| Material Grade | Specifications/mm | Chemical Composition wt/% | |||||||||
| C | Si | Mn | Cr | Mo | Ni | V | Cu | P | S | ||
|
Cr5 |
Φ10~130 |
0.8-1.2 |
0.4-0.6 |
0.5-1.0 |
4-7 |
≤1.0 |
≤1.0 |
≤0.3 |
≤0.2 |
≤0.04 |
≤0.04 |
|
Cr10 |
2.0~3.2 |
0.3~1.2 |
0.2~1.0 |
10~13 |
≤1.0 |
≤1.0 |
≤0.3 |
≤0.2 |
≤0.04 |
≤0.04 |
|
|
Cr17 |
2.0~3.2 |
≤1.0 |
0.2~1.0 |
17~19 |
≤1.0 |
≤1.0 |
≤0.3 |
≤0.2 |
≤0.04 |
≤0.04 |
|
|
Cr20 |
2.0~3.2 |
≤1.0 |
0.2~1.0 |
18~22 |
≤1.0 |
≤1.0 |
≤0.3 |
≤0.2 |
≤0.04 |
≤0.04 |
|
|
Cr26 |
2.0~3.2 |
≤1.0 |
0.2~1.0 |
22~28 |
≤1.0 |
≤1.0 |
≤0.3 |
≤0.2 |
≤0.04 |
≤0.04 |
|
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Permissible Diameter/mm |
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Product Brand |
Specifications/mm |
Hardness/HRC |
|
|
|
Cr5 |
Φ10~130 |
≥50 |
≥3.5 |
M+C |
|
Cr10 |
≥58 |
≥3.5 |
M+C |
|
|
Cr17 |
≥58 |
≥3.5 |
M+C |
|
|
Cr20 |
≥58 |
≥3.5 |
M+C |
|
|
Cr26 |
≥58 |
≥3.5 |
M+C |
Note: M-martensite, C-carbide
The crushing rate should be less than 1%. (Computation method for determination of fragmentation rate, appendix D)
Cracks and visible casting defects such as pore, slag inclusion, shrinkage, cold isolation and wrinkle are not allowed.
◆ The allowable deviation of ball diameter, roundness and allowable surface defects of grinding ball are measured with a scale reading not exceeding 0.1 mm.
◆ Component analysis was carried out according to GB/T 223.
◆ Impulse test is carried out according to GB/T 229 by using 10 mm xl0 mm x55 mm non-notched specimen on the product body as shown in the figure.
◆ Shock impact fatigue life test is carried out according to the method specified in Appendix C of this standard.
◆ The hardness test of 6.5 hardness (HRC) was carried out according to GB/T 230.1. When the sample is prepared, the surface of the ball should be grinded to a flat surface and then inspected. The grinding thickness is 0.2mm-0.5mm.
◆ grinding balls are not allowed to have surface defects. They are inspected by naked eyes.
◆ The numerical modification method is carried out according to GB/T 8170.
◆ The quality of products shall be inspected by the company's quality control department or a third-party inspection institution.
◆ Sampling of grinding balls is carried out according to GB/T 2828.1.
◆ Hardness testing refers to GB/T 230.1 for testing. Specific sampling and testing methods are as follows: 6 grinding balls are sampled in each batch. The core-pulling strip method was used to cut into 10.2 mm *10.2 mm strips and grind them flat to 10 mm *10 mm. A plane was drawn for core, 3/4R, 1/2R, 1/4R and edge HRC hardness test. The hardness values were measured three times at each point and recorded. After inspection, one forged ball is not qualified, and the deviation is less than 95% of the minimum value. Double grinding balls should be allowed for re-inspection. If there is still one unqualified grinding ball, and the average hardness value still meets the requirements of Table 3, it should be judged as qualified, otherwise the batch is unqualified.
◆ grinding balls can be packed in woven bags and barrels.
◆ When transporting in full containers, the type and specifications of balls shall be marked with signs. When packing and transporting, it should be marked on the surface of the package:
✔The name, address and arrival of the demander;
✔ Types and specifications of grinding balls;
✔ packing number;
✔Gross and net quality;
✔Name and address of the supplier;
◆ Each batch of ex-factory products should be accompanied by a quality certificate, indicating;
✔ marks;
✔Types and specifications;
✔ Batch number and batch size;
✔Test results;
✔ Number of this batch.
Appendix C
(Normative Appendix)
Fatigue Life Test Method for Falling Ball Impact .
Falling ball impact fatigue life test (hereinafter referred to as falling ball test) is to simulate the impact process of grinding ball in ball mill under laboratory conditions by using falling ball impact fatigue test machine (hereinafter referred to as falling ball test machine). The number of shocks is recorded by the counter. The number of impact fatigue failures of grinding balls reflects the impact fatigue life of grinding balls under this condition.
✔ The ball dropping machine model is MQ, and the ball dropping height is 10m.
✔The sample of drop ball test is 125 mm grinding ball.
✔ Samples of drop ball test shall be marked on the surface of the replacement ball by taking 16 grinding balls as test balls from the inspection batch and more than three grinding balls as replacement balls.
✔ The ball drop test was carried out at room temperature.
✔ The procedure for judging and testing the failure of cast balls is as follows:
Failure Judgment of A5.1 Cast Ball
◆ The average diameter of exfoliation layer on the surface of grinding ball (the average value of maximum diameter and minimum diameter) is 20 mm to 50 mm, and the thickness of the middle part is 5 mm to 10 mm.
◆ The grinding ball breaks along the middle part.
✔ Test Procedure
✔ Grinds the edges of test balls and replacement balls smoothly or cleans the surface of the cleaning drum. Check the working state of the testing machine.
✔ Firstly, 12 test balls are put into the bend pipe, the test machine is started, and the remaining four test balls are put into the circulating conveying system one by one from the downslide.
✔ Opens the counter, clears the counter, clears the police, and dials the number to the predetermined number.
The A5.2.4 test personnel should observe carefully in the field. When one test ball fails to meet the requirements of a) or B in A.5.1, take out the failure ball and put it into a replacement ball. Until the third failure ball appears, record the cumulative number of shocks in the drop machine system when three test balls fail. If the number of failure balls does not reach the index of number of failure balls, the number of failure balls should not be counted.
