Investigation of residual stress in laser formed mild steel plates using neutron diffraction

Stefan Knupfer, Anna M. Paradowska, Oliver Kirstein, Andrew Moore

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

Forming of metal plates with a high-power laser beam is a flexible materials forming technique. Bending results from the establishment of a steep temperature gradient through the material thickness which leads to non-uniform thermal expansion/contraction and subsequently residual stresses. It is important to characterize these residual stresses as a function of process parameters such as line energy (LE) to optimize treatment conditions and to gain an insight into the mechanism of the formation of the final geometries. Non-destructive neutron diffraction measurements were carried out on ENGIN-X at ISIS and KOWARI at ANSTO to map the residual stress distribution around the heat affected zone (HAZ) of laser deformed mild steel plates for single and multiple passes as a function of line energy (LE), the primary laser forming process parameter. It was found that in the centre of the HAZ, longitudinal residual stresses are tensile and dominant, transverse stresses are predominantly tensile and normal stresses are compressive and close to zero. The residual strain in longitudinal direction increased with LE and number of passes until yielding. Even higher heat input decreased the magnitude of the cusp, but not its total height. The comparison of a stress-free reference sample, measured at both facilities, showed a small discrepancy in the lattice spacing corresponding to ~ 85 µstrain which is insignificant with respect to the experimental values measured. © (2010) Trans Tech Publications.

Original languageEnglish
Title of host publicationMechanical Stress Evaluation by Neutrons and Synchrotron Radiation
Pages123-128
Number of pages6
Volume652
DOIs
Publication statusPublished - 2010
Event5th International Conference on Mechanical Stress Evaluation by Neutrons and Synchrotron Radiation, MECA SENS V/3rd International Symposium of Quantum Beam Science Directorate of Japan Atomic Energy Agency - Mito, Japan
Duration: 10 Nov 200912 Nov 2009

Publication series

NameMaterials Science Forum
Volume652
ISSN (Print)0255-5476

Conference

Conference5th International Conference on Mechanical Stress Evaluation by Neutrons and Synchrotron Radiation, MECA SENS V/3rd International Symposium of Quantum Beam Science Directorate of Japan Atomic Energy Agency
Abbreviated titleQuBS2009
CountryJapan
CityMito
Period10/11/0912/11/09

Keywords

  • Laser forming
  • Neutron diffraction
  • Residual stress

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    Knupfer, S., Paradowska, A. M., Kirstein, O., & Moore, A. (2010). Investigation of residual stress in laser formed mild steel plates using neutron diffraction. In Mechanical Stress Evaluation by Neutrons and Synchrotron Radiation (Vol. 652, pp. 123-128). (Materials Science Forum; Vol. 652). https://doi.org/10.4028/www.scientific.net/MSF.652.123