It is the examination of the etched or non-etched sample with a microscope at 50 to 500 times magnification.
Microscopic experiments are used to reveal microscopic properties by examining the cross-section of the welded joint. The purpose of microscopic examination is to examine hot cracks, cold cracks, lamellar tearing, voids, melt deficiency, solidification structure and grain structure, etc. to reveal the features.
TS EN ISO 17639: Destructive Inspection of Welds in Metallic Materials – Macroscopic and Microscopic Inspection of Welds