An analysis of plastic instability in pure shear in high strength AISI 4340 steel

摘要: The phenomenon of plastic instability in pure shear was studied at room temperature heat treated high-strength AISI 4340 steels, employing the torsion test. occurs after saturation strain hardening by dispersed carbide particles. onset is sensitively dependent on rate straining. effective stress (total minus resulting from dispersion hardening) may be a result Snoek relaxation or Cottrell drag, depending rate; magnitude this linearly proportional to dissolved carbon content. Experimental observations indicate that interfaces advance spirally axial direction specimen. It proposed interface stable thermodynamic sense and driving force for migration depends only ratio speed front macroscopic rate. When becomes stationary, fracture nucleated an distortion interface. Fracture translatory motion one now rigid body with respect second along characteristic (slip) surface. Pores found surface, but these are incidental intense flow characteristic, not cause instability.