Microstructure and mechanical behavior of a low-density Fe-12Mn-9Al-1.2C steel prepared using centrifugal casting under near-rapid solidification

It is vital for emission reduction and energy saving to lighten the weight of automobile. Low-density Fe-Mn-Al-C steels with high strength and excellent ductility have become a promising type of material in the automotive industry. Thus, a new approach was proposed by using centrifugal casting to produce the low-density Fe-12Mn-9Al-1.2C steel with high performance under near-rapid solidification in a near-net shape. The produced steel strips, with a thickness of 2.5mm and a density of 6.89g/cm(3), were examined for their microstructures and mechanical properties. The results showed that mechanical properties of as-cast steel strip reached 1182MPa in ultimate tensile strength and 28.1% in total elongation. Aging treatment at 400 or 600 degrees C for 3h enhanced tensile strength of the steel strips, while aging at 800 degrees C dramatically decreased its elongation. Moreover, Young's modulus of the steel strip improved with the increment of aging temperature. The relationship between the mechanical properties and the microstructures was discussed. The results demonstrated that advanced low-density steels with promising mechanical properties could be directly produced from liquid by this simple process.