Hot Ductility Behavior in the Weld Heat-Affected Zone of Austenitic Fe-Mn-Al-C Lightweight Steels and the Effects of Alloying Elements

Abstract

Three austenitic Fe-Mn-Al-C alloys containing different Mo, Cr, and Si contents were prepared to evaluate the effects of alloying elements on the hot ductility behavior of the weld heat-affected zone (HAZ) of austenitic light-weight steels. HAZ simulations and hot tension tests were performed using a Gleeble simulator. The hot tension tests were conducted at 500 - 1220 ℃ during on-heating and on-cooling cycles. The results showed that the hot ductility significantly varied according to the behavior of κ-carbide precipitation with a decrease in temperature. The tensile ductility values of all the alloys were high at elevated temperatures above 1000 ℃ because of dynamic recrystallization. At intermediate temperatures of 700 - 900 ℃, significant ductility drops occurred in all alloys because κ-carbide precipitation, and the addition of Si resulted in more significant of ductility loss than in Cr or Mo added alloys. These different effects occurred because Mo and Cr suppressed κ-carbide precipitation, whersase Si promoted it. Ductility was recovered at low temperatures of approximately 500 ℃.