Study On Low Carbon Cast Steel Shot

In this thesis, series of low carbon cast steel shot were successfully obtained by medium-frequency melting and centrifugal atomization technologies and temper were performed. The elemental analysis for these low carbon cast steel shot was performed by determining chemical composition machine. The metallographic structure for casted and tempered low carbon cast steel shot has been determined with electronic microscope. The hardness for casted and tempered low carbon cast steel shot was recorded on micro-sclerometer. The detailed structure and appearance of the low carbon cast steel shot have been detected by X-ray diffraction and TEM (Transmission Electron Microscope). The ERVIN life for casted and tempered low carbon cast steel shot were determined by ERVIN test machine, theoretical analysis were dong too. The results show that the diameter of steel stream was 16mm, the flow velocity of steel stream was 100kg/min, the point of pouring was 1600°C, the revolution of electric machine was 1200r/min, 12～25mesh of the low carbon cast steel shot share in total was 72.9%, 30～45 mesh of the low carbon cast steel shot share in total was 10.4%, 7～10 mesh of the low carbon cast steel shot share in total was 14.2%, the chemical composition of the low carbon cast steel shot was C:0.14, Mn:1.13, Si:0.38, S:0.046, P:0.018, HRC45.8, all perfomance meet standard of ISO11124-4 and SAE J2175, the metallographic components of low carbon cast steel shot were carbon-free bainite and low carbon lathed martensite.The diffraction pattern calibration of low carbon cast steel shot uncovered that the orientation relationships between martensite and austentite were classical western hills relationship and bain relationship. The cast ERVIN life is 2671 times, The main defects for low carbon cast steel shot are heteromorphism, voids , impurity, cracks, occluded foreignsubstance, shrinkage and precipitate.The research results also revealed that when the granularity was steadily lowed, the ERVIN life was also gradually increased. The ERVIN life for granularity of 2.36～0.50 mm are 3468～2527 times, respectively. The low carbon cast steel shot obtain tempered martensite, tempered martensite and carbon-free bainite, temper troostite, tempered sorbite after tempering ranging from 150℃, 150℃～350℃, 450℃, 450℃～650℃. the ERVIN life is increased to 2929～4632 times and the hardness is reduced to HRC45.6～HRC20 after tempered.The main wear forms for low carbon cast steel shot are surface shedding,central flaking and brittle fracture. Whereas the surface peeling is the ideal wear failure mode for the low carbon cast steel shot with compact and uniform structure and great impact toughness; the main defects effecting the Ervin life of the low carbon cast steel shot are voids and shrinkage.