Observations of decomposition of martensite during heat treatment of steels using atom probe tomography

Abstract

Abstract. The decomposition of martensite during tempering or ageing is an important phenomenon as it leads to changes in the mechanical properties. These changes could take place during both steel manufacturing or in-service. Thus, their understanding is required to predict the material performance. Recent advances in the development of local electrode atom probes has led to a significant increase in the analysed volume of material (up to 100 millions of atoms) and at the same time reduced the acquisition times. This allows improvement in data statistics when investigating fine nanoscale features, such as solute segregation, clustering and ultrafine precipitation. Selected results of atom probe studies on the decomposition of martensite from bake hardening of a pre-strained Transformation Induced Plasticity (TRIP) steel and ageing of FeNiTiMnAl maraging steel are presented.

Vanadium microalloying for ultra-high strength steel sheet treated by hot-dip metallising

“…11 was similar to examples from APT in the literature e.g. 8,13,14 Carbon is mainly segregated to lath boundaries and dislocations while other elements are homogeneously dispersed. Apparent enrichment of some other elements at the lath boundary in Fig.…”

High-resolution characterization of the martensite-austenite constituent in a carbide-free bainitic steel

“…This is consistent with findings by Lerchbacher et al[58] who also related the degree of carbon segregation in quenched martensite to the formation temperature of the laths, with higher temperatures leading to enhanced segregation. Carbon clusters have also been observed in quenched martensite of transformation-induced plasticity steels[59][60][61] and bainitic ferrite[62] by APT and are considered as nucleation sites for carbides. The 1D concentration profile inFig.…”