Macrographs and Micrographs

In metallurgy, macrography and micrography are analysis techniques used to study the structure of metals at different levels of detail.

Macrography

Macrography consists of examining a sample with the naked eye or at low magnifications (usually up to 10–25x), often using a stereomicroscope.

• Purpose: To provide an overall view of the material structure and macroscopic defects.
• What it detects: Forging flow lines, porosity, surface cracks, heat-affected zones in welds, and lack of fusion.
• Procedure: The sample is cut, polished, and subjected to a “chemical etching” (macro-etching) process using acidic reagents to highlight the structure.

Micrography

Micrography is the analysis of the internal structure at high magnifications (above 50–100x), carried out using optical or electron microscopes (SEM).

• Purpose: To study the microstructure, crystalline phases, and material properties at a microscopic level.
• What it detects: Size and shape of crystalline grains, non-metallic inclusions, precipitates, micro-cracks, and structural constituents (such as ferrite, pearlite, etc.).