Composition: Carbon steel (0.35%C, hypoeutectoid).

Processing: Hot-rolled. Annealing (870ºC - 1h), Water quenching, Tempering (600ºC - 4d).

Etching: 10-15 s immersion in 2% nital.

This is very similar to the X26 specimen, but with a longer tempering time (from 2 h to 4 days). This increase in time results in slightly larger cementite particles. It can also be seen in the micrographs that the acicular shape of ferrite gradually disappears and is replaced by one that is equiaxial.  

Fe-Fe₃C diagram

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