On surface carbides in low-temperature carburized austenitic stainless steels
Journal article, 2020

Surface carbides are occasionally found at the surface of austenitic stainless steels subjected to low-temperature carburizing surface treatments which are intended to induce an interstitially supersaturated surface layer. The crystallographic nature and chemical composition of the carbides can have a significant influence on the surface properties, especially on the corrosion resistance of the steel. However, their phase identification and chemical characterization via conventional methods (e.g. X-ray diffraction) is difficult due to their complex structure and metastable nature. In this paper, a combined metallographic and electron microscopic approach is applied to characterize the morphology and chemical composition of surface carbides found on AISI 304L and SS2343 after the same Kolsterising® treatment. Exclusively M5C2, also known as Hägg or χ-carbide was found at the surface of 304L, preferentially oriented along (111) deformation bands. In SS2343, however, χ-carbide coexisted with M7C3 (or ω-carbides) and M23C6. The carbides had preferential orientation relationships with the matrix, suggesting a carbide evolution during carburizing. All the carbides show elemental partitioning, with Cr enrichment and Ni depletion. A microstructure development sequence regarding precipitation and growth of surface carbides is proposed in this paper.

Orientation relationships

Carbide

Low-temperature carburizing

Microscopy

Precipitation

EBSD

Author

[Person e55cce0b-2703-4f6a-868b-77f560af6b75 not found]

Uddeholms AB

[Person 05a64660-1e30-41f1-b5f0-5f4e59b73233 not found]

Chalmers, Industrial and Materials Science, Materials and manufacture

[Person bf7daf6a-fda8-4c27-b81d-683282f5f835 not found]

Chalmers, Industrial and Materials Science, Materials and manufacture

[Person 458c2887-2994-450d-a9fd-e3d9f179ebd7 not found]

Chalmers, Industrial and Materials Science, Materials and manufacture

[Person 5e2cf8ef-81f4-440e-9f2a-04b72800f377 not found]

Chalmers, Industrial and Materials Science, Materials and manufacture

Materials Characterization

1044-5803 (ISSN)

Vol. 167 110462

Subject Categories

Materials Engineering

Manufacturing, Surface and Joining Technology

Materials Chemistry

Metallurgy and Metallic Materials

Corrosion Engineering

Areas of Advance

Production

Materials Science

DOI

10.1016/j.matchar.2020.110462

More information

Latest update

11/10/2020