Optimization of silicon and aluminum content for improving properties of the heat-affected zone metal of high-hardness Cr–Ni–Mo steels

Keywords

Cr–Ni–Mo high-hardness steels, optimization of Si and Al content, thickness of protective structural elements, heat-affected zone metal, microstructure.

Cite as

Kushnarova O. S., Kostin V. А., Poznyakov V. D., Alekseienko I. I., Alekseienko T. O., and Berdnikova O. M. Optimization of silicon and aluminum content for improving properties of the heat-affected zone metal of high-hardness Cr–Ni–Mo steels. Physicochemical Mechanics of Materials. 2026. 62(2), 098-106.

https://doi.org/10.15407/pcmm2026.02.098

Abstract

The choice of the Cr–Ni–Mo alloying system for high (450–550 HB) and ultra-high (> 600 HB) hardness steels, taking into account the influence of silicon (Si) and aluminum (Al) on the properties depending on the thickness of the protective elements of the structure is substantiated. To decrease steel intensity of the protection system against high-energy impacts, it is sufficient to use plates with a thickness of 20 mm and the maximum silicon content in the steel is of priority to ensure its surface hardness. It is shown that for t < 20 mm, an increased Si content is advisable to ensure high surface hardness, while for t > 20 mm the through-hardenability and impact toughness are determining factors. This is achieved by an increased Al content due to the grain refinement of austenite. The influence of the Al/Si content ratio on the combination of mechanical properties and microstructure stability, in particular in the heat-affected zone of welded joints, is analyzed. The need for a differentiated approach to choosing an alloying system and optimizing the Al/Si content ratio in accordance with the thickness of the protective structural elements and expected failure mechanisms is substantiated.

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