Enhanced hardening by multiple microalloying in low carbon ferritic steels with interphase precipitation

The interphase precipitation behaviors and resultant hardening in V-microalloyed low carbon steels combined with Nb or Ti addition were investigated. After isothermal transformation at 923 K, alloy carbide is formed by simultaneous interphase precipitation of carbide-forming elements, with the enrichment of Nb or Ti rather than V at the early stage due to their larger driving force for precipitation. When compared at the same total amount of microalloying addition, both number density and size of alloy carbide, as well as resultant hardness of ferrite in the multiple-added alloys are in between those of the single added counterparts. The advantage of multiple microalloying of elements with different carbide-forming tendency is summarized to be the co-establishment of high number density and large volume fraction of alloy carbide with acceptable austenitizing temperature required for complete dissolution of the added carbide-forming elements.(c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

The interphase precipitation behaviors and hardening effects in V-microalloyed low carbon steels with Nb or Ti addition were investigated. It was found that the multiple-added alloys exhibit advantages in terms of alloy carbide density, size, and ferrite hardness.