CTOD (Crack Tip Opening Displacement) Test

About CTOD Test

CTOD testing image CTOD testing image

When material with a defect is loaded, a crack will propagate rapidly originating from the defect, resulting in fracture at a certain temperature range (unstable fracture). CTOD test is one of test methods to determine fracture toughness (fracture resistance) of a material with a crack, and a test to determine crack tip opening displacement to generate unstable fracture (limit CTOD value). It is generally performed by loading a test piece on a 3-point bending system as shown in right figure.

JFE-TEC can provide a wide range of test specimen thickness from 6 mm to 100 mm, and accommodate test temperature from +200 ℃ to -196 ℃ (depending on the test specimen size).

Outline of Test

Test Procedure

Preparation of test piece → Introduction of a fatigue precrack → CTOD testing → Appearance of fracture surface → Measurement of fracture surface → Evaluation → Preparation of report

We can provide one-stop service for the above procedure from test piece preparation to reporting.

Corresponding Standards

BS 7448 :
Fracture mechanics toughness tests
ISO 12135 :
Metallic materials - Unified method of test for the determination of quasistatic fracture toughness
ASTM E 1820 :
Standard Test Method for Measurement of Fracture Toughness
WES 1108 :
Standard Test Method for Crack Tip Opening Displacement (CTOD) Fracture Toughness Measurement

Equipment To Be Used

Autograph AG-250kNXplus (loading capacity: 250 kN) made by Shimadzu

Universal test machine (loading capacity: 500 kN) made by Shimadzu

Universal test machine (loading capacity: 2,000 kN) made by Tokyo Koki

Testing scenes (250 kN test machine)

Example of test

CTOD Test of Weld Heat Affected Zone (HAZ)

The following is a case example of the procedure: a notch was introduced at weld HAZ and CTOD test was performed.

Determination of notch location Determination of notch location
Test piece after notch preparation Test piece after notch preparation
Load-opening displacement diagram obtained by CTOD test Fracture surface of test piece after the test
Load-opening displacement diagram
obtained by CTOD test
Fracture surface of test piece after the test

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