Ultrafine Ductile and Austempered Ductile Irons by Solidification in Ultrasonic Field

Abstract In this research, ultrasonic melt treatment (UST) was used to produce a new ultrafine grade of spheroidal graphite cast iron (SG iron) and austempered ductile (ADI) alloys. Ultrasonic numerically simulated evaluated based on acoustic wave streaming. The simulation results revealed that the streaming waves propagated as stream jet in molten SG along centerline source (sonotrode) with maximum speed 0.7 m/s gradually decreased zero at bottom mold. metallographic analysis newly developed alloy showed an extremely structure. nodules’ diameter ranging between 6 9 µm total nodule count 900 more than 2000 nodules per mm 2 , has never been mentioned literature for castings same diameter, i.e., 40 mm. addition, fully ferritic matrix observed all UST irons. Further austempering heat treatments were performed different grades ausferrite morphologies. dilatometry studies ADI alloys time required completion formation four times shorter statically solidified SEM micrographs fine short structure together small austenite blocks matrix. A dual-phase intercritically (IADI) also produced by applying partial austenitization intercritical temperature range, where + ferrite phases coexist. IADI alloy, it established introducing free would provide additional refinement ausferrite.