A CRACK-ARREST TEST USING A TOUGHNESS GRADIENT STEEL PLATE

A crack arrest test was carried out using a toughness gradient steel p late with three layers to study the concept of crack arrest toughness. Four-point bending load with thermal shock was applied to the large f lat plate specimen with a surface crack. Five crack initiations and ar rests were observed during the test and the propagated crack bifurcate d. Finally, cracks were arrested at the boundary of the first and the second layer, except for a small segment of the crack The first crack initiation took place slightly higher than the lower bound of K-Ic dat a obtained by ITCT specimens. That is, the K-IC concept for brittle cr ack initiation was verified for heavy section steel plates. The first crack arrest took place within the scatter band of K-Ia and K-Id data for the first layer. That is, the K-Ia concept appears applicable for crack arrest of a short crack jump.