Abstract
Eurofer97 steel is a primary structural material for applications in fusion reactors.Laser welding is a promising technique to join Eurofer97 plasma-facing components and overcome remote handling and maintenance challenges.The interaction of the induced residual stress and the heterogeneous microstruc-ture degrades the mechanical performance of such fusion components.The present study investigates the distribution of residual stress in as-welded and post-heat treated Eurofer97 joints.The mechanis-tic connections between microstructure,material properties,and residual stress are also studied.Neu-tron diffraction is used to study the through-thickness residual stress distribution in three directions,and neutron Bragg edge imaging(NBEI)is applied to study the residual strain in high spatial resolution.The microstructures and micro-hardness are characterised by electron backscatter diffraction and nanoin-dentation,respectively.The M-shaped residual stress distribution through the thickness of the as-welded weldment is observed by neutron diffraction line scans over a region of 1.41×10 mm2.These profiles are cross-validated over a larger area(-56×40 mm2)with the higher spatial resolution by NBEI.The micro-hardness value in the fusion zone of the as-welded sample almost doubles from 2.75±0.09 GPa to 5.06±0.29 GPa due to a combination of residual stress and cooling-induced martensite.Conventional post weld heat treatment(PWHT)is shown to release～90％of the residual stress but not fully restore the microstructure.By comparing its hardness with that of stress-free samples,it is found that the mi-crostructure is the primary contribution to the hardening.This study provides insight into the prediction of structural integrity for critical structural components of fusion reactors.
基金项目
Euratom Research and Training Programme 2014-2018 and 2019-2020(633053)
维普
万方数据