65mn Forged Steel Ball

The Quality Index of the High Chromium Type
The chromium content of the high chromium type product is greater than or equal to 10.0%. And the carbon content is between 1.8% and 3.20%. It is required by the national standard that the hardness of the high chromium type product must be no less than 58HRC, and that the impact value should be greater than or equal to 3.0 J/cm2. This type of products must go through the hot quenching and the tempering treatment to come up to the hardness.


Technological Production Process
Raw Material Inspection - Material Proportion-Intermediate Frequency Furnace Heating and Smelting - Pouring Via Steel Die-Quenching Treatment - Tempering Treatment Inspection - Packaging
Product Quality Standard and Inspection Method
1. The chemical composition of the high chromium type product should conform to the below table 1. We can also manufacture the product with special chemical composition in accordance with the requirements of the customers.

C2.2. The nominal diameter, allowable deviation, maximum diameter, minimum diameter of the cast grinding steel ball should be in accordance with the following table 2.
3. The high chromium type of product can be manufactured with the mechanical properties following the requirements of customers. (table3)

Surface Quality
The surface of the cast iron grinding ball is not allowed to have the casting defects such as the crack, and the obvious gas porosity, inclusion, shrinking cavity, cold shut, elephant skin, etc.
Internal Quality
It is not allowed to have the shrinkage cavity, shrinking porosity, gas porosity, inclusion, and other cavity defects on the section including plane pasting through the pouring gate and the ball center.
Testing Method and Inspection Rules
1. Impact Test
The test is implemented by cutting the product through the pouring gate to get the unnotched specimen of 10mm× 10mm× 55mm.
2. Rockwell Hardness Test Specimen Preparation
3. Chemical Composition Inspection
When the pouring metal amount in the smelting furnace exceeds 0.5t, the personnel should inspect the pouring metal in all the smelting furnaces. When the pouring metal amount in the smelting furnace is less than 0.5t, the personnel can check the smelting furnace one time in each work shift. If one sample is unqualified, the re-inspection should be carried out with the inspection sample doubled. If there is still unqualified sample, then, the pouring metal in this batch of smelting furnaces is unqualified.
4. Surface Hardness Inspection
Take the sample cast iron grinding balls with the amount of no less than 5 from different parts of the treatment furnaces in each batch. After the inspection, if there is one unqualified sample, then take the products randomly with the amount doubled for re-inspection. If there is still one qualified sample, then, this batch of products is unqualified.
5. Internal Quality Inspection
When continuously manufacturing every 100t product of the same type, then select one product with the largest dimension randomly for inspection. If the inspection result is disqualification, then, re-inspection with the sample amount doubled should be carried out. If the chemical composition is qualified, this batch of products is allowed to be processed with the heat treatment again. If unqualified product still exists, then, this batch of products is unqualified.