Direct observations of the formation and growth of austenite from pearlite and allotriomorphic ferrite in a C-Mn steel arc weld

The formation and homogenization of austenite from ferrite and pearlite are directly observed in the heat affected zone of a 1045 C-Mn steel arc weld. With rapid heating, cementite does not completely dissolve before the base metal ferrite is transformed, and a second austenite constituent forms. These two austenite constituents exist up to 1400 °C before a single homogeneous austenite phase is produced.