Multiple Influences of Molybdenum on the Precipitation Process in a Martensitic PH Stainless Steel
Journal article, 2019

Molybdenum has been found to influence the complex precipitation process in a martensitic precipitation hardening stainless steel during aging at 475 degrees C in several different ways. Three steels with different Mo content (0, 1.2 and 2.3 at.%) were investigated. Studies of the microstructure were performed with atom probe tomography and energy filtered transmission electron microscopy. It is shown that, at the initial stage of aging, a faster nucleation of Cu-rich clusters takes place with increasing Mo content. The Cu-clusters act as precipitation sites for other solute elements and promote the nucleation of Ni-rich phases. During further aging, a higher Mo content in the material instead slows down the growth and coarsening of the Ni-rich phases, because Mo segregates to the interface between precipitate and matrix. Additionally, Mo promotes decomposition of the matrix into alpha and alpha' regions. After longer aging times (>40 h) quasicrystalline Mo-rich R' phase forms (to a greater extent in the material having the highest Mo content). The observations serve to understand the hardness evolution during aging.

energy filtered transmission electron microscopy

atom probe tomography

aging

stainless steels

precipitation

Author

Mattias Thuvander

Chalmers, Physics, Microstructure Physics

Marcus Andersson

SKF Sverige AB

Krystyna Marta Stiller

Chalmers, Physics, Microstructure Physics

Metals

2075-4701 (eISSN)

Vol. 9 10 1118

Subject Categories

Materials Chemistry

Other Materials Engineering

Metallurgy and Metallic Materials

DOI

10.3390/met9101118

More information

Latest update

8/28/2020