Metallographic Characterisation of Cold Worked Type 304 Austenitic Stainless Steels
No Thumbnail Available
Date
2007-09
Journal Title
Journal ISSN
Volume Title
Publisher
Materials Performance Centre, University of Manchester
Abstract
The influence of cold work on the Stress Corrosion Cracking (SCC) susceptibility of Austenitic
Stainless Steels (ASS) is an ongoing topic of research. While some workers have suggested that
low levels of cold work are deleterious to SCC, others argue that high levels may be favourable
to SCC under certain conditions.
The objective of this report is to quantify a number of key parameters associated with the
influence of cold work on SCC susceptibility. The microstructures of ASS subjected to
different deformation modes and different levels of cold work have been examined using a
range of techniques: optical metallography was carried out to determine the grain size and
elongation ratio; the X-ray diffraction technique was used to quantify the amount of strain-
induced martensite and residual stress; and lastly, deformation texture was examined using
Electron Back Scatter Diffraction (EBSD) technique. In addition, Vickers hardness was used to
quantify the material hardness in each condition of cold work.
The outcome of the characterisation showed that the Vickers hardness and the volume fraction
of strain induced martensite increases with both increasing levels of cold work and weight
percent of carbon in the material composition. The stability of delta ferrite was also affected by
the proportion of ferrite-stabilising elements (e.g. Si) in the composition. Bi-rolling (i.e. cross-
rolling) significantly increased the hardness value and the amount of strain induced martensite
compared with samples in which cold work was generated either by uniaxial rolling and pulling
(i.e. tensile cycling). Cross-rolling also led to a more uniform distribution of delta-ferrite
within the microstructure than either unidirectional rolling or pulling.
Description
Keywords
Citation
Ahmed, I. I., Scenini, F., & Sherry, A. H. (2007). Metallographic Characterisation of Cold Worked Type 304 Austenitic Stainless Steels. Manchester: Materials Performance Centre, University of Manchester.