Enhancing bearing lifespan with load-adapted hybrid components via laser-based directed energy deposition repair

In the context of sustainability, the repair of damaged components is of paramount importance. Rolling bearings facilitate the operation of rotating components with high loads and torques, which are utilised in various applications and can attain diameters of several metres. The larger the bearing, the more economically and ecologically viable the repair becomes. In the present study, the repair was achieved through the development of a process chain based on welding processes. To demonstrate the effectiveness of the proposed strategy, an example is provided of a bearing disc of the type 81212 made of 100Cr6 steel. The process started with the removal of the defect area at the bearing by turning. The groove was then filled by laser-based directed energy deposition (L-DED). A wear-resistant steel containing chromium, nickel, and vanadium was employed as the cladding material as part of a tailored forming method. This type of repair represents a novel approach, where the goal is to realize new ways to produce load-adjusted hybrid solid components. One challenge encountered in processing this high-alloy steel was the presence of welding defects through the repair process. To optimize the quality, a preheating process based on induction was introduced, which led to a significant reduction of defects by 88.3% based on a scanning ultrasonic microscopy analysis. After the geometric contour was restored through machining, a heat treatment was applied, leading to a modification of the carbides and a more refined microstructure. This was found to significantly increase the hardness of the base material by 109% resulting in 780 HV0.1 and the cladding by 8.3% resulting in 753 HV0.1, bringing it into a range similar to that observed prior to the repair (803 HV0.1).