5.5.1. Screening Test

First, a hybrid bearing washer with AISI 52100 cladding was tested on the FE8 test rig with 40 kN at 250 min−<sup>1</sup> (*pH* = 1.85 GPa, κ = 0.55), in accordance with previous investigations [13,14]. In these investigations, maximum running times until failure of 260 h for a cladding with a martensitic chromium-silicon steel (AISI HNV3, 1.4718), and 332 h for a cladding with AISI 5140, were achieved.

The tailored forming washer with AISI 52100 cladding, on the other hand, ran 1100 h without a critical damage event. After this, the test was aborted and considered passed. The test was interrupted every 100 to 200 h to document the possible progression of the damage. The disc was extracted and examined visually, microscopically, and by means of SAM, see Figure 13. After 400 h, a surface defect with a maximum depth of 2.6 μm was detected.

The form of damage is unusual for damage that could have occurred during operation of the rolling bearing. It is more likely to be associated with a scrape mark during reassembly of the test. However, it is noticeable that this damage did not lead to the failure of the bearing. Even by means of ultrasonic microscopic images, no damage could be detected below the surface during continuous testing.
