title: Initiation and growth kinetics of solidification cracking during welding of steel.
abstract: Solidification cracking is a key phenomenon associated with defect formation during welding. To elucidate the failure mechanisms, solidification cracking during arc welding of steel are investigated in situ with high-speed, high-energy synchrotron X-ray radiography. Damage initiates at relatively low true strain of about 3.1% in the form of micro-cavities at the weld subsurface where peak volumetric strain and triaxiality are localised. The initial micro-cavities, with sizes from 10 × 10-6m to 27 × 10-6m, are mostly formed in isolation as revealed by synchrotron X-ray micro-tomography. The growth of micro-cavities is driven by increasing strain induced to the solidifying steel. Cavities grow through coalescence of micro-cavities to form micro-cracks first and then through the propagation of micro-cracks. Cracks propagate from the core of the weld towards the free surface along the solidifying grain boundaries at a speed of 2-3 × 10-3m s-1.
authors.affiliation: Department of Engineering, University of Leicester, LE1 7RH, UK.
authors.forename: L
authors.initials: L
authors.lastname: Aucott
authors.affiliation: Department of Engineering Science, Oxford University, OX1 3PJ, UK.
authors.forename: D
authors.initials: D
authors.lastname: Huang
authors.affiliation: Department of Engineering, University of Leicester, LE1 7RH, UK.
authors.forename: H B
authors.initials: HB
authors.lastname: Dong
authors.affiliation: Department of Engineering, University of Leicester, LE1 7RH, UK.|Tata Steel, Research &Development, Swinden Technology Centre, Rotherham, S60 3AR, UK.
authors.forename: S W
authors.initials: SW
authors.lastname: Wen
authors.affiliation: Tata Steel, Research &Development, Swinden Technology Centre, Rotherham, S60 3AR, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Marsden
authors.affiliation: European Synchrotron Radiation Facility, BP220, F-38043 Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Rack
authors.affiliation: Department of Engineering Science, Oxford University, OX1 3PJ, UK.
authors.forename: A C F
authors.initials: AC
authors.lastname: Cocks