The Effect of Mean Stress and Thermo-Mechanical Induced Stress on Micro-Crack Initiation: An Analysis Based on Experiments and DD Simulation Results

Christian F. Robertson; Christophe Déprés; Marc Fivel

doi:10.4028/www.scientific.net/MSF.567-568.89

Paper Titles

Tensile Strength of Perfect Cubic Crystals under Superimposed Transverse Plain Stress
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Ideal Tensile Strength of Ni₃Al and Fe₃Al with D0₃ Structure
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Monte Carlo Simulation of Normal Grain Growth in Three Dimensions
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The Effect of Grain Size on the Deformation Behaviour of Selected Mg Alloys
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The Effect of Mean Stress and Thermo-Mechanical Induced Stress on Micro-Crack Initiation: An Analysis Based on Experiments and DD Simulation Results
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Significance of Microdefects Induced by ECAP in Aluminium, Al-0.2%Sc Alloy and Copper
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Simulation of the Cyclic Response of 316L Single Crystals and Polycrystal Using Three Dimensional Elastic-Plastic Crystalline Finite Element Computations
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Microstructure-Aided Analysis of Fatigue Thresholds in Duplex Stainless Steel
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Analysis of a Transversal Crack in a Steel Slab
p.105

HomeMaterials Science ForumMaterials Science Forum Vols. 567-568The Effect of Mean Stress and Thermo-Mechanical...

The Effect of Mean Stress and Thermo-Mechanical Induced Stress on Micro-Crack Initiation: An Analysis Based on Experiments and DD Simulation Results

Abstract:

The combined effect of cyclic thermal shocks and static tensile loading is investigated, in a 304L stainless steel. During these experiments, the stress state in the cylindrical specimen walls is nearly equi-biaxial (σZZ ≈ σθθ). In dislocation dynamics (DD) simulations carried out with σZZ = σθθ, the predominant slip directions b are nearly aligned with the free surface normal vector n, regardless of their associated activation ratio (A.R.). This effect is related to the "surface connected volume" (SCV) of the predominant slip systems. Hence, surface grains with n = <110> possess "large SCV slip systems" and therefore, constitute preferential sites for micro-crack initiation in thermal fatigue. During the tests, a marked effect of the superimposed static tensile loading (or mean stress) is also noted. This effect is explained with the help of DD simulations performed with a positive mean stress: slip irreversibility in the individual persistent slip bands systematically augments with increasing mean stress.