Deformation path effects on the internal stress development in cold worked austenitic steel deformed in tension
No Thumbnail Available
Date
2014-07-05
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
The effects of cold work level and strain paths on the flow stress of austenitic stainless steels, including
Bauschinger effect and associated internal stresses were investigated with both mechanical testing and
neutron diffraction techniques. The main objective was to assess the effects of cold rolling: to 5%, 10%,
20% and 40% reduction and uniaxial straining on the evolution of the internal strains during the
re-straining to 5% tensile strain in-situ, which is relevant for stress corrosion cracking (SCC) studies.
The results of mechanical testing showed that the yield strength of material increased when it was
reloaded in the forward direction and decreased well below the flow stress when the loading direction
was reversed, showing a strong Bauschinger effect. The magnitude of Bauschinger effect is independent
on whether tensile or compressive prestraining comes first but rather on the amount of prestrain.
The assessment of the effect of prestraining methods showed that the magnitude of yield asymmetry
was higher in the material prestrained by uniaxial deformation than those prestrained by cold rolling.
Neutron diffraction test results showed that the elastic lattice strain difference between the maximum
and minimum strain values increased consistently with the applied stress during the re-straining to 5%
tensile strain in-situ along the 3 orthogonal directions of the rolled plate. It also emerged that, following
the in-situ loading of cold rolled materials to 5% tensile strain, the largest strain difference occurred in
the material prestrained to 20% reduction. In cold rolled samples, the peak width increased with cold
work levels and during re-straining to 5% along rolling, transverse to rolling and normal directions which
simulated reversed condition. In contrast to the cold rolled samples, there was neither increase nor
decrease in the peak width of samples prestrained by uniaxial deformation on re-straining in reverse
direction. This was rationalised in terms of the development of intragranular and intergranular stresses
in the two cases and implications to SCC susceptibility were discussed.
Description
Keywords
Stainless steel, Strain path, Cold work, Peak width, Bauschinger effect, Stress corrosion cracking
Citation
Ahmed, I. I., Grant, B., Sherry, A. H., & Quinta da Fonseca, J. (2014). Deformation path effects on the internal stress development in cold worked austenitic steel deformed in tension. Materials Science and Engineering: A, 614 (0), 326-337. doi: http://dx.doi.org/10.1016/j.msea.2014.07.005