Characterisation of stainless steel surfaces – modified in air at 350°C

Abstract

This work aimed to modify stainless steel surface by oxidation for metal-plastic hybrid applications. Oxidation behaviour of the stainless steels AISI 304 and 316L was studied by TEM and AFM. Air exposures for steels were carried out in air at 350°C for 5–300 min. The oxide layer structures were characterised by planar and cross-sectional TEM samples. Behaviours of the both steels were very similar. Oxidation started already during first 5 min and a protective oxide layer formed fast and further oxidation was slower. Oxide structures were mainly of the type M₂O₃. Surface topography of the oxide layer was studied by AFM. At first, single oxide islands formed on the base oxide layer. After 100 and 300 min exposures, the islands have combined to the thin, uniform and dense oxide layer. Owing to this, an optimal stainless steel insert surface for metal-plastic hybrid parts would be after those treatments.