Three generations of advanced high strength steels (AHSS) have attracted considerable attention due to their excellent mechanical properties and relatively low cost. While there has been extensive research on the basic mechanical properties of AHSS, the impact energy absorption capacity, a critical property for ensuring passenger safety, has not been systematically investigated. In addition, the absence of standardized impact testing protocols for materials or structures hinders the comparison of results across different studies. The present review aims to provide a comparative analysis of the impact performance of thin-walled structures and sheet specimens made from the three generations of AHSS. First, an introduction to the background of AHSS is presented. Widely used experimental techniques and specimen geometries are then reviewed. This is followed by a detailed review of recent relevant studies on the first, second, and third generations of AHSS. Emphasis is placed on investigating the influence of microstructure on impact performance and the underlying mechanisms governing high-strain-rate plastic deformation under impact loading. Various strategies to improve the impact performance of AHSS are also discussed.

The article focuses on the effect of alloying and microstructure on formability of advanced high strength steels (AHSSs) processed via quenching and partitioning (Q&P). Three different Q&P steels with different combination of alloying elements and volume fraction of retained austenite are subjected to uniaxial tensile and Nakajima testing. Tensile mechanical properties are determined, and the forming limit diagrams (FLDs) are plotted. Microstructure of the tested samples is analyzed, and dramatic reduction of retained austenite fraction is detected. It is demonstrated that all steels are able to accumulate much higher amount of plastic strain when tested using Nakajima method. The observed phenomenon is related to the multiaxial stress state and strain gradients through the sheet thickness resulting in a fast transformation of retained austenite, as well as the ability of the tempered martensitic matrix to accumulate plastic strain. Surprisingly, a Q&P steel with the highest volume fraction of retained austenite and highest tensile ductility shows the lowest formability among studied grades. The latter observation is related to the highest sum of fractions of initial fresh martensite and stress/strain induced martensite promoting formation of microcracks. Their role and ability of tempered martensitic matrix to accumulate plastic deformation during forming of Q&P steels is discussed.