Deformation- and fracture behavior of advanced materials

The life-time of a component is confined by the nucleation and growth of small defects during production and in service; the material is successively damaged until the component fails or cannot fulfil a necessary function. It is clear that the durability, i.e. the resistance against the nucleation and growth of defects, plays an important role in the development of new materials.

We investigate the basic physical processes of damage nucleation and -evolution in materials as functions of their micro- or nanostructure and the loading conditions. A deep understanding, how microstructure and loading conditions influence the deformation-, fatigue- and fracture properties is prerequisite for the development of improved materials. Such investigations are currently performed on advanced high-strength steels, Fe-Si-Al-alloys, tungsten alloys, and various nanocrystalline materials that are produced by severe plastic deformation.

SEM-micrograph of a dual-phase steel with very fine microstructure containing soft ferrite and hard martensite (left). Positions with high strain (“hot spots”) are visible in the local strain analysis. These are preferred damage nucleation sites. From M. Kapp, Ph.D. thesis, Leoben 2011.

 

Important publications

I. Sabirov, O. Kolednik, Local and global measures of the fracture toughness of metal matrix composites. Materials Science and Engineering A527 (2010) 3100-3110.

M. Kapp, T. Hebesberger, O. Kolednik, A micro-level strain analysis of a high-strength dual-phase steel. International Journal of Materials Research 102 (2011) 687-691.

B. Gludovatz, S. Wurster, A. Hoffmann, R. Pippan, A study into the crack propagation resistance of pure tungsten. Engineering Fracture Mechanics 100 (2013) 76-85.

A. Hohenwarter, R. Pippan, Fracture of ECAP-deformed iron and the role of extrinsic toughening mechanisms. Acta Materialia 61 (2013) 2973-2983.

 

Damage nucleation in dual phase steel