Heat Affected Zone
The band beside a weld whose properties change with the welding heat — in armour steel, it softens.
Armour steel owes its hardness to quenching and tempering, and welding undoes that locally. The softened band cannot be restored by post weld heat treatment without ruining the rest of the plate, so armour design keeps welds off the primary strike face, controls interpass temperature and uses austenitic consumables that tolerate the mismatch. It is the single most common reason a fabricated armour structure underperforms the plate it is made from.
Related terms
Where this applies
fabricated-assemblies, armour-ballistic-materials
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