Yes, the microstructure of the same material can show variations in grain size after being etched with two distinct etchants.

The grain size of a material is a function of various factors such as the processing history, heat treatment, and the chemical environment. When a material is etched with a particular etchant, the chemical reaction between the etchant and the material's surface can alter the surface topography and reveal the microstructure of the material.

Different etchants have different chemical compositions, and they react differently with the material's surface. As a result, different etchants can reveal different features of the material's microstructure, including the grain size.

For example, some etchants preferentially attack the grain boundaries, while others attack the grains themselves. If two different etchants are used, one that attacks the grain boundaries and another that attacks the grains themselves, the resulting microstructures may look different, with variations in the grain size.

Therefore, it is possible for the microstructure of the same material to show variations in grain size after being etched with two distinct etchants.

Thé microstrcture (in size) of thé same solide material can be changed aftre thermic or thermomechanical treatment but not under chimic eatching

The etchant does not directly affect the grain size. surface appearance can and will vary with different chemicals.

I also had difficulty etching fine grained HSLAS. It was very difficult to find the right exposure time. Pikral, by the way, showed incomprehensible results )

Dear Qanita,

As far my experience with chemical etching, the etchant can only modified the appearance of surface of the materials, and it can't directly influence the grain size. Grain size mainly depends on the heat treatment process, however there are few studies showing that the imposed plastic strain can also migrate the grain boundaries and therefore modify the grain size.

Any grain boundary migration required a huge amount of energy, and I think if the etchant that you used are capable to produce such amount of energy under some chemical reactions, only then it can happened. However, the possibility of such situations is still questionable!!

Dear Qanita,

the action of an etchant on the material is focused on high-energy locations which can be grain boundaries and/or phases, or even the simple matrix when under particular stress conditions (i.e., thermo-dependent tensile stresses). Depending on the etchant used, one or more of these features will be highlighted most. However, this does not intrinsically modify the real grain size, which remains the same.

However, etching is affected by many drawbacks, even when using the same identical composition of the etchant. Problems like the aging of the solution, misuse by the user, and surface to etch not perfectly clean or dry, are some examples. All these can make the repeatability of the etching questionable.

If you are really interested in calculating the average grain size distribution, I would advise you to use scanning electron microscopy (SEM)-based diffraction techniques, such as the Electron Backscattered Diffraction (EBSD). In this case, what you observe is the real grain boundary, unaffected by external factors which affect etching. Not to mention the high repeatability of the technique.

Hope it helps. Good luck with the work.

What are you measuring the as-rolled ferrite grain size or prior austenitic?

The microstructure of the same material can show variations in grain size after being etched with two distinct etchants. The grain size of a material is a function of various factors such as the processing history, heat treatment, and the chemical environment. If two different etchants are used, one that attacks the grain boundaries and another that attacks the grains themselves, the resulting microstructures may look different, with variations in the grain size.