ADIABATIC SHEAR BAND FORMATION AND ITS MICROSTRUCTURES PRODUCED BY HIGH SPEED PENETRATION IN 30MnCrNiMoB LOW ALLOY STEEL

The formation mechanism of adiabatic shear band(ASB) produced by high speed penetration in 30MnCrNiMoB low alloy steel was studied.During the deformation process.there are not only a thermal softening and the usual strain hardening,another strain softening due to the dynamic emission of dislocations from F-R(Frank-Read) sources should be considered.Experimental observations show that there is periodic structure along ASB,i.e.periodic crack branching along ASB and periodic arrangement of tear ledges on the crack surface along ASB trace.The physical mechanism of the periodic structure is discussed.