Microstructural Evaluation and Mechanical Properties of 0.75% Vanadium-Alloyed Spheroidal Graphite Cast Iron

Abstract

Spheroidal graphite cast irons (SGCIs) have been widely used in automotive and energy industries owing to their unique microstructures consisting of graphite nodules in ferritic, pearlitic, or ferritic/pearlitic matrices. Alloying elements can be added to improve the mechanical strength of the SGCIs by changing the amount, size, volume, and distribution of the microstructural components. In this study, GGG40, also known as EN-GJS-400-15, grade spheroidal graphite cast iron was alloyed with 0.75% vanadium in an induction furnace, and its microstructural evolution and mechanical properties were investigated compared to the unalloyed commercial alloy. Both unalloyed and 0.75% V-alloyed ductile iron specimens fabricated by sand mold casting were examined by a light optical microscope equipped with image analysis software, a universal tensile test machine, and a Brinell hardness tester. The alteration in the volume, nodularity, count, size, and distribution of graphite, and the alteration in the ferrite/pearlite ratio, hardness, and tensile test results were discussed as a function of V content.