Surface and Subsurface Analysis of Stainless Steel and Titanium Alloys Exposed to Ultrasonic Pulsating Water Jet

0545824 - ÚFM 2022 RIV CH eng J - Journal Article
Poloprudský, Jakub - Chlupová, Alice - Šulák, Ivo - Kruml, Tomáš - Hloch, Sergej
Surface and Subsurface Analysis of Stainless Steel and Titanium Alloys Exposed to Ultrasonic Pulsating Water Jet.
Materials. Roč. 14, č. 18 (2021), č. článku 5212. E-ISSN 1996-1944
R&D Projects: GA ČR(CZ) GA19-00408S
Institutional support: RVO:68081723 ; RVO:68145535
Keywords : initial erosion stage * 316L * Ti6Al4V * eroded surface topography * water volume droplets * dislocation structure
OECD category: Mechanical engineering; Mechanical engineering (UGN-S)
Impact factor: 3.748, year: 2021
Method of publishing: Open access
https://www.mdpi.com/1996-1944/14/18/5212

This article deals with the effect of periodically acting liquid droplets on the polished
surfaces of AISI 316L stainless steel and Ti6Al4V titanium alloy. These materials were exposed to a
pulsating water jet produced using an ultrasonic sonotrode with an oscillation frequency of 21 kHz
placed in a pressure chamber. The only variable in the experiments was the time for which the
materials were exposed to water droplets, i.e., the number of impingements, the other parameters
were kept constant. We chose a low number of impingements to study the incubation stages of the
deformation caused by the pulsating water jet. The surfaces of the specimens were studied using
(1) confocal microscopy for characterizing the surface profile induced by the water jet, (2) scanning
electron microscopy for detailed surface observation, and (3) transmission electron microscopy for
detecting the changes in the near-surface microstructure. The surface described by the height of the
primary profile of the surface increased with the number of impingements, and was substantially
more intense in the austenitic steel than in the Ti alloy. Irregular surface depressions, slip lines, and
short cracks were observed in the Ti alloy, whereas pronounced straight slip bands formed in the
austenitic steel. The dislocation density near the surface was measured quantitatively, reaching high
values of the order of 1014 m² in the austenitic steel and even higher values (up to 3 1015 m􀀀2) in
the Ti alloy. The origins of the mentioned surface features differed in the two materials: an intense
dislocation slip on parallel slip planes for the Ti alloy and mechanical twinning combined with
dislocation slip for the austenitic steel.
Permanent Link: http://hdl.handle.net/11104/0322624