Fe-Si-B čestice praha studirane EBSD analizom područja kod velikog uvećanja

We produced amorphous Fe–Si–B soft-magnetic powder using water atomisation. During annealing the powder particles developed a nanocrystalline structure, and annealing at over 700°C led to the formation of ferrite and boride phases. Here we present a high-magnification electron backscatter diffraction (EBSD) mapping analysis of the powder particles, in combination with a field-emission-gun scanning electron microscopy (FEGSEM) analysis. Some of the problems associated with the preparation of the powder particles for the EBSD analysis as well as the drift problems occurring during the EBSD mapping are reported.Amorfni Fe-Si-B magnetni prahovi su bili proizvedeni vodenom atomizacijom. Za vrijeme procesa žarenja čestice praha dobiju nanokristaliničnu strukturu. Žarenje iznad 700 °C prouzroči nastanak feritne i boridne faze. U ovom članku je prikazana EBSD analiza područja kod velikog uvećanja prašnih čestica u kombinaciji s FESEM. Istaknuti su problemi pripreme čestica praha za EBSD analizu kao i problem pomicanja uzorka tokom EBSD analize

Charpy udarna žilavost i tvrdoća odžarenog materijala i donjeg bainita

A high strength low alloyed (HSLA) V-Nb steel was heat treated to martensite and lower bainite with different grain size, reheated for 3 seconds at 750 °C and air cooled. Charpy notch tests were performed from -100 °C to 60 °C and the hardness assessed at room temperature. For as delivered steel and lower bainite, the upper shelf toughness was above 200 J and the transition temperature low, while, for martensite the upper shelf toughness threshold was aproximateky at 0 °C. After reheating, notch toughness was decreased moderatly for martensite and strongly for lower bainite. Independently on grain size, lower bainite was more propensive than martensite to embritlement after short reheating in the (α + β) range. For martensite, the change of notch toughness was not related to change of hardness, as by lower hardness lower, also toughness was lower.Nisko legirani V-Nb čelik visoke čvrstoće (HSLA) je toplinsko obrađen na martenzit i bainit sa različitom veličinom zrna, odžaren 3 sekunde na 750 °C i ohlađen na zraku. Chapy žilavost je određena u intervalu od -100 °C do 60 °C, a tvrdoća kod sobne temperature. Kod čelika sa početnom mikrostrukturom čelika i donjeg bainita, je bila veoma visoka žilavost iznad 200 J i tranzicijska temperatura niska, dok je bio kod martenzita prag približno kod 0 °C. Poslije odžarivanja se je žilavost smanjila malo kod martenzita i jako kod bainita. Nezavisno od veličine zrna, donji bainit je bio mnogo osetljiviji na pojavu krtosti poslije kratkog odžarivanja u području (α + β). Kod martenzita, promjena žilavosti nije u vezi za tvrdoćom, jer kod niže žilavosti je niža i tvrdoća

Fe-Si-B čestice praha studirane EBSD analizom područja kod velikog uvećanja

We produced amorphous Fe–Si–B soft-magnetic powder using water atomisation. During annealing the powder particles developed a nanocrystalline structure, and annealing at over 700°C led to the formation of ferrite and boride phases. Here we present a high-magnification electron backscatter diffraction (EBSD) mapping analysis of the powder particles, in combination with a field-emission-gun scanning electron microscopy (FEGSEM) analysis. Some of the problems associated with the preparation of the powder particles for the EBSD analysis as well as the drift problems occurring during the EBSD mapping are reported.Amorfni Fe-Si-B magnetni prahovi su bili proizvedeni vodenom atomizacijom. Za vrijeme procesa žarenja čestice praha dobiju nanokristaliničnu strukturu. Žarenje iznad 700 °C prouzroči nastanak feritne i boridne faze. U ovom članku je prikazana EBSD analiza područja kod velikog uvećanja prašnih čestica u kombinaciji s FESEM. Istaknuti su problemi pripreme čestica praha za EBSD analizu kao i problem pomicanja uzorka tokom EBSD analize