The future DEMO fusion energy reactor will need to operate in a near continuous mode putting great demands on materials and components in terms of heat load and irradiation. Most parts of DEMO will be made of multi-material assemblies which are difficult to fabricate and cause high, through thickness residual stress that need to be accurately calculated so that they can be included in the overall calculation of operation stresses used for design assessment. We propose to measure two test pieces of composite W-steel + copper-based brazing, with 1.5 mm and 1.0 mm ‘pipe’ thickness. The total thickness of W is of only a few mm, in order not to affect the neutron beam. The specimens are readily available. Measurements will be taken by scanning at least 7 radial positions and two locations on each part, in order to measure all the relevant components of residual stress.