Determination of the Plastic Zone Size by Using Nanotest for Aluminum Alloy 2024T351

The studies on crack-tip plastic zone are one of fundamental importance in describing the process of failure and in evaluation of the material life, it directly relate to the toughness of the material. The objective of this work is to study the crack-tip plastic zone size. This work utilizes the ultra-low-load at nano scale to study the cyclic and monotonic plastic zone size at the fatigue crack tip based on the relationship between the hardness, elastic work, plastic work, plasticity index and the distance from the crack tip. The nanotest is conducted on the compact tension specimen of aluminium alloy 2024T351 with stress intensity factor amplitude of 16 MPa.m(1/2) at the fatigue crack tip. We found that the relationship between hardness, elastic work, plastic work, plasticity index and distance from the fatigue crack tip are very sensitive in the plastic zone; therefore, the cyclic and monotonic plastic zone size are determined due to these relationships.