptive
controller)
•Pre-testing and setup
required (determination of
the testing system and
specimen stiffness)
•Pre-testing and setup
required (determination
of the testing system and
specimen stiffness)

8. Method A is based on the increase in tensile stress
during load application.
 In the linear elastic part of the tensile test, that is at
the very beginning of the test, the rate of stress
application must be between 1.15 and 11.5
MPa/sec (this corresponds to 10000 and 100000
psi/min).

9. Method B is based on the control of the strain speed or
strain rate (strain rate control) during the load
application.
 The testing machine keeps the closed loop strain rate
constant by using an extensometer to continuously
provide strain values that are used to calculate the
precise strain rate.

10. Method C is based on constant speed of the
crosshead.
 The crosshead speed shall be set and kept constant so
that the initial parallel length of the specimen
undergoes an elongation of 0.015 ± 0.003
in./in./min or mm/mm/min.

11. 1) zwickroell.com
2) Material science and Metallurgy by V.D. Kodgire