High Chromium ball Quality index:
Chromium content ≥ 10%, carbon content between 1.8%-3.2% is called high chromium ball, national standards require high chromium ball hardness (HRC) must be ≥58 above, impact value ak≥3.0j/㎝2, if the hardness of high chromium ball must be high temperature quenching + tempering treatment (at present, the domestic high chromium quenching oil quenching and wind quenching two quenching methods), such as detection of hardness (HRC) less than 54 of the following indicates that high chromium ball has not been quenched.
Second, medium chromium ball quality index:
Chromium content 3.0%~7.0%, carbon content between 1.8%-3.2% is called the middle chromium ball, impact value ak≥2.0j/㎝2, the national standard requirements of chromium ball hardness (HRC) must ≥47 above, in order to ensure the quality of steel ball in the use of high-temperature tempering process (in order to achieve the elimination of casting stress), such as the surface of the steel ball dark red indicates that the product has been high-temperature tempering treatment, such as the surface of the steel ball is still metal color indicates that products do not have high-temperature tempering treatment
III. Low Chromium ball Quality index:
Chromium content 0.5% ~ 2.5%, carbon content between 1.8%-3.2% is known as low chromium ball, national standards require low chromium ball hardness (HRC) must be ≥45 above, impact value ak≥1.5j/㎝2, in order to ensure the steel ball quality low chromium ball also need to adopt high-temperature tempering treatment (in order to achieve the elimination of casting stress), such as the surface of the steel ball dark red indicates that the product has been high-temperature tempering treatment, such as steel ball surface still metal color indicates that products do not have high-temperature tempering treatment
Four, forging ball quality index:
By the different technology made of round steel ball, carbon content under 1%, the quality of the material is very important to the product (alloy element), the surface does not have the pouring mouth, the ball in the grinding process will not appear deformation, is always spherical, the current production process are:
(1) Air hammer forging: more common, but the human cost is higher, and product quality is controlled by human factors, the quality is unstable;
(2) Rotary cutting section: This process only Shandong Hua min Steel Ball co., Ltd. in the use of independent research and development and manufacturing, is the first fully automated forging production line, low human cost and stable product quality, a line of annual production capacity of at least 30,000 tons.
Hardness (HRC) and wear resistance according to the round-bar materials and processes are different, the Chinese steel ball surface hardness can reach more than 60, internal and external hardness difference 1-3 degrees, grinding Ball's overall wear resistance is better than high chromium ball.
Five, wear resistance comparison:
(1) Different genes: forged ball material for high-quality steel, and cast ball material for scrap metal;
(2) Casting ball surface has pouring mouth, sand hole and ring belt, and the surface of the forging ball is smooth, the quality of the ball seriously affects the deformation during the grinding process, and the forging ball is better than the casting ball because of the surface quality.
(3) The impact toughness of the forging ball is greater than 12, and the casting ball is only 3-6, which determines the crushing rate is better than the casting ball.
(4) The casting ball is suitable for grinding machine with diameter of 1.5-3.8m, while the forging ball is suitable for grinding machines with a diameter of 1.5-11m and above.
(5) The casting ball is only suitable for dry grinding, and the forged ball is suitable for its excellent gene-quality steel, which is inherently corrosion resistant and dry and wet.