If differentiated from the point of view of the production process, grinding balls can be divided into two categories: forged steel balls and cast steel balls. Among them, the forged grinding steel ball is a grinding steel ball that is manufactured by direct high-temperature forging. It does not require melting and casting, but the round steel is called forged steel balls after being forged.
Under normal circumstances, forged grinding steel balls containing 0.1% to 0.5% of chromium, carbon content of 1.0% or less and the ball made of high temperature forging, forged grinding ball surface hardness can reach ≥ 56 or more, normal conditions Forged steel balls often use water quenching.
Forged grinding steel ball can also be subdivided according to different angles, in addition to the more common 45 # steel, 60 Mn, 75 MnCr; can also be divided into fully automatic roll forged steel ball and air hammer forged steel ball, they have different characteristics Suitable for different occasions.
In the production of cast grinding steel balls, it is necessary to heat the waste materials such as scrap steel and scrap iron by heating with an intermediate frequency electric furnace to fully melt the charge. During the melting process of the charge, an appropriate amount of noble metal alloy is added to the furnace for chemical composition adjustment. After the temperature of the molten iron reaches 1550°C or more and the requirements of the process are met, the qualified molten iron is poured into the steel ball mold or steel ball production line mold.
It is easy to understand that the cast grinding balls are produced by casting smelting. The national standards stipulate that the chromium content is ≥10.0%, and the carbon content is between 1.80% and 3.20%. These are called high-chromium alloy cast grinding balls; Standard requirements High chromium ball hardness must be ≥ 58 or more, impact value ≥ 3.0J/cm2, if the hardness of the high chromium ball must be high temperature quenching + tempering.
In other words, the cast grinding steel balls can be classified according to the amount of chromium contained. The products obtained are ultra-high chromium grinding steel balls, generally having a chromium content of >15%. The high chromium casting grinding balls are generally >10%. Chromium content; medium chromium cast grinding balls, generally 5%-7% chromium content; low chromium cast grinding balls, generally 1%-3% chromium content.