Anisotropic strain in nitrided austenitic stainless steel
Abstract
Nitrogen treatment of austenitic stainless steels at temperatures around 300-400 °C leads to the formation of a hard and corrosion resistant phase called expanded austenite. The most puzzling feature of this phase is an anisotropic lattice expansion where the expansion along the (100) is about 20% larger than for the (111) direction. In this report an investigation of the lattice expansion of austenitic stainless steel after nitrogen plasma immersion ion implantation by x-ray diffraction is presented. Pole figure measurements as well as θ/2θ scans at different polar angles were performed. Comparing the data with three different structural models, fcc, tetragonal, and triclinic, it can be concluded that none of them yields good agreement with the data, so that the crystallographic characterization is still open. However, a model for the atomic origin of the observed lattice expansion based on the anisotropic Young's modulus, which is found for every fcc metal, is presented, showing good agreement with the measured data as well as data taken from the literature.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- September 2000
- DOI:
- 10.1063/1.1289520
- Bibcode:
- 2000JAP....88.3323M
- Keywords:
-
- 81.65.Lp;
- 81.05.Bx;
- 61.72.Ww;
- 81.65.Kn;
- 52.75.Rx;
- 62.20.Dc;
- 81.40.Jj;
- Surface hardening: nitridation carburization carbonitridation;
- Metals semimetals and alloys;
- Doping and impurity implantation in other materials;
- Corrosion protection;
- Elasticity elastic constants;
- Elasticity and anelasticity stress-strain relations