Cavitation erosion behaviour of laser processed Fe-Cr-Mn and Fe-Cr-Co alloys

Purpose: Purpose of this paper is investigation of influence of the surface processing by laser method on the cavitation performance of the Fe-Cr-Mn and Fe-Cr-Co alloys. This kind of alloys are frequently used in Polish power plants to routine repairs of damaged blades working under cavitation loading. Design/methodology/approach: Padding welds were tested for three cases: without additional processing, after laser heating of the solid state and after laser melting of the coating. Cw. CO2 laser with a beam power 1000 W was used as a source of radiation. The investigated samples were subjected to cavitation loading at the rotating disk facility. The microstructure, chemical composition and phase identification of the modified and subjected to cavitation loading layers were examined using scanning electron microscopy, light microscopy, and X-ray diffractometry, respectively. Findings: Results revealed that structure refinement due to laser processing contributes to delaying of austenite → martensite phase transformation. Kinetic of austenite → martensite transformation is different for investigated alloys and depends on the chemical composition and applied laser processing. Research limitations/implications: Reported research ought to be completed and full cavitation curves (volume loss in time) for processed padding welds must be done. Practical implications: Obtained results indicate that for low intensity of cavitation loading, like in field conditions, laser beam machining can increase of cavitation erosion resistance of investigated alloys due to increase of hardness and structure fine degree. Originality/value: Confirmation that creation of the transformed and hardfacing structures by laser techniques leads in many cases to considerable changes in cavitation erosion properties of the processed materials.