Deformation twinning and the transition temperature of ferritic steels

The appearance of deformation twins in the wide temperature region of three structural ferritic steels was analyzed. It was found that the deformation twinning was associated with cleavage fracture. These results were verifie d in more detail on technically pure bcc Fe. For two grain sizes the tensil e tests at two different strain rates and impact tests proved deformation t winning in the transition region of technically pure bcc Fe. In ductile spe cimens the deformation twinning was not observed. The fractographic analysi s of cleaved specimens proved the reinitiation of cleavage on the twin boun dary. Based on the experimental results, a linkage between the transition t emperature and deformation twinning in ferritic steels can be assumed.