This direction covers measurement methods, result reliability and process control of residual stress in engineering components, including welded joints, thick sections, surface-hardened layers and additively manufactured parts.

On measurement, results from neutron diffraction, high-energy synchrotron diffraction, laboratory X-ray sin2psi and cosalpha methods and the contour method are compared on the same component, and the differences in spatial resolution, penetration depth and range of applicability are stated. Two common problems are addressed: determination of the stress-free parameter d0, handled by joint inversion of stress and d0 to reduce reliance on reference coupons, and gauge-volume and pseudo-strain corrections in near-surface gradient measurement.

On process control, the effect of shot peening, laser shock peening and their combination on the residual stress depth profile is studied, linking process parameters and gradient descriptors (surface stress, compressive peak and crossover depth) to fatigue performance, with the aim of delivering process windows and acceptance criteria. On method selection, a suitability assessment tool is developed to judge, before beamtime or a test campaign is committed, which method suits a given component and where each method reaches its limit.

The three parts are connected: measurement establishes the actual stress state, process control changes it, and suitability assessment decides which route gives a reliable result.