Metallographic Analysis of Kinetically Activated Bainite (KAB) Welds

Abstract

Weldability of kinetically activated bainite steels with the process of activated tungsten inert gas welding was evaluated by means of mechanical testing and metallographic techniques. The latter were used to identify which phases formed and to determine their volume fractions as well as formation mechanisms. Based on this information, correlations were established between the welding parameters and the observed metallurgical phenomena. Particular emphasis was put on the morphology and the amount of retained austenite and the local formation of martensite. All tests were performed without preheating or post weld heat treatment of the high-carbon steel.