HRTEM investigations on nano precipitates in Custom 475 maraging stainless steel
Journal
Materials Characterization
Journal Volume
178
Date Issued
2021
Author(s)
Abstract
In this work, nano precipitates in stainless maraging steel (Custom 475) were investigated using high-resolution transmission electron microscopy. In this steel, aging induces three transformation products, NiAl-B2 phase, R phase and austenite, which contribute various hardening effects dependent on the aging temperature. In the steel aged at 480 °C, precipitation of NiAl-B2 phase was the primary reaction and led to slow incremental hardening. No hardening effect was observed in the steel aged at 650 °C despite the presence of austenite of over 25 vol% and coarse B2 and R phases. Efficient hardening was obtained by aging at 520 °C, and the maximum hardness (601 HV) was achieved when the steel was aged for 4 h. This high strength is attributed to the formation of both B2 and R nano precipitates. Moreover, lattice images and diffractograms clarified the crystal structure of the R phase and its orientation relationship with the martensite matrix. This work provides comprehensive insights into precipitation behaviors in Custom 475 maraging steel. ? 2021 Elsevier Inc.
Type
journal article