Boleslaw G. Giren

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 erosion of some alloys manufactured on steel and iron surfaces by laser beam

Cavitation erosion resistance of structural carbon steel, corrosion resistant chromium steel and technical iron superficially processed by CO2 laser beam were investigated. Various metallic powders had been alloyed on the surfaces of the samples and then subjected to cavitation at the rotating disc facility. Tests were carried out in the incubation period of the erosion. It was found that material of reduced ability to work hardening could not achieve optional resistance to cavitation, regardless of its hardness. Moreover, strong dependence of the increase in erosion resistance of the alloyed materials on the substrate was also observed. The best performance under the erosion conditions displayed the samples alloyed with AlNi and SiC or with Nb powders. In each case mentioned, high increase in surface hardness was achieved due to cavitation loading.

Cavitation resistance of 45 and 2Cr13 steels enriched with laser-deposited Hf, SiC, or SiC+AlNi powders

Cavitation resistance of 45 and 2Cr13 steels with surface layers enriched with Hf, SiC and AlNi was investigated. Each doped element was spread over the sample surface and subsequently melted with core material using CO2 laser beam. The cavitation tests carried out at the rotating disk facility revealed multiple (5-10 fold) increase of erosion resistance of the processed materials. This effect was not always related to observed changes of microhardness. Moreover, both microstructure of the surface layer and of core material were found to influenced cavitation erosion resistance.

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.

Search for CO2 laser beam parameters affecting the process of the laser elevating of cavitation resistance of steels

The influence of high power CO2 laser beam parameters on the process of the laser elevating of cavitation resistance of steels was investigated. The samples of structural carbon steel and corrosion resistant chromium steel were melted superficially with the laser beam and subsequently subjected to the cavitation loading. It was discovered, that the power distribution in the cross section of the laser beam was of the great importance for the elevating of the cavitation resistance of the steel surface subjected to the multipath scan processing. The dependence of the erosion resistance of the tested materials on the frequency of the laser pulses as well as on the power of the beam was also discussed.

Cavitation resistance of 0H18N9T steel alloyed with various amounts of TiC or Mn by means of laser beam

An influence of laser beam surface alloying of 0H18N9T chromium-nickel austenitic steel with various amount of Mn or TiC powders on its performance under the cavitation erosion conditions was investigated. The samples of various contents of the additives were tested. The powders of alloying elements were melted by means of CO2 laser beam, and subsequently subjected to cavitation loading at the rotating disc facility. It was found, that presence of manganese increases capability of the substrate to work hardening and slightly contribute to an increase in its erosion resistance. It was also found, that small content of the TiC in the surface layer of the 0H18N9T steel leads to considerable increase in its hardness, unfortunately accompanied with considerable increase of the brittleness. Moreover, the quality of the melted paths produced in one step process were very poor due to appearance of the forging pores. The latter effect made the obtained coating useless for the purposes of the improving were properties of the investigated steel.

Some coatings of high cavitation resistance produced by CO2 laser beam

An influence of laser beam surface alloying of such substrates as Armco iron as well as the structural carbon steel (45) and the corrosion resistant chromium steel (2Cr13) on their performance under the cavitation erosion conditions was investigated. The powders of various additives were melted and alloyed by means of CO2 laser beam, and subsequently subjected to cavitation loading at the rotating disc facility. As a result of assays carried out four coatings of high (Co) or contributing to the increase in the impact toughness (Ni, Mn) were indicated as the responsible for the substantial improvement of the material wear properties.