Index of acronyms 

HAZHeat-Affected Zone – is the region of parent material immediately next to a weld that is not actually melted during the welding operation, but in which the properties and microstructure of the material are altered by the heat input. The extent of changes to the properties depends on the weld filler metal, the parent material and the heat input.

The changes in properties in the HAZ can make this region susceptible to cracking, for example hydrogen cracking or reheat cracking, and also to corrosion, for example weld decay in stainless steel due to intergranular corrosion in the HAZ.

Conventional NDT techniques can be applied to detect defects in the HAZ, depending on whether they are surface breaking on an accessible surface, on an inaccessible surface or embedded.

For more information on HAZ see:
J R Davis, K Ferjutz and N D Wheaton, ASM Handbook Volume 6: Welding, Brazing and Soldering, ASM International, 1993.

What the hec?! articles are not intended to be the definitive account on the topic or acronym in question. Readers’ comments and contributions are welcomed. Email: ndtnews@bindt.org