| This is the first paper of a series of papers on adiabatic shear band formed in an HY-100 steel under dynamic torsional loading. In the present study, the formation process of adiabatic shear band in an HY-100 steel was observed by means of a high speed photography in conjunction with the stress-strain behavior. A torsional Kolsky bar was employed to impose dynamic torsional loading, a strain rate of about 1500/s, in a thin walled tubular specimen. The results show three consecutive stages of plastic deformation process in the HY-100 steel. The first stage starts immediately after initial yield and consists of homogeneous deformation. This is followed by the second stage which the strain becomes to localize into a rather broad band. As deformation continued, at the final stage, the region of high local strain narrows to form a shear band. The adiabatic shear band leads to final failure resulting from the loss of load carrying capacity of the material. Microscopic study shows that fracture process involves formation and coalescence of voids and microcracks initiated at MnS and carbide particles. A preliminary TEM study reveals development of fine dislocation cell structure within the shear band. |
|
