Coarse Grain Heat Affected Zone (CGHAZ)

The region of the heat-affected zone nearest the weld fusion line that reaches the highest peak temperature during welding, close to the melting point, causing pronounced grain growth compared with the rest of the heat-affected zone. Its coarse grain structure often gives it lower toughness than other regions of the weld and heat-affected zone, making it a frequent focus of weld toughness testing.