Abstract:

High strength alloys are widely applied in structures such as automobile since they have many advantages such as safety promotion and weight reduction. On the other hand, fracture of metals and alloys is commonly seen in our daily life due to inappropriate design or long-time service, which has caused enormous economic loss or even human death every year. To make this worse, materials with higher strength tend to be more susceptible to fracture, which is the so-called strength-toughness trade-off. This trade-off disables the application of high strength materials in structures where overloading, fatigue and damage are major concerns. Therefore, it is desirable for us to break this natural limit and design materials with both high strength and toughness, which requires us to understand the fracture mechanism of materials from atomic to macro level in order to further prevent fracture. In this seminar, different fracture features and related concepts of fracture in high strength alloys such as plane strain fracture toughness are discussed and analyzed firstly. Then the fracture toughness testing according to the ASTM standard is introduced, which can quantitatively measure the resistance of a material to crack initiation and growth. Besides, some available approaches to enhance fracture toughness from recent literatures are reviewed. Besides, my recent work and some preliminary results are presented.