ASTM E8/E8M-Standard Test Methods for Tension Testing of Metallic Materials

Standard Test Methods for Tension Testing of Metallic Materials (Inch and Metric Versions)

This specification covers the tensile testing procedures for metallic materials to determine properties such as:

Yield Strength

Ultimate Tensile Strength

Elongation

Reduction of Area

It applies to specimens in the form of sheet, plate, bar, wire, tube, and pipe, across various metals including titanium, steel, aluminum, and nickel alloys.

1. Purpose

ASTM E8/E8M provides the standardized methodology and specimen dimensions for testing metals in tension to determine their mechanical behavior under load.

2. Specimen Types and Dimensions

The standard allows for different specimen geometries depending on product form and thickness.

Common Specimen Types:

D = diameter of the round specimen; gauge length may vary by material size and configuration.

3. Key Mechanical Properties Measured

Yield Strength  Stress at which material begins to deform plastically (typically 0.2% offset method)

Ultimate Tensile Strength (UTS)-Maximum stress the material can withstand

Elongation (%)-Percent increase in length before fracture

Reduction of Area (%)-Change in cross-sectional area at fracture

4. Test Procedure Summary

Prepare Specimen-Per dimensions specified in standard (flat or round).

Mount in Tensile Testing Machine-Securely grip ends.

Apply Axial Load at Constant Rate-Typically strain rate-controlled.

Record Load vs. Extension-Using extensometers or machine crosshead.

Calculate Properties-Based on original cross-section and elongation.

5. Testing Equipment

Tensile Testing Machine-Calibrated and capable of controlled loading.

Extensometer-Measures elongation with high precision.

Grips/Fixtures-Must hold specimen securely without slippage.

6. Tolerances and Accuracy

Alignment: Axial alignment must minimize bending stress.

Strain rate control: Required for reproducible results.

Calibration: Machines and extensometers must be regularly verified.

7. Reporting Requirements

Test reports must include:

Material specification and heat number

Specimen type and dimensions

Test temperature (if not room temperature)

Yield strength (MPa or ksi)

Ultimate tensile strength

Elongation (%)

Reduction of area (if applicable)

Any deviations from standard procedure

8. E8 vs E8M-Inch vs Metric

ASTM E8: Inch-pound units (ksi, inches)

ASTM E8M: SI units (MPa, mm)

The procedures are technically identical except for unit systems.

9. Applications

Quality control and mill certification of metals

Verification of mechanical properties in:

Titanium alloys (e.g., ASTM B348, B265)

Stainless steels

Nickel-based alloys

Aluminum products

10. Standards Related to ASTM E8/E8M

ASTM E4-Calibration of testing machines

ASTM A370-Mechanical testing of steel products

ASTM B348-Titanium bar (often tested to E8)

ASTM B265-Titanium plate/sheet (often tested to E8)