Ball mill is the major equipment pulverized solid materials in many
industrial sectors such as metallurgy, coal, building materials, chemicals,
electricity, etc. Forged grinding balls and gringding rods are two primary grinding media. According to statistics, the annual worldwide consumption of steel balls is
3000-5000 tons. Below we select a few major countries and regions to learn the
abroad application status for steel ball.
1.Japan
In Japan, there are four primary types of steel balls.
Wherein forged or rolling medium-carbon steel ball hardened and heat treated
for use. However, the ball and ordinary white cast iron ball are free or contain
only small amounts of alloying elements, resulting in big hardness difference
between the ball surface and core. Therefore, the wear speed will increase when
the ball get samller by wear, but it won’t crack and peel due to increased
toughness.
Low&medium and high chrome cast ball contain more alloy elements with
good hardenability and little hardness difference between surface and core. It
has good uniform wear rate and wear resistance but prone to surface peeling and
cracking. Generally, wear resistance and toughness for high chrome ball is
better than low chrome ball, it is commonly used for large and medium-sized
cement mill and raw mill, while low chrome ball is more used for coal pulverized
mill. Below table lists the primary composition and performance for Japan steel
balls.
2. The United States and Canada
Steel balls used in the United States and Canada are also divided into four
types.
Wherein the microstructure of nickel-hard cast iron ball is M + K, it looks
like reticular structure with good wear resistance, poor toughness and high cost
(high Ni content).
Medium carbon low alloy steel ball has high surface hardness, when the ball
diameter is large, the wear speed will increase in later period, so it usually
use ball less than 60mm.
The microstructure of high-carbon low-alloy steel ball change to M + K
through 920 ℃ quenching and 230 ℃ tempering, its abrasion resistance is better
than the medium carbon low alloy steel ball.
Because of high content of alloying elements and good hardenability, the
hardness for high carbon high alloy steel ball in surface and core are almost
the same. In production, 70mm balls are more used.
Below table lists the balls major components and performance for the US and
Canada steel ball.
