Abkühlung eines austenitisierten Chromstahls mit 0,2%C führt zur Ausscheidung voreutektoiden Ferrits, der sich in grobkörniger Austenitstruktur bzw. bei beschleunigter Abkühlung von zu hohen Temperaturen in Form von Nadeln und Platten bildet.

The film shows the separation of pro-eutectoid ferrite from the austenite in Widmanstätten arrangement in the form of the development of a needle profile on a polished surface in the hot stage microscope on a chrome steel with 0.20%C. The boundaries of the austenite grains are also visible. The film shots show the cooling in the sample after an austenitisation at 1200 °C, beginning at about 750 °C and endig at 570 °C in a time of about 50s. The first ferrite needles may be recognized at about 720 °C. The needles are to be seen growing, in general starting from the austenite grain boundary, in certain preferred directions often parallel to each other. The needles grow both lengthways and sideways as intersection tracks of plates. The end of the ferrite formation is reached in this case at about 600 °C.