Importance of color etching to interpretation of microstructure

As a young metallurgist in the US steel industry about 50 years ago, I learned that correct identification of phases, detection of segregation, the determination of ferrite grain size, and the measurement of interlamellar spacing of pearlite were very difficult using black and white etchants such as Nital. I began to use color etchants and found that they worked much better for these studies. I will show a number of examples that demonstrate how much more detail can be seen using color etching. These examples are both interesting and beautiful!