Multi-axial fatigue initiation at inclusions and subsequent crack growth in a bainitic high strength roller bearing steel at uniaxial experiments

• The behaviour of inclusion initiated fatigue was studied for a high strength bearing steel with a bainite micro-structure. The analysis included experiments and numerical simulations. It was realized that the stress-state was multi-axial in the matrix material that met the inclusion also for a uniaxial far field stress. Fatigue initiation risk at the interface between the inclusion and matrix material was therefore predicted with the Findley multi-axial critical plane criterion. The fatigue parameters were determined from independent experiments on smooth specimens with tensile surface stress gradients. Crack growth from the inclusion to final rupture was modelled as a penny shaped crack with closure compensated effective material parameters. The growth simulations suggested that the majority of the fatigue life was consumed as fatigue crack initiation at the non-metallic inclusion.

Nyckelord

Bainite

Fatigue crack growth

Fatigue initiation

High strength steel

Inclusions

Bearing steels

Critical planes

Far-field stress

Fatigue crack initiation

Fatigue parameter

Growth simulation

High strength

Material parameter

Matrix materials

Multi-axial fatigue

Non-metallic inclusions

Penny-shaped crack

Roller bearing steel

Tensile surface stress

Crack closure

Experiments

Fatigue crack propagation

Fatigue of materials

Interfaces (materials)

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ref (ämneskategori)

art (ämneskategori)