Steel shot is a spherical object made of metal. The domestic unified standard GBT 18838.3-2008 is used, and the international standard is the American SAE standard. All diameters are nominal sizes.
Common classifications:
1. High carbon steel shot: also called cast steel shot (carbon C content 0.8-1.2%), which is what we usually call steel shot. This type of steel shot is also the first generation of steel shot (cast iron shot is classified as iron shot here). The advantages of high carbon steel shot are simple process and low cost. The disadvantage is that there will be pores (professional steel shot manufacturers will keep the pores below the national standard, which is 10%), burrs, irregular shapes, and cracks (cracks cannot be seen with the naked eye and need to be viewed with a high-power magnifying glass)
2. Low carbon steel shot: generally with a carbon content of 0.2 or more Generally speaking, compared with high carbon, low carbon steel shot has a relatively complex process and better raw materials. Low carbon steel shot is 2 times more resistant to fatigue than high carbon steel shot (laboratory data). However, the production cost of low carbon steel shot is higher. In terms of single smelting, low carbon steel consumes more electricity than high carbon steel. Low carbon steel shot has lower hardness than high carbon steel shot, but stronger toughness. Therefore, low carbon steel shot is more "economical" than high carbon steel shot. Generally speaking, in terms of production cost, although the price of low carbon steel shot is higher than that of high carbon steel shot, the cost of using low carbon steel shot is lower.
3. Chromium-molybdenum alloy steel shot: There are chromium and molybdenum in the chemical composition. In actual production, chromium iron and molybdenum iron are added separately, and raw materials containing chromium-molybdenum alloy are used. Because there is no requirement for the content of chromium and molybdenum in the steel shot standard, and the price of chromium and molybdenum is relatively expensive, the price is higher. Generally, few companies use it. The raw materials used are basically bearing steel sand (environmentally friendly reinforced steel sand), which also contain chromium and molybdenum. This article mainly talks about steel shot, so I will not introduce it in detail.
4. Non-standard steel shot: steel shot that uses inferior raw materials and does not meet the chemical composition standards, which is exactly the opposite of the national standard steel shot we usually say. It is commonly produced in some small workshops, but it has obviously decreased a lot in recent years.
5. Recycled shot: steel shot, steel sand, or wire cut shot used by customers, which are recycled and screened and processed, and are uniformly called recycled shot after packaging. This kind of steel shot is of poor quality because it contains more impurities.
6. Aviation steel shot: used in aerospace and military-type enterprises, the standard is AMS24311 or AMS24312, the hardness is 45-52HRC for ASR series, and 55-62HRC for ASH series, respectively, and the quality requirements for the steel shot itself are very high.
7. Strengthened steel shot: The hardness is higher than that of ordinary steel shot. The hardness is customized according to customer needs. The general hardness is concentrated in 55-62HRC. It is generally used to process gears and springs. This kind of steel shot is more brittle because of its high hardness, and its toughness will be worse than that of ordinary low-carbon steel shot and stronger than that of high-carbon steel shot.
8. Ultrafine steel shot: Most of them have a hardness of more than 60HRC and a particle size of less than 0.15mm. The output is very low, the market demand is low, and they are generally customized and very expensive.
9. Cut wire shot (ground forged steel shot): Here we are talking about a new generation of cut wire shot, also known as ground forged steel shot. Ordinary cut wire shot is too different because of different raw materials, so we will not discuss it here. Ground forged steel shot is a steel shot made by cutting high manganese steel wire into a cylinder at high speed and then grinding the angle. This kind of steel shot has no pores, no cracks, no breakage, long service life, low cost, and high hardness.