Development of ultra-high strength carbide-free bainitic cast steels

ABSTRACT High-silicon cast steels and proper heat treatment cycles were designed in order to obtain carbide-free bainitic microstructures. The design process allowed to obtain the desired microstructures after heat treatment cycles compatible with industrial practices and using low amounts of inexpensive alloying elements. The different chemical compositions and austempering temperatures tested resulted in ultra-high-strength steels showing remarkably total elongations. The obtained tensile properties satisfy the minimum requirements specified for AHSS in ASTM A1088 standard, and also the requirements for high-strength cast steels stated in ASTM A148. Moreover, many microstructures developed in this work reach the tensile performance of the very expensive maraging steels.