Fraunhofer IWM Builds a Fatigue Prediction Tool for Metal 3D Prints

The Fatigue Problem in Metal AM

Metal 3D printing can make parts that would be impossible to machine, but that freedom comes with a catch. Surface roughness, tiny pores, and tensile residual stresses can all act as crack starters. In safety-critical industries like aerospace, automotive, and energy, those flaws have kept many additively manufactured metal parts on the bench.

Fraunhofer IWM in Freiburg, Germany, has now published a calculation chain designed to fix that bottleneck. The tool predicts how mechanical surface treatments such as shot peening, deep rolling, and burnishing change the fatigue strength of a metal AM component. Instead of running dozens of physical tests, engineers can compare post-processing strategies on a screen first.

How the Workflow Works

The method splits into three stages. First, the component is assessed and the right post-treatment is chosen based on geometry and stress concentration. Second, a process simulation predicts surface layer properties: residual stresses, roughness, and hardening. Third, the team runs an FKM-based fatigue life assessment, adapted specifically for additively manufactured AlSi10Mg, 316L stainless steel, and Ti6Al4V.

The project was funded by Germanys Federal Ministry for Economic Affairs and Energy. Validation tests showed fatigue strength improvements of up to 40%, along with better predicted service life. Those numbers matter because fatigue failures almost always start at the surface, so a well-chosen surface treatment can compensate for variability in the print itself.

From Specimens to Components

The researchers tested the chain on both small specimens and actual components. The goal is to move the decision-making earlier in product development. Engineers can now pick a post-processing strategy before committing to a long test cycle.

Fraunhofer calls this the first computer-aided design methodology built specifically for mechanical surface post-processing of additively manufactured metal parts. If it scales, it could lower one of the biggest barriers keeping metal AM out of load-bearing applications.