Dear Seyed,

I am not a steel guy but I found following book in my library. “Metallographie” Schumann, V.E.B., Leipzig 1962.

Etchant for austenite grainsize of quenched and tempered steels:

5cm3 hydrochloric acid

1 g. picric acid

100 cm3 ethyl alcohol

The best results after tempering the martensite for 15 minutes at 200-250°C.

I hope this helps,

Cor van Ettinger

Cornelis Joannes van Ettinger

thank you

Suggestion by Cornelis Joannes van Ettinger seems quite good. Additionally, you may refer the following literature:

Sinha et al, "Delineation of Prior Austenite Grain Boundaries in a Low-Alloy High-Performance Steel"

Zhang and Guo, "A general etchant for revealing prior-austenite grain boundaries in steels"

Aman Arora

thanks for your kindly response