Hybrid cylindrical roller thrust bearing washers of type 81212 were manufactured by tailored forming. An AISI 1022M base material, featuring a sufficient strength for structural loads, was cladded with the bearing steel AISI 52100 by plasma transferred arc welding (PTA). Though AISI 52100 is generally regarded as non-weldable, it could be applied as a cladding material by adjusting PTA parameters. The cladded parts were investigated after each individual process step and subsequently tested under rolling contact load. Welding defects that could not be completely eliminated by the subsequent hot forming were characterized by means of scanning acoustic microscopy and micrographs. Below the surface, pores with a typical size of ten µm were found to a depth of about 0.45 mm. In the material transition zone and between individual weld seams, larger voids were observed. Grinding of the surface after heat treatment caused compressive residual stresses near the surface with a relatively small depth. Fatigue tests were carried out on an FE8 test rig. Eighty-two percent of the calculated rating life for conventional bearings was achieved. A high failure slope of the Weibull regression was determined. A relationship between the weld defects and the fatigue behavior is likely.

This study investigates the wear behavior of additively welded cladding layers on less wear‐resistant base materials using plasma‐transferred arc welding and laser hot‐wire cladding. The cladding layers are made from atomized AISI 52100, AISI 5140, and a stainless steel with (0.52 wt% C, 0.9 wt% Si, 14 wt% Cr, 0.4 wt% Mo, 1.8 wt% Ni, 1.2 wt% V, bal. Fe) on unalloyed steel AISI 1022M as the base material. The specimens' microstructure and surface hardness are comparable with conventional specimens of monolithic AISI 52100 and AISI 4140, which is used as a reference. Tribometer tests are carried out in ball‐on‐disk configuration to investigate the wear resistance of the specimen. The multimaterial specimens show comparable wear behavior to their monolithic counterparts, and a good performance of the stainless specimen in pure sliding is proven. These findings suggest that additive manufacturing processes can be used to clad less wear‐resistant base materials and achieve high wear resistance, making it possible to exploit the advantages of surface coatings under severe wear conditions.

The service life of rolling contacts is dependent on many factors. The choice of materials in particular has a major influence on when, for example, a ball bearing may fail. Within an exemplary process chain for the production of hybrid high-performance components through tailored forming, hybrid solid components made of at least two different steel alloys are investigated. The aim is to create parts that have improved properties compared to monolithic parts of the same geometry. In order to achieve this, several materials are joined prior to a forming operation. In this work, hybrid shafts created by either plasma (PTA) or laser metal deposition (LMD-W) welding are formed via cross-wedge rolling (CWR) to investigate the resulting thickness of the material deposited in the area of the bearing seat. Additionally, finite element analysis (FEA) simulations of the CWR process are compared with experimental CWR results to validate the coating thickness estimation done via simulation. This allows for more accurate predictions of the cladding material geometry after CWR, and the desired welding seam geometry can be selected by calculating the cladding thickness via CWR simulation.

Additive manufacturing with multi-material design offers great possibilities for lightweight and function-integrated components. A process chain was developed in which hybrid steel–steel-components with high fatigue strength were produced. For this, a material combination of stainless powder material Rockit^® (0.52 wt.% C, 0.9% Si, 14% Cr, 0.4% Mo, 1.8% Ni, 1.2% V, bal. Fe) cladded onto ASTM A572 mild steel by plasma arc powder deposition welding was investigated. Extensive material characterization has shown that defect-free claddings can be produced by carefully adjusting the welding process. With a tailored heat treatment strategy and machining of the semi-finished products, bearing washers for a thrust cylindrical roller bearing were produced. These washers showed a longer fatigue life than previously produced bearing washers with AISI 52100 bearing steel as cladding. It was also remarkable that the service life with the Rockit^® cladding material was longer than that of conventional monolithic AISI 52100 washers. This was reached through a favourable microstructure with finely distributed vanadium and chromium carbides in a martensitic matrix as well as the presence of compressive residual stresses, which are largely retained even after testing. The potential for further enhancement of the cladding performance through Tailored Forming was investigated in compression and forging tests and was found to be limited due to low forming capacity of the material.

In contrast to conventional components made from a single material, hybrid multi-material components allow the production of load-adapted parts with different materials in different structural and functional areas. Hardenable and forgeable steels with a high carbon content are suitable for increasing fatigue and wear resistance and thus an extension of component life. However, materials with an equivalent carbon content of more than 0.6 are considered difficult to weld due to their tendency to crack. This study investigates the influence of the shielding gas coverage on the laser hot-wire cladding process with high carbon cladding material AISI 52100. For this reason, welding tests were carried out with different parameter combinations in a process chamber flooded with argon. The oxygen content in the chamber was less than 500 ppm during the welding process. The claddings welded in the process chamber are compared to the claddings welded in a previous investigation with a commercial shielding gas nozzle for laser deposition welding with wire. The tests conducted showed reduced pore formation and very little sparking. By using a process chamber, the average degree of dilution was reduced from 16.9% to 8.5% and burn-off of alloying elements was reduced. In most cases, high hardness values of 700 HV0.1 to 850 HV0.1 were achieved. The use of the process chamber demonstrates that the shielding gas coverage and therefore the remaining oxygen content have a high influence on the process stability and seam quality when welding high carbon steel. Such a considerable effect has not yet been observed with other commercially available cladding steels.

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).