Mikrostrukturne promjene u zavaru dupleks-čelika i njihov utjecaj na otpornost eroziji krutim česticama i kavitacijskoj eroziji

The microstructural transformations which took place during the welding of duplex steel as well as their influence on the resistance to particle erosion wear and cavitation erosion wear were investigated. A sample was cut from a 1.4462 rolled steel plate and heat treated in order to obtain a microstructure which would resemble, as closely as possible, the actual welded microstructure. Qualitative and quantitative microstructural analyses were performed on the samples. The influence of the sigma phase and its volume fraction (obtained by annealing at 800 °C) was investigated, as well as the influence of the various ferrite/austenite ratios (obtained by annealing in the 1100 °C —1300 °C temperature range) on particle erosion and cavitation erosion resistance. It was found that the microstructural transformations which took place in the weld zone and the heat affected zone significantly influence resistance to wear in the investigated cases.U radu je istražen utjecaj mikrostrukturnih promjena, nastalih pri zavarivanju dupleks-čelika, na otpornost eroziji krutim česticama i kavitacijskoj eroziji. Uzorci su izrezani iz valjane ploče dupleks čelika 1.4462 i toplinski obrađeni tako da im se mikrostruktura što više podudara s mikrostrukturom realno zavarenog spoja. Na uzorcima je napravljena kvalitativna i kvantitativna analiza mikrostrukture. Istražen je utjecaj porasta volumnog udjela sigma faze (dobiven žarenjem na 800 °C) te utjecaj porasta omjera ferit/austenit (dobiven žarenjem na temperaturi od 1100 do 1300 °C) na otpornost eroziji krutim česticama i kavitacijskoj eroziji. Utvrđeno je da mikrostrukturne promjene koje nastaju u metalu zavara i zoni utjecaja topline dupleks čelika imaju veliki utjecaj na otpornost trošenju ispitanih slučajeva