1986 Volume 4 Issue 1 Pages 182-186
Crack opening displacement (COD) testing is widely used to determine the fracture toughness of steel materials. However, COD tseting of thick weldments involves the problem of a non-uniform shape of fatigue precracking through the thickness due to the influence of welding residual stress. In this study, first, the residual stress distribution in a thick weld metal COD specimen was measured to clarify the cause of the irregular fatigue crack front. Then, initial machined notches of various shapes were tested to select suitable ones which would not affect the material toughness and would not have a non-uniform shape. As a result it was found that a partial arc notch and partial drill hole notch meet the above requirements.