Low-Temperature Micro-Fracture Toughness Testing of Grain Boundaries in Steel

Temper embrittlement in high-strength steel occurs due to the segregation of impurity elements along prior austenite (γ) grain boundaries, resulting a decrease intergranular strength. However, boundary properties have not yet been experimentally investigated. In this study, we developed micro testing method selectively process micro-cantilever specimens based on specific γ-grain measure fracture toughness. Fracture toughness tests using with side grooves and notch were carried out at 183 K brittle behavior was successfully obtained. The surface showed almost flat crack propagation boundary. derived value, KQ, is lower than that from previous values. By employing for evaluation fractures steel, believe can evaluate more intrinsic compared conventional methods.