Analysis on the Microstructural Evolution and Adiabatic Shear Performance in Electro Iron-DT4

Microstructural evolution of adiabatic shear bands(ASB) in DT4 has been investigated.Tests were performed using a specially designed stepped specimen and Hopkinson bar.The results showed that the fracture surface of the shear band was characterized by(1) regions of elongated dimples within which no second phase particles were observed,and(2) regions with a relatively flat and smeared appearance.The granula in the region between the center of adiabatic shear band and matrix exhibited some preferred orientation.Electron diffraction patterns appear as some discontinuous ellipses and rings within the regions of elongated dimples in the forged electro iron and rolled electro iron respectively.The dislocation is very low in the ASB.At the same time,high dislocations were found in microstructure of adjacent matrices.Microgranules in center of shear band in DT4 was symmetrical with an average diameter less than 0.5?μm.