Question
During metallography, Nital is the most commonly used for etching _____________.
The correct answer is
Mild Steel
Nital Etchant Application
Nital is a widely used etchant in metallography, consisting of nitric acid dissolved in ethanol. Its primary application is for revealing the microstructure of ferrous materials, particularly steels.
Why Nital for Mild Steel?
Mild steel, being a low-carbon steel, has a characteristic microstructure (ferrite and pearlite) that is effectively revealed by Nital etching. The etchant selectively attacks different phases and grain boundaries, making the microstructure visible under a microscope.
Material Compatibility
- Mild Steel: Nital is the standard and most common etchant.
- Bronze, Brass, Aluminium: These are non-ferrous metals. Nital is generally unsuitable for etching them; different etchants (like Ferric Chloride solutions or Hydrofluoric acid-based etchants) are typically required for these materials.
Therefore, Nital is most commonly used for etching mild steel among the given options.
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Important Questions from Microstructure Ferrite Pearlite Cementite Fraction
- In optical microscopy, which one of the following combinations of wavelength ($\lambda$) and numerical aperture (NA) provides the best spatial resolution?
- A 0.2 wt.% plain carbon steel sheet is heated and equilibrated in the inter-critical region followed by instant water quenching. The microstructure of the quenched steel sheet consists of
- Which one of the following crystal structure changes occurs during the transformation of mild steel from austenite to martensite?
Magnesium treatment is carried out to produce ______________ cast iron.
- With increase in carbon content (up to 2 mass%) in Fe-C alloy, which one of the following statements is correct with respect to the lattice parameters ($c$ and $a$) of BCT martensite?
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