Pre-material defect , cracks at the billet - 1.6582
The concept, pre-material defect, has different meanings. Depending on processing stage, it is always to understand something else by a pre-material defect. For a drawer a rolling defect is a pre-material defect at the basic material in front of the drawing. From the view of a worker in a rolling mill, defects which are already available at the billet, for example scals or cracks at the corner, are to describe as pre-material defects. These defects then are existing usually furthermore at the ready rod wire or steel bar, if they are not too small so that they could burn down in the formed scale of the material. In the following example, cracks at the billet were responsible for the defect picture at the rod wire. Distinctively for this kind of pre-material defect, is the amplified available and wedge shaped appearing decarburization, in the environment of the defect and the strong branching of the crack.
Rod wire 25,00 mm round - spheroidised