HAZ : Heat affected zone. The area around a weld or other area in the steel that has been modified by heat and, as a result, is more subject to some forms of corrosion.
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}