The ball mill steel balls on the market can be divided into two types based on manufacturing processes: casting and forging, but their wear resistance is different. Due to the crushing of materials, steel balls require good wear resistance and sufficient toughness. Usually, alloy steel, high manganese steel, cast iron with chromium iron and other materials are forged or cast in one go, and corresponding heat treatment processes are more economical. Ball mill steel balls can be divided into: 1. Forged steel balls: low-carbon alloy steel balls, medium carbon alloy steel balls, high manganese steel balls, rare earth chromium molybdenum alloy steel balls; 2. Cast steel balls: low chromium cast balls, medium chromium cast balls, high chromium cast balls. Which type of steel ball is the best on the market now? Now let's analyze: 1. Forged steel balls: good surface quality, good impact resistance, strong toughness, good wear resistance, not easy to break and lose roundness. It is a processing method that heats the metal to a temperature of 1050 ℃ (plus or minus 50 degrees), applies pressure to the metal billet using forging machinery, and causes plastic deformation to obtain forgings with certain mechanical properties, shapes, and sizes. Forging (forging and stamping) is one of the two major components. Forging can eliminate defects such as casting porosity that occur during the smelting process of metals, optimize the microstructure, and at the same time, due to the preservation of intact metal flow lines, the mechanical properties of forgings are generally better than castings of the same material. In related machinery, important parts with high loads and severe working conditions are often forged, except for simple shaped plates, profiles, or welded parts that can be rolled. In addition, the most wear-resistant materials must be selected for forging steel balls, such as 60Mn and 65Mn according to national standards, or high-efficiency wear-resistant alloy steel materials independently developed by some companies. We use steel produced by national super large steel mills, which are the same material and have varying quality in different steel mills. The quality of forgings depends 80% on the quality of the material, such as using high manganese steel, which has good impact resistance, strong toughness, good wear resistance, and is not easy to break. Forged steel balls are highly favored by users due to their low price, economic durability, and other characteristics. For example, international mining giants such as Rio Tinto, BHP Billiton, and Anglo Gold all use forged steel balls.
Characteristics of forging production:
(1) Forging heated metal materials into various shapes of tools, mechanical parts, or blanks is called forging. Forging can change the internal structure of metal materials, refine their grains, and improve their mechanical properties.
(2) Forging production requires the use of heating equipment, forging equipment, and many auxiliary tools.
(3) Forging equipment mainly includes steam hammers, air hammers, die forging hammers, mechanical hammers, clamp hammers, spring hammers, belt hammers, crank presses, friction presses, machines, hole boring machines, roll forging machines, etc.
Casting steel balls:
1、 Quality indicators for high chromium balls: chromium content≥ 10.0% and carbon content between 1.80% and 3.20% are called high chromium balls, and the national standard requires that the hardness (HRC) of high chromium balls must be≥ Above 58, impact value ak≥ 3.0J/cm2. If the hardness of the high chromium ball reaches this level, it must be quenched and tempered at high temperature (currently, there are two quenching methods for high chromium balls in China: oil quenching and air quenching). If the hardness (HRC) is below 54, it indicates that the high chromium ball has not undergone quenching treatment.
2、 Quality indicators for medium chromium balls: chromium content between 3.0% and 7.0%, carbon content between 1.80% and 3.20% are all called medium chromium balls, with impact values ak≥ 2.0J/cm2, the national standard requires that the chromium ball hardness (HRC) must be maintained; For steel balls above 47, in order to ensure the quality of chromium balls, high-temperature tempering treatment is required (to eliminate casting stress). If the surface of the steel ball is dark red, it indicates that the product has undergone high-temperature tempering treatment. If the surface of the steel ball still appears metallic, it indicates that the product has not undergone high-temperature tempering treatment.
3、 Low chromium ball quality indicators: Low chromium balls with a chromium content of 0.5% to 2.5% and a carbon content between 1.80% and 3.20% are called low chromium balls. National standards require that the hardness (HRC) of low chromium balls must be maintained; 45 or above, impact value ak≥ 1.5J/cm2, in order to ensure the quality of steel balls, low chromium balls also need to be subjected to high-temperature tempering treatment (to eliminate casting stress). If the surface of the steel ball is dark red, it indicates that the product has undergone high-temperature tempering treatment, and if the surface of the steel ball still appears metallic, it indicates that the product has not undergone high-temperature tempering treatment.
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