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Relationship between steel balls and temperature
Release time:
Jul 28,2023
Today we systematically summarize the temperature of forged rolled steel balls in the production process and the importance of steel balls.
1. The main control point of forged rolled steel balls is the temperature of steel balls.
In the production process of steel balls, temperature is always an important quality control point. Temperature control plays a very important role in forging and rolling heating, isothermal waiting for heat treatment, tempering and tempering after storage, and even affects the metallurgical organization of steel balls.
Second, the analysis of the heating conditions.
1. Problems caused by high temperature:Oxidation-overcooking, resulting in the internal structure of the steel ball coarse, unstable, asymmetric and uneven hardness, physical toughness impact value is low, and even up to about 3J/cm2.
The heating of round steel, for example, to do the following explanation: round steel in the heating to 550-600 degrees before the oxidation rate is slow, to 700 degrees above the rapid rise; assuming that 900 ℃ before the oxidation rate of 1, 1000 ℃ for 2, 1100 ℃ for 3, 1300 ℃ for 7 (the following chart)
Forging temperature:980-1080℃;
Rolling temperature:950-1050 degrees;
Scale - iron tetroxide, iron tetraoxide, etc.
Note:No.45 steel is carbon structural steel, above B2 steel is combined steel (alloy structural steel).
(1), oxidized skin is not only produced in the heating process, but also in the forging process;
(2) The longer the heating time, the more scale;
(3). Solution:Heat quickly and reduce the heating time.
2. Problems caused by too low a temperature:Generally speaking, the quenching is impenetrable, regardless of the surface hardness or core hardness, HRC is not up to the required range of values, which leads to the steel ball in the ball mill after the actual operation is not wear (partial wear), or even fracture.
3. Heating furnace impact: heat energy conversion is different, medium frequency induction heating fast, but burn impermeable, commonly known as “hard fire”. For example, the heating of viscous steel appears to be in 1000 degrees, but the actual forging will have a great deal of elasticity, is not conducive to forging; but the same material, after the coal furnace, natural gas furnace, oil furnace heating will be easy to burn, commonly known as “soft fire”. The heating process of “soft fire” has a preheating, high temperature and other slow processes.
Third, the relationship between mill temperature and steel ball.
1. The mill is divided into dry grinding and wet grinding, which is also the distinguishing feature between cast steel balls and forged steel balls.
2. When the mill is running, overhauling or replacing the liner, all the steel balls in the mill need to be poured out, which requires attention to the changes in the temperature of the steel balls, especially the combination of steel balls. If the temperature of the running steel balls drops significantly (or a large amount of water injection is used), surface peeling, skinning or even direct crushing will occur.
Steel ball manufacturers
4. Why should forged steel balls be tempered?
1. As far as the performance of steel balls is concerned, when the temperature of forged and rolled steel balls after quenching is lower than 30 ℃ (can be taken directly by hand), internal stresses have been generated, resulting in the use of steel balls in the use of a lot of problems, such as breakage, surface peeling. Only by quickly reheating the quenched steel ball to the tempering temperature range and eliminating the internal stress can the whole production process be completed successfully and the breakage rate be reduced;
2. Rapid tempering measures:Tempering temperature control range of 180-200 degrees (plus or minus 20 degrees), special specifications and materials of steel balls after special treatment;
3. Factors causing pressure:Iron baskets, iron drums, ground, humid air, etc.. The important two points are:First, if the residual temperature tempering method, steel ball quenching, tempering temperature can not be too low, not less than 40 degrees; Second, tempered steel ball into the warehouse, pouring into the warehouse temperature should not be too high, should not be higher than 120-140 degrees. This high and low are two important nodes. Tempering should be carried out at a lower temperature, the furnace time should be extended. It is necessary to ensure that the steel balls wear back (e.g., 4 hours for normal and 6 hours for low temperatures); when the storage temperature is higher, it will generate stresses again, leading to the crushing phenomenon mentioned above.
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