Structure, deformation behavior under static tension and impact toughness of 09Mn2Si steel subjected to helical rolling

The structure and mechanical properties of ductile ferrite-pearlitic steel 09Mn2Si after helical rolling (HR) were studied. It was shown that during the HR with a gradual temperature decrease (within the range of 850-500 °C) a finely dispersed structure forms in the surface layer up to ~ 1 mm deep. The latter indicated on the development of severe plastic deformation there while in the lower layers a strongly textured “lamellar” mesostructure was formed. It consisted of elongated ferrite grains oriented along the rod axis (along the HR direction). The largest hardening was registered in the surface layer with a thickness of ~3 mm; the lowest one - in the core of the rod. The results of the tensile test have shown that HR leads to an increase in tensile strength and a decrease in elongation at break. It was found that a yield tooth and plateau are retained on the loading diagrams of the samples subjected to the HR. The duration of the latter increased by ~ 2 times compared to the as-received steel. Impact loading experiments have shown that the HR results in increasing the KCV by an ~ 10-25 % while at subzero temperatures the difference reached 60 %.

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