Heat Affected Zone (HAZ) 1 : That portion of the base metal which has not been melted, but whose mechanical properties microstructure has been altered by the heat of welding or cutting. (Spec 6A, Spec 16).
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}