The effect of Al and C additions on the mechanical properties of spray formed lightweight steels

Abstract

Lightweight steels are advanced materials that are being developed with primary focus on the automotive industry, with the main purpose of reducing the structural weight of cars. The major feature of these materials is the low density due to the addition of elements such as Mn and Al. The main studies involving these steels are related to the evaluation of mechanical properties, since some compositions present the effects of Transformation Induced Plasticity (TRIP) and Twinning Induced Plasticity (TWIP). The main studied compositions correspond to variations of Fe-Mn-Al-C system, wherein alloying elements and the processing route interfere directly the final microstructure, consequently affecting the mechanical properties. The objective of this thesis is to evaluate the effect of Al and C additions on high-manganese steels in order to observe the effects that these additions will bring on the mechanical properties. For this study, it is proposed to study nine systems varying C and Al content, the effect of carbon will be made through comparison of materials with the same Stacking Fault Energy (SFE). The billets will be manufactured by spray forming and subsequently submitted to hot and cold rolling until the thickness of a thin sheet. The mechanical properties will be evaluated and microstructural analysis will be performed at different deformation stages through interruption of the test. The use of spray forming is justified due to the characteristics of the processing bringing a very uniform microstructure directly from the liquid (these alloys has a high tendency of segregation due to the high alloying elements and these technique tends to lower this problem). (AU)