Microstructure–Mechanical Properties Correlation in Ultrafine Grained Steels Processed by Large Strain Warm Deformation

Abstract

Ultrafine-grained steels with grain size of about 1 μm offer the prospect of high strength coupled with high toughness among conventional steel compositions and are attracting the attention of researchers worldwide. Application of these ultrafine grained steels to the fabrication of potential engineering structures demand extensive study of their mechanical properties and reasons for the improvement in order to get detailed insight into their behaviour under operating conditions. While there are many studies on the development of ultrafine grained microstructures per se, fewer studies were reported on the more important aspect of evaluating their mechanical properties. This is to verify the basic assumption that the microstructural refinement at bulk level indeed improves the properties offering the prospect of a realistic replacement of the existing conventional steels in the near future. This review article attempts to present a comprehensive picture on the microstructure-mechanical properties correlation of ultrafine grained steels fabricated by large strain warm deformation and reasons behind the improved properties from a micromechanics point of view.