42918 2017 eng 1 7 article Taylor & Francis 0 -- -- -- Using the novel optical measurement technique together with the optical flow algorithm, a twodimensional deformation analysis during welding has been conducted. This technique provides for the first time a measurement of the strain field locally in the immediate vicinity of the assumed solidification front. The described procedure of the opticalmeasurement allows to determine the real martial-dependent values of critical strain and strain rate characterising transition to the hot cracking during laser welding processes. The local critical strain that obtained in the assumed solidification showed that the local critical strain decreases as the strain rate increases. Moreover, this phenomenon has also been shown with results from the CTW-test, since the global strain decreases with an increase in the external strain rate. Science and Technology of Welding and Joining 10.1080/13621718.2017.1367550 1362-1718 Nasim Bakir Andrey Gumenyuk Michael Rethmeier eng uncontrolled Novel optical measurement eng uncontrolled Local critical strain eng uncontrolled Solidification cracking eng uncontrolled Laser beam Welding Ingenieurwissenschaften und zugeordnete Tätigkeiten Verlagsliteratur Datei im Netzwerk der BAM verfügbar ("Closed Access")