Production and application of Austenitic high chromium cast ball (2)
2. Matrix structure, mechanical properties, using properties
Through the reasonable design of the chemical composition, strict control of the content of each element, through metal mold casting process and rapid cooling scheme, as-cast austenite, matrix structure, austenite occupied, volume content 55% ~ 70%, carbide content 20% ~ 26% can be obtained.
With austenite, high texture, chromium cast iron grinding ball surface hardness of 44HRC ~ 47HRC, the surface to central hardness, less than 3HRC. The impact toughness of 10mm × 10ram × 55mm impact test block taken from the cast ball body is greater than 5J/CM2, and its value is much higher than that of quenched martensite high chromium, cast ball, and, troostite high, chromium cast ball. Due to the high toughness of the austenite structure, the grinding ball can resist or absorb the impact energy under the condition of high-stress abrasive impact wear to prevent the occurrence and propagation of the crack, prevent the crack, and spalling of the cast ball, and reduce the wear consumption.
One of the remarkable characteristics of the austenitic high chromium cast ball in use is its work-hardening property. Under high impact force or friction force, the surface layer of the austenitic cast ball under metastable state occurs plastic deformation, which induces the transformation of austenite to martensite in the surface and microstructure of the grinding ball, resulting in a strong work hardening phenomenon, the surface layer of the grinding ball, layer hardening, hardness, than before the use of sharply increased. According to the impact friction energy, the amount is not the same as the surface layer; the hardness is increased by about HRC (5 ~ 15) units at the same time because the core of the grinding ball still retains all the strength and toughness of the austenitic structure, it can restrain the crack propagation and reduce, the cracking and spalling tendency of the grinding balls greatly improves the impact wear resistance of the alloys.
3. Cast balls production
The production of high chromium cast ball adopts 05T medium frequency induction furnace smelting, the main materials are No. 14 pig iron, scrap steel, high carbon ferrochrome, and high carbon ferromanganese, etc. . The casting process was adopted, the casting temperature was controlled from 1500 °C to 1550 °C, and the mould was air-cooled from 650 °C to 750 °C after pouring.
Austenitic, base high chromium cast, the ball can be applied to the diameter of 1.8 m ~ diameter 4 m ball mill, not only in the dry ball mill, the use of excellent performance, but also, because of its austenitic, austenitic structure, magnetic small + corrosion resistance, can also be widely used in a variety of wet ball mill. For example, in an alumina ore with a diameter of 3.2 m × 4m, the consumption of austenitic high chromium ball is 290g/t ore in a wet-type raw material mill. The wear of martensite high chromium grinding ball is 330g/t ore. Therefore, an austenitic high chromium cast ball’s service performance is better than that of quenched martensite ball.
High chromium cast iron grinding balls with austenitic matrix microstructure produced by alloying treatment and permanent mold casting process have the moderate hardness and good toughness, which can better meet the needs of ball mill work, compared with the heat treatment ball, the addition amount of the alloy is less, and the cost is reduced by 200 yuan-400 Yuan per ton, which has excellent wear resistance and economy.