DEPTH PREDICTION METHOD OF CRACK CAUSED BY DELAYED FRACTURE AT STEEL PLATE CUT END

摘要

PROBLEM TO BE SOLVED: To provide a method capable of speedily and accurately predicting the depth of a crack caused by a delayed fracture at a cut end of a steel plate.;SOLUTION: Crystal orientation data in a non-strain part and cut end is obtained by applying EBSP measurement to a plate thickness cross section orthogonal to a cut end surface of a steel plate (S1 and S2). Then, an average KAM value K0 in the non-strain part is calculated on the basis of the crystal orientation data in the non-strain part (S3). While, an average KAM value K1 in a predetermined measurement region is calculated at each certain distance from the cut end surface toward its opposite end surface on the basis of the crystal orientation data at the cut end (S4). The average KAM value K0 in the non-strain part is compared with the average KAM value K1 in the predetermined measurement region at each certain distance at the cut end, and, of a predetermined region satisfying the condition that K1 is larger than K0 by [measurement interval (unit: μm)×2 of the crystal orientation data]° or more, the distance from the cut end surface to the farthest predetermined measurement region is determined to be the crack depth (S5).;SELECTED DRAWING: Figure 1;COPYRIGHT: (C)2016,JPO&INPIT