Formulation of effective thickness for predicting CTOD value of heavy thickness plates using reduced thickness CTOD specimens

Abstract

Demand for heavy thickness plate is increasing in offshore structure application and fracture toughness represented by CTOD is one of the most important properties for these heavy thickness plate. CTOD tests shall be conducted as full thickness of the material but it takes a lot of time and cost, especially with the thickness exceeds 100 mm. It is important to estimate the CTOD of full thickness plate using reduced thickness CTOD tests to accelerate material development in the laboratory. As a conventional estimating method for full thickness CTOD using the reduced thickness CTOD test, only the difference of crack driving force between full thickness and reduced thickness specimens have been considered. However, it is necessary to consider crack driving force in plate thickness direction for full thickness and reduced thickness specimens. As the first step, the influence of parameters on effective thickness considering crack driving force in plate thickness direction for the base metal is investigated in this study. Finally, the formulation of effective thickness is proposed on the base of the influential parameters.

Keywords:

• CTOD
• heavy thickness plate
• reduce thickness CTOD test
• crack driving force
• effective thickness