ASTM E646 is the test method for determining the tensile strain-hardening exponent, the n-value, of metallic sheet materials from tensile stress-strain data. To match a setup to this test, talk with our team.
What ASTM E646 Measures
The n-value describes how a sheet metal work-hardens during plastic deformation, which relates directly to its formability and stretchability. The method fits the plastic region of a tensile curve to extract n.
How the Value Is Obtained
A standard tensile test is run on sheet, and the uniform plastic portion of the true stress-strain curve is fitted to a power law. Accurate strain measurement over the fitting range is essential, so a suitable extensometer and clean data are required.
Preparing Specimens
Flat sheet specimens with clean edges and accurate width keep the result reliable. To set up n-value testing, request a quote.
Reading the Designation
Cited with a year suffix such as ASTM E646-YY. Confirm the edition and the strain range for the fit.
Related Standards
ISO 10275 is the ISO n-value method for flat metal products, and ASTM E8/E8M is the underlying tensile method.
Request a Quote
Setting up n-value testing on sheet metal? Request a quote and our team will help you build a system matched to your sheet gauge and strain measurement.
TensileMill CNC products for ASTM E646
Our specimen-preparation systems and testing equipment compatible with ASTM E646:
TensileMill CNC MICRO – Precision Flat Tensile & Impact Micro Machine
MICRO – Precision Flat Tensile & Impact Sample Preparation
TensileTurn CNC – Industrial Upgrade – Round Tensile Sample Preparation Machine
Industrial Upgrade – Round Tensile Sample Preparation
Electro Mechanical Universal Testing System 5 kN / 50 kN with Precision Load Cell
Electro-Mechanical UTM · 5 kN / 50 kN with Precision Load Cell
Bring ASTM E646 testing in-house with TensileMill CNC
TensileMill CNC designs and builds the systems labs use for standards-based mechanical testing. Depending on your specimens, that can include universal testing machines, wedge or pneumatic grips, and flat and round specimen-preparation systems. Tell us your materials, specimen forms, and required test sections, and our team will match the right configuration.