Application of computer image analysis software for determining incubation period of cavitation erosion – preliminary results

Abstract

Abstract. The paper discusses the application of image analysis software ImagePro Plus and MetIlo for assessing cavitation erosion wear. The investigation of cavitation damage is performed on a vibratory test rig in compliance with the ASTM G32 standard using the stationary specimen method. Low-alloy steel grade 34CrNiMo6 is used as the test material. Cavitation wear is evaluated by gravimetric and roughness measurements, microscopic observations and computer image analysis in specified exposure times. The computer image analysis of selected surface areas during a predetermined exposure to cavitation time is performed using images captured with a metallographic microscope. Based on the results of scanning electron and stereoscope microscopic observations, the cavitation worn surfaces are qualitatively described. The relations between surface topography, gravimetric measurements and the microscopic results are discussed. The findings obtained by gravimetric and roughness measurements, image processing and microscopic observations are complementary. The results prove the suitability of image analysis for investigating incubation period of cavitation erosion. The quantification of cavitation erosion damage indicates that the incubation period of cavitation erosion of the tested steel lasts for 20 minutes. The results demonstrate that cavitation-worn surfaces at the initial stage of cavitation erosion can be examined using both ImagePro Plus and MetIlo.

Cavitation Erosion Resistance and Wear Mechanism Model of Flame-Sprayed Al2O3-40%TiO2/NiMoAl Cermet Coatings

“…The analysis of the cavitation erosion curves and damaged surfaces of the reference samples (Figures 7 and 8) allows us to state that the tested aluminium alloy exhibits an accelerated stage of erosion, while the FeC and CuZn samples show an incubation period of cavitation. The wear mechanism of AlSi was discussed in detail in our previous work [29]. It is known that the fine grain structure of wrought metal alloys has a beneficial influence on their resistance to cavitation erosion.…”

“…In the cavitation erosion process, the acceleration and deceleration stages of erosion can be distinguished. These stages occur especially during the testing of metal alloy samples according to ASTM G-32, with the incubation stage easily distinguishable [26,29,30]. On the other hand, the process of ceramic material wear differs from that observed for metal alloys.…”

Cavitation erosion and sliding wear resistance of HVOF coatings

“…5) allows to observe different wear mechanisms for each of the tested materials. Steel 304 shows cavitation erosion plot typical for metal alloys recorded in the literature [17,22,23]. However, the process of cavitation erosion of HVOF coatings began without a clear incubation period of cavitation erosion (characteristic for metal alloys).…”

Cavitation Erosion and Sliding Wear Mechanisms of AlTiN and TiAlN Films Deposited on Stainless Steel Substrate

“…Worn surface roughness was measured with an optical profilometer and examined by the SEM-EDS method and optical microscopy (OM, stereoscope microscope Nikon SMZ 1500) (Tokyo, Japan). The cavitation-worn area was measured with the ImagePro computer image analysis software (Media Cybernetics, Inc., Rockville, MD, USA) and captured as OM images [28]. During 4.5 h of cavitation, normalized cavitation erosion resistance was calculated by dividing the estimated indicators of SS304 by estimated indicators of the AlTiN and TiAlN films, based on the results of sample weighing (mass loss), computer image analysis of worn surfaces (% of the damaged area) and surface roughness (roughness parameter Sa).…”

“…In general, the comparison of the worn surfaces agrees with the quantitative data presented in Error! Reference source not found.. As a result of cavitation, the sample surfaces are randomly degraded due to the impact of micro-jets or shock pressure waves [28,34,35]. The TiAlN coating is severely more damaged and shows the presence of more pits in its structure than the AlTiN film (Error!…”