Kinetics and Microstructural Control

Welding and weld cooling rate

· When materials are joined by welding the thermal history of the weld is not well controlled and may give rise to a brittle junction between the two components.
· The diagram indicates the structure of a weld region, the heat affected zone.
· Composition changes, contamination with hydrogen or nitrogen from the air, and microstructure changes due to the cooling rate all occur.

From: Ashby & Jones, "Engineering Materials," Pergamon (1986)