1. Macrographic and micrographic observations

1.1 Sample collection

In most cases, macroscopic and/or microscopic observations are made transversely (perpendicular to the welding axis) to the weld bead. The sample size must be large enough transversely to contain not only the molten zone (ZF) of the weld bead (in the case of fusion welding), but also the entire heat-affected zone (ZAT) and a portion of the base metal (MB). Sampling techniques must not thermally alter the weld bead. In most cases, samples are taken by fluid sawing, to avoid overheating the sample. In the case of sampling by thermal cutting (flame, plasma, etc.) for massive parts or on site, for example, cuts must be made sufficiently far from the weld bead (more than 8 mm from the zone affected by the temperature) so as not to thermally reallocate the weld bead....