What is a 'mesostructure' in martensitic metal

[Barry]

Hi, I am researching maraging steel material used in additive manufacturing and there are references in the literature to a mesostructure. Can anyone clarify?

 

[Astronuc]

Hi, I am researching maraging steel material used in additive manufacturing and there are references in the literature to a mesostructure. Can anyone clarify?

What is the context of the term mesostructure with respect to martensitic steel. Normally, meso refers to a domain larger than micro. In the context of materials, microstructure usually refers to grains and their structures, including second phase particles. Mesostructure would likely refer to regions larger than grains, especially where two or more types of grains, e.g., α+β, or α+γ, and so on.

Here is an article is discussing mesostructure in high strength steels, or duplex steels, such as ferritic-martensitic
https://www.researchgate.net/profile/Yoshihiko_Arao/publication/275540463_Influence_of_Mesostructure_for_Deformation_Characteristics_and_Formability_in_Dual_Phase_Steels/links/555bc3a308aec5ac22324471/Influence-of-Mesostructure-for-Deformation-Characteristics-and-Formability-in-Dual-Phase-Steels.pdf

In recent years, the attempt to control mesostructure is actively conducted to give various macroscopic properties for example mechanical property and formability. So it may be more important to predict macroscopic property analytically not from material test results but from mesostrucure. Actually the mechanical and deformation properties, dual phase metal should be subjected to influence by the combination of the each phase property and multiphase structure-induced effect. The macroscopic Dual Phase steels which is one of HSS and composed of ferrite and martensite depend on mesostructural difference such as mechanical properties and volume fraction and morphology of each phase (Sun et al., 2009).

See the section entitled, "Modelling of mesostructure"

See also - Mesostructure modelling using texture synthesis
L. Mac Manus, M. Iwasaki, K. Kamanori, S. Sato, N. A. Dodgson
http://www.cl.cam.ac.uk/research/rainbow/projects/meso/

See also - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5090574/
Microstructure and cleavage in lath martensitic steels

The complex mesostructure that develops on transforming a large-grained prior austenite grain in a prototypical lath martensitic steel is illustrated in figure 3, taken from Maki [6]. The prior austenite grains are divided into ‘packets’ that are subdivided into ‘blocks’ of martensite laths.