Fatigue Crack Initiation from Defects at Weld Toes in Steel

J,L. OTEGUI; H. KERR; D. BURNS; U. MOHAUPT

INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 1989 vol. 38 p. 385 - 417

0308-0161

The mechanisms of fatigueinitiation and microcrack growth at the toes of good quality manual and automatic T-plate welded joints in steel were investigated, using a compliance method to measure crack depth and closure levels, and three-stage ink staining, replica techniques and SEM microscopy to monitor crack growth. Minor undercuts, slag inclusions and surface spatter at the weldtoes were detected as fatigueinitiation sites in manual welds. Fatigueinitiation in automatic welds was mainly associated with undercut-type defects. Details of their propagation and coalescence early in the fatigue process are documented. Delayed microcrack coalescence in the case of manual welds appears to be related to the more irregular toes of the manual welds, when compared to their automatic counterparts