Quantitative evaluation of solidification brittleness of weld metal during solidification by in-situ observation and measurement (report V). Correlation between critical strain rate and critical deformation rate required for solidification crack initiation

Behaviors of strain rate near solidification front and mean deformation rate of specimen have been investigated using tensile cracking test with restraint-relaxation U-form hot cracking device combined direct observation technique MISO for stainless steels. The behavior of strain rate measured by MISO technique with lapse time after start of welding corresponded to that of mean deformation rate measured by strain gauge method. Critical deformation rate required for crack initiation was appropriate for comparison of the crack susceptibilities among materials as critical strain rate required for crack initiation.