Evolution of microstructures and inclusions of 82B wire rod during drawing process
An experiment was carried out that an 82B wire rod of 12.5 mm in diameter was drawn nine passes. The evolution of the microstructures and inclusions of the 82B wire rod were observed by SEM after drawing at different strain, and the relation between pearlitic lamellar spacing and the drawing strain was investigated. The results indicate that the pearlitic lamellar spacing decreases as the drawing strain increases. And the drawn pearlitic layer distorted strongly and lamellar cementite deform along with the bending of lamellar ferrite, so they show good capability of plastic deformation. Moreover, the martensite formed owing to centre segregation is broken to pieces because of its weak plastic deformation capability in the drawing process and finally breaks away the matrix. In contrast to this, although a brittle inclusion of 10 μm in diameter has also been broken to pieces in the drawing process, the crack around the inclusion is not formed.