Strain rate sensitivity and toughness behaviour of ductile iron under specific loading

Abstract

An efficient assessment of the mechanical properties of ductile iron (DI) under dynamic loading is usually missing. To address this gap, a plasticity model for DI grade EN-GJS-500-14 was suggested. Fracture mechanics (FM) and Charpy impact (CI) tests, high-speed and impact tensile tests as well as tensile tests at variable temperature and stress states were carried out on DIs with silicon contents from 2.10 to 3.64 wt-%. Toughness-related results indicate a difference in the transition temperatures of 100–140 K between CI and FM tests. The reason for this is assumed to be a pronounced strain rate sensitivity, which could be confirmed in the study. The plasticity model was able to predict toughness properties in CI tests.

Study of fractography of ferritic ductile iron at different temperatures and loading conditions

“…There are four common failure modes of metal materials, which are cleavage fracture, ductile fracture, intergranular fracture, and fatigue [4,5]. The mechanical properties and fracture mechanism of ductile iron at different conditions have mainly been investigated [6][7][8][9][10][11][12]. In the in situ experiment, Di Cocco [13] observed the surface of tensile specimen by scanning electron microscope, and found that the main damage mechanism of FDI is the nucleation and propagation of graphite nodule cracks caused by the decrease of solubility of γ phase carbon ('Onion-like' mechanism).…”