1. Two levels of inspection

    The metallographic section inspection of welded joints is usually carried out at two levels of inspection

    Macro:

    Use a stereo microscope to achieve a magnification of up to 50 times.

    Microscopic inspection is usually carried out on non embedded sections passing through welded joints and involves cutting and coarse/fine grinding techniques. The obtained smoothness is sufficient for etching, and then the macroscopic characteristics of the welded joint are inspected, some of which are as follows:

    Weld geometry

    Number and size of weld beads

    Depth of penetration layer

    Scope of HAZ (Heat Affected Zone)

    Surface defects such as cracks, grooves, excessive thickness of filler metal, convex surfaces, and weld toe angles.

    Internal defects such as cracks, holes, metal inclusions, melting defects, welding penetration defects, and slag.

    Joint geometry such as weld root gaps, weld root surfaces, bevel angles, and misalignment.

    Related equipment: Leica body microscope: S9i, SAPO, M125/165/205

    Micro:

    Use a Leica microscope to achieve inspection at a large magnification (up to 1000 times).

    For micro inspection techniques and hardness cross-cutting, a polished and optically flat surface needs to be provided. Conduct microscopic inspections to study welding defects and microstructure characteristics, such as voids (pores, cavities, microcracks)

    Special phase (in stainless steel) Σ Phase)

    Particle size/- structure

    welded structure

    separate

    HAZ and base structure

    Related equipment: Leica metallographic microscope DM2700, DM4M, DM6M