TWI Technical Literature Review 22959
By R Fairclough
A significant problem associated with components produced using the selective laser melting (SLM) process is the development of high internal residual stresses which are a result of the repeated heating and cooling of successive layers of powder during component build. This produces high temperature gradients and complex thermal effects within the build, which promote the development of significant residual stresses. If residual stresses are not recognised and allowed for in the design process for SLM manufactured parts, they can be a major factor in the subsequent failure of a component in service, particularly one subjected to alternating loadings or corrosive environments.
Residual stresses can also cause deformation in SLM manufactured parts which is problematic when tight dimensional tolerances are required. Often, some form of post processing (HIP or heat treatment) is required which can substantially increase manufacturing costs.