A forming limit framework accounting for various failure mechanisms: Localization, ductile and cleavage fracture

International Journal of Plasticity, vol. 175, pp. 103921

Abstract

The forming limits and failure properties of three distinct advanced high-strength steels (AHSS) have been investigated under various stress states in tensile tests with optimized specimen geometries. In addition to the commonly observed failure patterns governed by localized necking and ductile fracture for two of the AHSS, after substantial plastic deformation at room temperature, cleavage fracture occurs for a large range of stress states in a laboratory quenching and partitioning steel with superior tensile properties. The competition between failure patterns, encompassing ductile and cleavage fractures with and without necking, is governed by the mechanical properties of materials and the stress states, as a transition of failure mechanisms occurs with increasing triaxiality. The forming limit framework is, therefore, further extended to seamlessly integrate cleavage fracture in this study, where the competition between various failure mechanisms is demonstrated using three AHSS in the space of critical strain and principal stress. These findings shed light on the importance of considering cleavage fracture strength as a parameter besides the strength-ductility synergy in advanced high-strength metallic materials, and the proposed framework also gives a more comprehensive guide in designing and conducting the sheet metal forming processes.

Authors 6

1. Fuhui Shen corresponding Aachen Institute of Metal Forming

   RWTH Aachen University · Aalto University

   Affiliation as printed

   Advanced Manufacturing and Materials, Department of Mechanical Engineering, Aalto University, Puumiehenkuja 3, 02150 Espoo, Finland

   Institute of Metal Forming, RWTH Aachen University, Intzestraße 10, 52072 Aachen, Germany

2. Yannik Sparrer Aachen Institute of Metal Forming

   RWTH Aachen University

   Affiliation as printed

   Institute of Metal Forming, RWTH Aachen University, Intzestraße 10, 52072 Aachen, Germany

3. Jing Rao

   Max-Planck-Institut für Nachhaltige Materialien

   Affiliation as printed

   Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf, Germany

4. Markus Könemann Aachen Institute of Metal Forming

   RWTH Aachen University

   Affiliation as printed

   Institute of Metal Forming, RWTH Aachen University, Intzestraße 10, 52072 Aachen, Germany

5. Sebastian Münstermann Aachen Institute of Metal Forming

   RWTH Aachen University

   Affiliation as printed

   Institute of Metal Forming, RWTH Aachen University, Intzestraße 10, 52072 Aachen, Germany

6. Junhe Lian corresponding

   Aalto University

   Affiliation as printed

   Advanced Manufacturing and Materials, Department of Mechanical Engineering, Aalto University, Puumiehenkuja 3, 02150 Espoo, Finland