Dear Reza Hosseinabadi, the Widmanstätten structure is observed when Austenite crystals are too big or when it is quenched too fast from high temperatures. Here the γ→α Transformation from Austenite to Ferrite is abnormal. It is formed due to Segregation during fast quenching of a coarse Austenite grain structure, after the temperature went below the Ac3 (cf. iron-carbon diagram). Within the relatively large Austenite grains pre-eutectoid Ferrite is formed with acicular respectively plate like structure, which is embedded is a perlitic Matrix. Within a fine grained Austenite the Ferrite would form at the grain boundaries; in the Widmannstätten-structure the Ferrite is not formed at the grain boundaries, but within the Austenite grains as Ferrite plates on the prefered crystallographic lattice planes.