1. Characteristics of inoculation treatment
So far, there is no consensus on the action mechanism of inoculation treatment at home and abroad, but the inoculation treatment of cast iron has the following commonalities:
(1) Furnace front and flow. Inoculation treatment is generally carried out in the furnace
Adding inoculant to the molten iron flow during pre tapping and / or adding inoculant to the molten iron flow during pouring (called “flow inoculation”); The shorter the time from the end of inoculation treatment to casting pouring, the better the effect.
(2) Small amount or trace. The addition of inoculant from a few thousandths to ten thousandths can significantly improve the mechanical and physical properties of cast iron.
(3) Nucleation. The main function of inoculant is to promote the liquid iron to produce a large number of graphite cores during solidification, so as to change the eutectic structure of cast iron.
2. Function of inoculation treatment
(1) Promote graphitization, effectively reduce the white tendency of molten iron and eliminate the white at the thin wall.
(2) Refine eutectic and graphite, reduce the formation of supercooled graphite and its associated ferrite, and obtain medium-sized A-type graphite.
(3) Promote the formation of ferrite and refine pearlite, that is, the structure that should be white mouth or hemp mouth becomes gray mouth structure with finer eutectic group.
(4) Improve the section sensitivity of castings.
(5) Improve the mechanical properties of castings and the machinability of cast iron.