Imperial College London
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DrPaulHooper

Faculty of Engineering, Department of Mechanical Engineering

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 7128paul.hooper Website CV

 
 
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Location

 

456ACity and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Williams:2020:10.1016/j.jmapro.2020.07.023,
author = {Williams, RJ and Vecchiato, F and Kelleher, J and Wenman, MR and Hooper, PA and Davies, CM},
doi = {10.1016/j.jmapro.2020.07.023},
journal = {Journal of Manufacturing Processes},
pages = {641--653},
title = {Effects of heat treatment on residual stresses in the laser powder bed fusion of 316L stainless steel: Finite element predictions and neutron diffraction measurements},
url = {http://dx.doi.org/10.1016/j.jmapro.2020.07.023},
volume = {57},
year = {2020}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Heat treatments are used in laser powder bed fusion (LPBF) to reduce residual stress and improve service life. In order to qualify components for service, the degree of stress relaxation under heat treatment must be known. In this work, the effect of heat treatment on residual stress (RS) in LPBF 316L stainless steel was studied. Finite element (FE) models were developed to predict the RS distribution in specimens in the as-built state and subjected to heat treatment. The models simulated the thermo-mechanical LPBF build process, sample removal from the build plate and creep stress relaxation effects from a 2h heat treatment at 700 C. The predictions were validated by neutron diffraction measurements in as-built and heat treated samples, in both build orientations. Large tensile RS of around 450MPa were predicted at the vertical sample's outer gauge surfaces, balanced by high compressive stresses of similar magnitude at the centre. The residual stresses in the horizontal sample were significantly lower, by around 40%. The influence of sample removal from the base plate on the RS distribution was found to be strongly dependent on the sample orientation and geometry. The heat treatment preserved the unique microstructure of the LPBF process and reduced the peak RS by around 10% in the vertical sample and 40% in the horizontal sample. The FE model predictions were found in good agreement with the experimental measurements, thus providing an effective tool for RS predictions in LPBF components and proving the effectiveness of the heat treatment on RS relaxation.
AU  - Williams,RJ
AU  - Vecchiato,F
AU  - Kelleher,J
AU  - Wenman,MR
AU  - Hooper,PA
AU  - Davies,CM
DO  - 10.1016/j.jmapro.2020.07.023
EP  - 653
PY  - 2020///
SN  - 1526-6125
SP  - 641
TI  - Effects of heat treatment on residual stresses in the laser powder bed fusion of 316L stainless steel: Finite element predictions and neutron diffraction measurements
T2  - Journal of Manufacturing Processes
UR  - http://dx.doi.org/10.1016/j.jmapro.2020.07.023
UR  - https://www.sciencedirect.com/science/article/pii/S1526612520304485?via%3Dihub
UR  - http://hdl.handle.net/10044/1/81054
VL  - 57
ER  -
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