SCCAM - Residual stresses and SCC in additively manufactured stainless steel by neutron diffraction

Purpose and goal

Residual stress is one of the main issues which limits the full potential of SLM manufacturing technologies for manufacturing stainless steel parts for critical applications. The aim of the work is to characterize residual stress in large SLM build stainless steel with industrially relevant size and investigate whether it is possible to combine residual stress relaxation operation with HIP treatments. The project participants include Quintus technologies as SLM and HIP treatment experts from the industry, and Swerim as method expertise and project coordinator.

Expected results and effects

The possibility of combining stress relaxation with HIP without changing the process quality and cost is confirmed and the effect of the HIP condition on stress is shown. Furthermore, the experimental data validate a previously developed numerical model aimed at simulating the stress in SLM-built steel after HIP. The work deepened the Quintus technologies knowledge on HIP treatment of SLM-built steel and the use of large-scale facilities. The results of the work might help the SLM industry to cut the manufacturing cost and lead time of high-end SLM-built steel products.

Planned approach and implementation

Large stainless steel samples were built using the SLM and HIP treated by the Quintus with conditions relevant to their product guidelines. Then, the strain in all samples including a reference sample was mapped using neutron Bragg-edge imaging setup at the IMAT and diffraction setup at the Engine-X beamline of ISIS (UK). Stress at the near-surface of the sample was also measured at the P61A beamline of DESY. For all beamlines, the stress measurement and data analysis pipelines were developed and shared in the project forum. Parts of the result were presented in a conference and a journal.