Online Lecture by prof. Tadashi Furuhara

Strengthening of low-alloy steels by controlling nanoscale precipitation

Institute for Materials Research, Tohoku University, Japan

Title:
Strengthening of low-alloy steels by controlling nanoscale precipitation

Abstract:
Precipitation strengthening is one of the most important mechanisms to achieve high strength of metallic materials. In advanced high strength sheet steels, interphase precipitation of alloy carbide during ferrite transformation is utilized with microalloying of strong carbide forming elements. For surface hardening of low-alloy steels for machinery by nitriding to obtain good wear resistance and fatigue-bearing properties, fine dispersion of alloy nitride is essential.

In this lecture, fundamental principles for controlling alloy carbide/nitride precipitation are discussed. Particular, the importance of strongly attractive elemental interactions between interstitial (i) and substitutional (s) alloying elements, which causes metastable atomic clustering governed by ‘spinodal ordering’ as a precursor is emphasized for achieving finer particle dispersion of stable carbide/nitride phase.

This leads to a novel concept of ‘interstitial sublattice engineering’ for designing high strength steels.

This session was chaired by prof. Dr. Annika Borgenstam.