IABG, an insightful study about the influence of non-metallic inclusions in steel

IABG mbH (Industrieanlagen-Betriebsgesellschaft GmbH) designs and builds test benches for a variety of fields, such as springs, steering and suspension systems, mechanical actuators, electric drives, sensors, and sway bars. The corporate offer includes the engineering, manufacturing, installing, and servicing of test benches.

Today’s article is about a recent study carried out by the Ottobrunn-based company, titled “Influence of non-metallic inclusions on acceptable hcf design properties”.
More specifically, the paper discusses the results of fatigue investigations under rotating bending load for the determination of the critical inclusion sizes in different high-strength steels. The fatigue cracks that arose started from non-metallic inclusions, whose size, form, and position were determined and statistically evaluated afterwards.
The most common quality assurance method in steel production is an additional determination of the degree of cleanness derived from a microscopic evaluation of cross-sections. This very method led to a serious underestimate of the inclusion sizes and thus proved to be insufficient for the determination of relevant fatigue characteristic values.
The authors then presented a fracture-mechanics based system to derive allowable stresses depending on the size of the inclusions. This particular procedure makes the most out of the material’s fatigue resistance and optimizes the quality assurance process, minimizing failure risks during service life. Indeed, the team derived a safety factor regarding statistical size effects and the scatter of internal defects.

The complete paper in English is available for consultation here >>>