Being one of the most important alloying elements, manganese (Mn) is applied in all steels for several reasons, e.g. for avoiding hot shortness, for controlling austenite decomposition during cooling stage, and for solid solution hardening. More recently, due to its significant influence on stacking-fault energy, Mn controls the exploitation of advanced strengthening mechanisms, such as transformation-induced plasticity (TRIP), twinning-induced plasticity (TWIP), and micro-band-induced plasticity (MBIP) in modern advanced high strength steels (AHSS). For this reason, high Mn TWIP steels and density reduced high Mn steels, belonging to the second generation AHSS, as well as medium Mn and lean medium Mn steels, being a candidate for the third generation AHSS, have become a subject of intensive research and development. Recently, due to its strong delay of diffusion controlled phase transformations, medium Mn steels have also been considered for air hardening steels in forging applications. Apart from this, Mn can also be used for the austenite stabilization instead of expensive Ni in austenitic high N stainless steels. Mn significantly increases N solubility, which fosters solid solution strengthening and pitting corrosion resistance.

Besides already mentioned advanced strengthening mechanisms in mainly multiphase microstructures, undesirable plastic instabilities, such as yield point elongation and dynamic strain aging, might occur in the given steel grades. This makes their application even more difficult and the researchers must understand the underlying phenomena in order to avoid the occurrence of these detrimental effects in case of anticipated products. Since the final microstructure of these steels usually contains austenite, with a low diffusibility but high solubility of hydrogen, which mostly undergoes martensitic transformation or twinning during straining, the topic of hydrogen embrittlement becomes of paramount importance during their development. In summary, all these often ultrafine-grained microstructures, wherein a variety of advanced physically based mechanisms can be activated, require the application of cutting-edge observation techniques supported by extensive modelling. This significantly contributes to precise control of their final well-balanced microstructures and excellent mechanical properties.

The HMnS2022, organized by voestalpine, the University of Applied Sciences in Wels, and ASMET, was the fifth international conference covering all scientific and technical aspects of high Mn, medium Mn, and other Mn containing high alloy steels suitable for the application in the automotive industry and transportation, oil and gas and offshore applications and many others. After the success of the previous HMnS conferences in Seoul (2011), Aachen (2014), Chengdu (2016), and again Aachen (2019), the HMnS2022 was held in Linz, Austria. The conference brought together more than 100 international scientists and engineers from over 20 countries with more than 70 contributions to discuss the understanding of the underlying physical phenomena and to give possible answers to relevant technical challenges of the selected steel grades. Some papers from this conference are collected in the present special issue of BHM.

We wish you a pleasant reading,

Prof. Reinhold Schneider and Prof. Daniel Krizan

HMnS2022 conference chairs and guest editors of the special issue