Numerical modelling approach for considering effects of surface integrity on micro-crack formation

J Nafar Dastgerdi,F Sheibanian,H Remes,P Lehto,H Hosseini Toudeshky

doi:10.1016/j.jcsr.2020.106387

J Nafar Dastgerdi, F Sheibanian + Show 3 more

Open Access

https://doi.org/10.1016/j.jcsr.2020.106387

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Abstract

This work studies the simultaneous effects of surface roughness and residual stress on the micro-crack formation under peak load conditions. The manufacturing process of e.g. steel components influences the surface topography and the material microstructure. These changes affect the surface integrity, which in turn define the component's mechanical properties such as fatigue strength. This paper introduces an efficient finite-element based approach to analyze the influence of surface roughness, residual stress, and microstructural composition on micro-crack formation mechanism during monotonic peak load. The proposed approach combines surface roughness profiles, a ductile fracture criterion and a layer-wise residual stress definition for an approach that is suitable for surface integrity analysis. An inverse numerical-experimental approach is presented for the calibration of the ductile fracture criterion under different stress states. The developed approach is applied to a sandblasted S690 high strength steel, in which the surface integrity has been altered by the manufacturing process. The possibility of crack initiation in the vicinity of critical micro notches is investigated, and the influence of surface roughness and residual stresses is studied. The proposed modelling principles and calibration approach can be employed for other materials and surface profiles.

Highlights

The manufacturing process of metal components influences surface integrity which defines the properties of final components, affecting for instance corrosion and fatigue resistance; see e.g. [1,2,3,4]
Surface integrity is usually described by several parameters: (i) a geometrical parameter i.e. surface topography, (ii) a mechanical parameter i.e. residual stress, and (iii) a metallurgical parameter i.e. microstructural composition
Most of the previous works [12,13,14,15] studied the influence of individual parameters, mainly surface roughness on the fatigue performance of different engineering materials; the formation of micro-cracks is often neglected in fatigue strength assessment

Summary

Introduction

The manufacturing process of metal components influences surface integrity which defines the properties of final components, affecting for instance corrosion and fatigue resistance; see e.g. [1,2,3,4]. Surface integrity is usually described by several parameters: (i) a geometrical parameter i.e. surface topography, (ii) a mechanical parameter i.e. residual stress, and (iii) a metallurgical parameter i.e. microstructural composition. These parameters vary depending on the used manufacturing methods and environmental conditions [5,6,7]. Most of the previous works [12,13,14,15] studied the influence of individual parameters, mainly surface roughness on the fatigue performance of different engineering materials; the formation of micro-cracks is often neglected in fatigue strength assessment. It is crucial to investigate the combined effect of surface integrity parameters on the properties and micro-cracking of engineering components under peak loads

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