Mechanical properties of a carbide-free bainitic cast steel with dispersed free ferrite

Abstract

A high silicon, medium carbon cast steel was designed and heat-treated in order to develop microstructures composed of carbide-free bainite and small amounts of free ferrite, with the aim of obtaining high strength cast steels with improved ductility. Because of microsegregation, it was observed that ferrite present in partially austenitised samples is mostly present at the highly alloyed zones, creating an interconnected network even for low proportions of this phase. Despite the coarse solidification structure and marked microsegregation in the cast steel, the mechanical properties obtained for both fully bainitic and bainitic-ferritic microstructures largely satisfy the minimum standard requirements for high strength cast steels and are similar to those reported for wrought steels of similar microstructures.

Effect of Microsegregation and Bainitic Reaction Temperature on the Microstructure and Mechanical Properties of a High-Carbon and High-Silicon Cast Steel

“…A study carried out on a carbide-free bainitic cast steel with chemical composition 0.54C-2.01Si-0.64Mn-0.50Cr (wt.%) showed a UTS of 1610 MPa, YS 1446 MPa, and TE of 12.3%. These mechanical properties obtained in this cast steel are remarkable, since they combine ultra-high strength and medium ductility [78]. On the other hand, the hardness, UTS, YS, and TE of a family of steels with a combination of different chemical compositions and heat treatment parameters allowed obtaining microstructures with hardness ranging from 40 to 55 HRC, UTS ranging from 1312 to1979 MPa, YS from 1114 to 1799 MPa, and TE values ranging from 0.4% to 17.8% [79].…”