HN
The finished product from a manufacturer (the pipe or fitting mill), is typically traceable to a Heat Number (steel mill identification). A heat typically identifies material produced in the steel mill from one single melt, and the number will be assigned in the steel mill. Chemical analysis is usually reported on a heat basis. Parts of a same heat have the same chemistry.
HAZ
HAZ is an abbreviation of Heat-Affected Zone.
Cutting processes that use intense heat, like oxyfuel cutting and plasma arc cutting, produce thermal effects near the edge of the cut that lead to microstructural and metallurgical changes in the metal. The portion of a metal work-piece that has been so altered by heat is termed the heat-affected zone or HAZ. All thermal cutting processes create an HAZ in the cut metal.
