Effect of Nitrogen Ion Implantation on the Cavitation Erosion Resistance and Cobalt-Based Solid Solution Phase Transformations of HIPed Stellite 6

• DOI: 10.20944/preprints202104.0357.v1
• Publication Date: 2021-04-14T11:55:01Z
• Authors: Mirosław Szala; Dariusz Chocyk; Anna Skic; Mariusz Kamiński; Wojciech Macek; Marcin Turek
• Keywords: Stellite; Work hardening

From the wide range of engineering materials traditional Stellite 6 alloy exhibits excellent cavitation erosion (CE) resistance. In this work, effect nitrogen ion implantation HIPed on improvement CE resistance and both cobalt-rich matrix phase transformation due to were stated. The stellites ion-implanted by 120 keV N+ ions two fluences: 5x1016 cm-2 1x1017 comparatively analysed with unimplanted stellite AISI 304 stainless steel. tests conducted according ASTM G32 stationary specimen method. Erosion rate curves mean depth confirm that implanted times exceeds than stellite, has almost 10 higher reference X-ray diffraction (XRD) confirms favours ɛ(hcp) γ(fcc) structure. Unimplanted ɛ-rich matirx is less prone plastic deformation γ consequently, increase effectively holds carbides in cobalt prevents Cr7C3 debonding. This phenomenon elongates three incubation stage, slows mitigates material loss. Metastable structure formed consumes load for work-hardening → ɛ martensitic transformation. further stages, phases transform as namely, cavitation-inducted recovery process, removal strain, dislocations resulting fcc phase. mechanism was investigated using a surface profilometer, atomic force microscopy, SEM-EDS XRD. wear behaviour relies matrix, starting at Cr7C3/matrix interfaces. Once losing their restrain, are debonding removed. Carbides detachment creates pits which initiate cracks propagation through loss proceeds massive chunk materials.