Plastic zones formation under different types of loading conditions

Abstract

The plastic zone formation under the fracture surface in materials posessing a Body-Centered Cubic Lattice (BCC) structure (steel 20, 40, 45, St 3, 15X2MφA) and materials posessing a Fece-Centered Cubic Lattice (FCC) structure (aluminium alloy D16 and austenitic steels 40Γ18φ, 40X4Γ18φ, 03X13AΓ19, 07X13H4AΓ20) was studied by the X-Ray Diffraction method. Specimens were tested under a static, impact, high-speed impulse, cyclic (fatigue) and impact-cyclic loading conditions at the wide temperature range. It was shown that two plastic zones were formed under all above types of loading conditions if the plane stress state was attained at the crack tip. Only one micro-plastic zone is formed under the plane strain deformation state. A scheme of two plastic zones formation at the crack tip of specimens tested under a static, impact and impulse types of loading conditions is presented. Besides that, it was found that both impulse and impact-cyclic loadings resulted in not only plastic zones formation but work hardening of the material of specimens.