Continuous damage mechanic descriptions or micromechanical constitutive models are often used for ductile failure prediction. Nevertheless, these approaches cannot describe post fracture behaviour and one can resort to continuous/discontinuous methodologies to follow its propagation. Practical solutions often adopted include element erosion or approaches based on remeshing tecniques. More sophisticated methods based on the X-FEM concept, in particular associated with non-local formulations, have been attempted. Nevertheless, some important aspects are often neglected, in particular when energetic requirements to promote the necessary transition of energy release from damage to fracture should be taken into account. Phase-field methods are somewhat novel approaches to blend the advantages of continuous and discontinuous models by using a similar description to non-local methods in order to “continuously” follow crack evolution and branching; ACKNOWLEDGEMENT: Authors gratefully acknowledge the funding of Project NORTE-01-0145-FEDER-000022 - SciTech - Science and Technology for Competitive and Sustainable Industries, co-financed by Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER)
Austenitization is well studied process in steels with pearlitic and spheroidised structures. Bainite as original microstructure for austenite formation is not so frequent. This article describes austenitization of bainitic structure of 51CrV4 spring steel. The experimental steel was austenitized in dilatometer capable of rapid temperature changes. Isothermal resp. anisothermal austenitization was studied at different temperatures resp. heating rates with respect to its kinetics and microstructural features. Special attention was paid to the morphology of growing austenite grains and carbide morphology during their dissolution in austenite.
Rapid partial austenitization can result in accelerated carbide spheroidisation. This phenomenon is known for pearlitic structures. This article shows that bainite can be spheroidised in similar way as pearlite. Accelerated carbide spheroidisation can be applied as replacement of conventional time-consuming spheroidisation annealing.
Prof. Zrník Anniversary Session