Influence of Conventional and Cryogenic Piezo Peening on Bending Fatigue Strength of Hardened Bearing Steel AISI 52100

Author:  Alexander Klumpp, Mehmet Ali Tamam, Florian Vollert, Stefan Dietrich, Volker Schulze
Source:  ICSP-13
Doc ID:  2017109
Year of Publication:  2017
Introduction: Machine hammer peening (MHP) treatments have become a crucial process step in the fabrication of molds and dies, which is mainly due to the generation of smooth surfaces in connection with compressive residual stresses (RS) and work-hardening [1]. Developed at Karlsruhe Institute of Technology (KIT), piezo peening (PP) is a modern MHP treatment capable of generating a large bandwidth of (anisotropic) RS and work-hardening states with penetration depths between 100 μm and 1 mm [2, 3]. By this means, greatly enhanced fatigue behavior could be achieved on quenched and tempered low alloy steel AISI 4140 in previous studies [4]. Fig. 1 shows a schematic representation of the utilized PP device [2]. The spherical hammer head is brought into oscillation by the piezo actuator with specific frequency and stroke. A linear, CNCcontrolled x-y slide is used to define indentation and “stepover” (line spacing e.g. in meanders)distance on the specimen to be treated. These parameters, defining hammer head movement and path, allow for the introduction of RS states with variable maximum amount and degree of anisotropy. A soft bearing on top is used to determine contact properties and allow for load control.By this means, the “load fraction” [3] can be adjusted between non-contact and full contact.

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