A review of the effects of chemical and phase segregation on the mechanical behaviour of multi-phase steels

TL;DR

This review discusses how chemical and phase segregation influence the microstructure and mechanical behavior of multi-phase steels, emphasizing the origins of segregation, its effects on properties, and microstructural modeling for improved production.

Contribution

It provides a comprehensive overview of segregation effects in multi-phase steels and explores microstructural modeling techniques to mitigate banding and improve mechanical performance.

Findings

Segregation during casting leads to banding and affects mechanical properties.

Microstructural models can help tailor production to reduce segregation effects.

Experimental techniques elucidate the structure-property relationships in segregated steels.

Abstract

In the drive towards higher strength alloys, a diverse range of alloying elements is employed to enhance their strength and ductility. Limited solid solubility of these elements in steel leads to segregation during casting which affects the entire down-stream processing and eventually the mechanical properties of the finished product. Although it is thought that the presence of continuous bands lead to premature failure, it has not been possible to verify this link. This poses as increasingly greater risk for higher alloyed, higher strength steels which are prone to centre-line segregation: it is thus vital to be able to predict the mechanical behaviour of multi-phase (MP) steels under loading. This review covers the microstructure and properties of galvanised advanced high strength steels with particular emphasis to their use in automotive applications. In order to understand the origins of banding, the origins of segregation of alloying elements during casting and partitioning in the solid state will be discussed along with the effects on the mechanical behaviour and damage evolution under (tensile) loading. Attention will also be paid to the application of microstructural models in tailoring the production process to enable suppression of the effects of segregation upon banding. Finally, the theory and application of the experimental techniques used in this work to elucidate the structure and properties will be examined.