Janusz Steller

International Cavitation Erosion Test and quantitative assessment of material resistance to cavitation

Abstract In September 1987, during the ELSI VII Conference, the start of the International Cavitation Erosion Test (ICET) project was announced. The experimental programme consisted in testing 6 selected materials (single-phase aluminium and brass alloys, Armco iron, carbon and chromium–nickel steel, and a polyamide 6 plastics) at various laboratory rigs. Tests were conducted at 4 cavitation tunnels, 4 rotating disks, 6 vibratory rigs, 1 liquid jet and 2 cavitating jet facilities. The results, now available in form of a MS Access database and the ICET Preliminary Report, convince that in addition to standardisation of selected experimental techniques, one should strive to develop methods allowing to predict material performance under variable cavitation loading conditions. In the present contribution, a method of quantitative material resistance assessment based on an idea of defining response to individual fractions of cavitation pulses histograms is proposed. Cavitation pulses are classified as micro- and macro pulses, depending on the affected area size, and divided into amplitude fractions. Erosion due to individual fractions is assumed to follow the same general law Δ V = A · ME i · U ( k i , E ) with A the eroded area, ME i the power flux delivered to a unit area of impinged surface, E the cumulative energy delivered to this area, and k i the material resistance vector consisting of parameters of the erosion progress function U . The erosion progress due to the polyfractional cavitation impingement is assumed to follow a superposition law described by a differential equation presented in the paper. Advantages and weakpoints of the approach are discussed.

The influence of residual stresses on cavitation resistance of metals — an analysis based on investigations of metals remelted by laser beam and optical discharge plasma

Abstract An analysis of the changes of residual stresses in metals as well as analysis of their performance under cavitation conditions contributed to enlight the problem of the influence of residual stresses on metal resistance to cavitation attack. The samples destined for testing were processed superficially with c.w. CO2 laser beam or an optical discharge plasma; afterwards they were subjected to cavitation erosion in the rotating disk facility. Residual stresses were determined by interferometric methods.

Cavitation resistance of new chromium–manganese and chromium–cobalt electrodes and their metallographic structures

Abstract The aim of this paper is to describe the influence of chemical composition of the padding welds on the chromium steel samples (steel 2H13) on their performance under cavitation attack. The chemical composition of the padding welds assured their austenitic or martensitic structure. The superficially processed workpieces were subjected to cavitation impingement at the rotating disc. Close relationship between the padding welds chemical composition, their structure and resistance to cavitation has been proved.