Recarch Of Preparation Process And Wear Mechanism Of Grinding Balls Used In The Ball Mill

The optimal preparation process of lower bainite ductile iron were determined by researching the influence of casting process and heat treatment process on microstructure and mechanical property. The wear behavior and wear mechanism of lower bainite ductile iron under different service conditions were studied on the basis of impact wear test and corrosive wear test. The best throw trajectory and biggest impact load were analyzed according to study of grinding balls kinematic. The most appropriate service conditions of wear resistant materials were researched by comparing the weight loss characters during wear tests. The results show that:There was closely relationship between the morphology and distribution of graphite and the nodularizing and inoculation treatment. Treating with2.2wt%MgSiRE8for spheroidization,0.8wt%FeSi72for inoculation at1450℃for90s, and1.2wt%FeSi72for inoculation during the casting, the graphite had best size, morphology and distribution. The plastic deformation coordination of lower bainite ductile iron was increased for the higher adhesion strength between spheroidal graphite and matrix, the uniform distribution of fine lower bainite around the spheroidal graphite. All the Jominy specimens had undergone three different heat transfer mechanisms including film boiling mechanism, nucleate boiling mechanism and natural convection mechanism during the Jominy test. The microstructure experienced martensite transformation, bainite transformation, perlitic transformation and ferrite transformation along with the increase of Jominy distance (DJ), on account of different cooling rates. Austenitizing at860℃for2h, continuous cooling in medium at20℃, and tempering at250℃for2h, the lower bainite ductile iron presented property gradient characteristics, which had high hardness on the surface and high toughness inside. The wear mechanism during impact wear test gradually varied from plough wear to micro-cutting wear and fatigue wear. The main corrosion wear mechanism were chemical corrosion, galvanic corrosion and plough wear mechanisim, and the weight loss rates of impact wear, abrasive wear and corrosion wear all increased sharply with the test load. However, the abrasive resistance of lower bainite ductile iron was increased obviously for the martensite transformation from retained austenite during the impact wear test. In addition, the lower bainite ductile iron was appropriate for service condition with high impact load and lower acidity; the high-chromium iron was suitable for service condition with lower impact load and lower acidity; the low chromium iron was appropriate to apply to small dry ball mill or medium dry ball mill; However the70Mn martensite steel was applied to medium dry ball mill suitablely.