New Cross-Section Sample Preparation Method Applied to Microstructural and Chemical Investigation of Steel Coatings using FE-SEM
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- 1472 |
- October 20, 2020 |
- Applications, Sample Preparation |
Steel strips coated with Al-43.5Zn-1.5Si (Galvalume) alloy exhibit superior corrosion resistance as compared to Zn galvanized steel strips. The continuous hot-dip coating process used to produce such coatings entails a metallurgical reaction between the steel strip and Al-Zn-Si liquid alloy that leads to formation of an intermetallic compound layer at the steel-coating interface. Formability of the coated strip depends strongly on the morphology, dimensions (thickness) and chemical nature of this intermetallic layer. Proper characterization of the intermetallic layer structure and chemistry and the nucleation sites on the steel surface is therefore of paramount importance for the development of formable Galvalume coated steel strips. This requires preparation of artifact free cross-sectional samples. Such samples can be obtained using JEOL Cross-section Polisher (CP). Unlike mechanical sample preparation techniques that introduce significant amount of strain and possible artifacts due to preferential etching of various constituents, the CP uses a broad Ar beam and a rocking stage that minimize possible preferential etching and produces strain free cross-sections. In this paper, SEM images as well as chemical (EDS) data characterizing the interface layer between the steel strip and the Galvalume coating prepared using Cross-sectional Polisher are presented.