Digital holographic microscopy as a new technique for quantitative measurement of microstructural corrosion in austenitic stainless steel

• Published in: Materials & design 2017-07, Vol.125, p.109-115
• Main Authors: Asgari, P., Pourvais, Y., Abdollahi, P., Moradi, A.R., Khamedi, R., Darudi, A.
• Format: Article
• Language: English
• Subjects: Austenitic stainless steel; Intergranular corrosion; Reflective digital holographic microscopy
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2017.03.085

The aim of this paper is to introduce reflective digital holographic microscopy (rDHM) as a new method for quantitative evaluation of corrosion. Despite the commonly-used evaluation methods, rDHM does not require scanning, while it measures the microstructural height profile of the corroded sample surface within a macroscale area. Based on the height profile across the corroded grain boundaries, a quantitative criterion is suggested to distinguish between intergranular and transgranular corrosion. The experimental results show the capability of rDHM to analyse the microstructural corrosion in AISI 304 stainless steel. The presented method can also be applied as a surface characterization method for analysis of a variety of metallurgic effects such as crystal elasticity and crystal orientation. [Display omitted] •Digital holography is introduced to quantify the intergranular corrosion (IGC).•The method provides a high-resolution 3D profile in an adjustable field of view.•A new criterion to distinguish IGC from transgranular corrosion is suggested.•AISI 304 samples are examined after being annealed in 600, 700 and 800°C.•The major corrosion type of AISI 304 samples is interchanged below and above 700°C.