Cast steel balls
The company's leading products fall into three categories: 1、 Main power industry products; 2、 Special accessories for auxiliary equipment of power station; 3、 Main products of metallurgical mining industry
Cast steel balls can be divided into three categories, including high chrome balls, medium chrome balls, and low chromium balls.
1. High chromium ball quality index
The chromium content of high chromium balls is greater than or equal to 10.0%. The carbon content is between 1.80% and 3.20%. According to the national standard, the hardness of the high chromium ball must not be less than 58HRC, and the impact value should be greater than or equal to 3.0J/cm2. If this hardness is high, the chromium balls must be quenched and tempered at high temperatures. At present, there are two methods of domestic high chromium ball quenching, including oil quenching and wind quenching. If the high chromium ball test hardness is less than 54HRC, it means that it has not been quenched.
2. Quality index of chromium ball
The chromium ball specifies a chromium content ranging from 3.0% to 7.0% and a carbon content between 1.80% and 3.20%. Its impact value should not be less than 2.0J/cm2. The national standard requires that the hardness of the chromium ball should be greater than or equal to 47HRC. To ensure quality, chromium balls should be tempered at high temperature to eliminate casting stress.
If the surface of the steel ball is black and red, it proves that the steel ball has been tempered at high temperature. If the surface of the steel ball still has a metallic color, we can judge that the steel ball has not been tempered at high temperature.
3. Low chromium ball quality index
In general, low chromium balls have a chromium content of 0.5% to 2.5% and a carbon content of 1.80% to 3.20%. Therefore, according to the national standard, the hardness of the low chromium ball should not be less than 45HRC, and the impact value should not be less than 1.5J/cm2. Low chromium balls also require high temperature tempering to ensure quality. This treatment eliminates casting stress. If the surface of the ball is dark red, it indicates high-temperature tempering. If the surface is still metallic, it indicates that the steel ball has not been tempered at high temperature.
Cast steel balls are usually used for large-scale mining of various cement plants, chemical plants, power plants, quartz sand plants, silica sand plants, etc.
Cast steel balls
1. Casting steel ball production process
Raw material inspection - proportioning material - intermediate frequency furnace heating and melting - steel mold pouring - quenching treatment - tempering treatment - testing - packaging
Two. Forged steel ball quality standard testing method
1. The chemical composition of casting high chromium balls complies with the following table. If the following table does not conform, it can be produced according to the customer's requirements.
|code name||Chemical composition (mass fraction), c/o|
2. The nominal diameter and allowable deviation, maximum diameter and minimum diameter of casting high chromium ball shall comply with the provisions of the following table
|Allowable deviation of diameter||+2.0 -1.0||+2.0 -1.0||+3.5 -1.0|
|The difference between the maximum diameter and the minimum diameter||≤1.8||≤2.4||≤3.0||≤3.6||≤4.2||≤4.6|
3. Casting high chromium ball mechanical properties, can be produced according to customer requirements.
|code name||Surface hardness (HRC)||Impact test Ak||Impact fatigue life (times)|
Note: 1. The falling ball impact fatigue test adopts a grinding ball with a diameter of 100mm, and the test results are carried out on a standard height of 3.5 meters testing machine. The number of impact fatigue times of other diameter grinding balls is converted according to him, the following formula. Nx=N*100/D。 N is the number of times.
2. Impact toughness and impact fatigue life indicators are generally not used as delivery basis.
1. The surface of the grinding ball is not allowed to have cracks and obvious pores, slag inclusions, shrinkage holes, cold partitions, wrinkled skin and other casting defects.
2. The surface defects of the grinding ball should conform to the following table
|Nominal diameter||Allowable surface defects are no larger than mm|
|The gate is fleshy||Sand stained area||Local residual split flash||depth||Single hole area||Total area|
Five. Internal quality
No craters, shrinkage, porosity, slag inclusions and other hole defects are allowed on the cut plane through the gate center and spherical center.
Six. Test methods and inspection rules
1. Impact test, using 10mm×10mm×55mm notched specimen cut through gate on the spherical body of the product.
2. When the Rockwell hardness sample is prepared, the surface of the grinding ball is ground into a platform with a grinder and then inspected, and the thickness is 1.5-5mm.
3. Chemical composition inspection, when the amount of melting furnace exceeds 0.5 tons, it should be inspected furnace by furnace; When the melting amount does not exceed 0.5 tons, it is inspected once per shift. If a sample is unqualified, it should be doubled and retested, and if there is still a failure, the furnace is unqualified.
4. For surface hardness testing, samples should be taken from different positions of each batch of heat treatment furnace, and the number of samples should not be less than 5. After inspection, if one cast iron grinding ball is unqualified, it should be re-inspected with double the grinding ball. If there is still one grinding ball that fails, the batch is unqualified.
5. Internal quality inspection, every 100 tons of cast iron grinding balls of the same type, then 1 largest specification of cast iron grinding balls is extracted for inspection. If the inspection is unqualified, the re-inspection should be doubled in the batch, if the chemical composition is qualified and re-heat treatment is allowed, if there is still unqualified, the batch is unqualified.
Wear resistant steel bar / Cast steel balls / Forged steel balls