CNC Knowledge: 12 factors influencing distortion of the heat treatment of equipment

1. Steel carbon content
The carbon content has the greatest impact on the distortion of the warpage and the volume during the caliber.

2. Steel alloy elements
Steel alloy elements have a great influence on the distortion of gears, such as alloy elements C, MN, Ni, CR, MO, etc., increase sustainability and increase the trend of distortion; MN, MO, Si, Ni, Ti, etc. can reduce distortion.

3. Dardenability of steel
The higher the sustainability of steel, the greater the distortion; The smaller the durability, the smaller the distortion of the extinction.

4. Form of the gear and transverse cutting dimensions
The design of the gear has an asymmetrical shape and poor transversal uniformity; the rigidity of the design of the gear;

5. The original steel structure
1) The inhomogeneity of the steel microstructure has a great impact on the distortion of heat treatment. In addition, the microstructure in steel is uneven, the structure is thick, there is a large segregation, a network structure, etc., and the distortion increases after extinction.

2) Due to the existence of defects such as the structure of the belt and segregation, it has become one of the important factors which cause the distortion of the gears.

3) Macroscopic segregation of steel ingots often causes square segregation on the transverse cut of steel, which often causes a distortion of the unequal extinction of discs in the shape of a disc.

4) The distortion of the heat treatment of gears produced in squares of continuous square casting is uniform;

5) The more the size of the essential grains, the quantity of distortion after the extinction of the equipment, will decrease accordingly.

6) If the original structure of the normalization treatment of the gear white is uneven, it will cause distortion of the heat treatment of the equipment.

6. Forger
1) Full forgeage helps reduce distortion. Especially after forging, a reasonable metallic rationalization structure can be formed, which can reduce the distortion of heat treatment. Reasonable forging can also reduce segregation, uniform structure and improve the band -shaped structure, which is conducive to reducing the distortion of heat treatment.

2) When the metal does not fill the cavity of the mold, the final distortion of the heat treatment will be incoherent.

3) When speed whites are forged, the distortion of the heat treatment of the gear will increase due to high temperature heating, the unequal deformation degree and the high final forging temperature.

7. Preparation of heat treatment for whites
1) The preparation of the heat treatment of the whites of the equipment can reduce the final distortion of the heat treatment. When the ordinary standardized fire is used, the distortion of thermal treatment is greater than that of the normalized isothermal fire.

2) The gear white is tempered before the caliber, and the distortion after the extinction is very regular and the absolute distortion will be reduced.

8. Residual stress
The mechanical treatment of gears can cause stresses subject to metal distortion.

9. Soak and heating process
1) Larger diameter or thickness of the maximum stress which can be generated by gears at heating temperatures, causing greater distortion.

2) In many cases of production, the temperature difference between the gears tightened in the furnace is large at the start of the oven, and the thermal stress generated is sufficient to cause a plastic deformation of the part which first reaches a high temperature And causes a local distortion.

3) unequal heating (including rapid heating) has in particular a large impact on the distortion of elongated axial teeth and thin flakes gears.

4) Generally, when the heating is unequal (such as the direct temperature of the heating element), the side of the gear at high temperature inside the gear often seems depressed and deformed after cooling.

5) The heating speed will directly affect the formation of thermal stress during the heating process and thus cause the distortion of the gears.

10. Cooling
1.
The greater the cooling capacity, the greater the intensity of the soil (H), the more the temperature difference between the interior and the exterior of the gear is greater (or the difference in thickness) and the more the constraint generated;
The types, cooling properties, hardening properties of the extinction cooling medium are linked to distortion.

2) unequal cooling
Distortion caused by the structure of the gear, the distortion caused by the tightening of the gear and the distortion caused by the caliber of the characteristics of the coolant.

3) average temperature of caliber
In general, when the temperature of the quenching medium (such as the soil oil) is correctly increased, the distortion of the heat treatment of the gear decreases.

11. Soak operation
1) Tightening and support methods of equipment
When installing speed ovens, tightening and suspension methods, sling tools and their support methods also have a lot to do with the distortion of the gears, in particular outside diameter in addition to the expansion and From contraction, roundness often exceeds the difference. If the furnace is poorly installed, it is very easy to cause a large flipper at high temperature. and distortion.

2) Timing temperature and heating uniformity
The degree of influence of the quenching temperature on the distortion of the warpage is much higher than that of the volume distortion. The increase in the caliber temperature generally increases the distortion of the gears;
Distortion caused by unequal heating.

3) Repeat the extinction
For gears due to the quality of heat treatment exceeding the difference, if the caliber is repeated during the rework process, the distortion will be superimposed as the caliber increases.

4) Effects of extinction and cooling
The gear cooling speed is large and the expansion of the volume occurs at the same time.
Double mediation caliber or implementation of the implementation of the first environment during the first environment;

5) Operational factors
This is often linked to violations of process regulations during operation. For example, the gears crowd and collide with each other during the furnace; , the operation is unstable and the earthquake is large, the gears will be increased; Thin trees and gears are more affected.

12. Temperature, cold treatment and efficient efficiency
1) backfire
The temperature changes in the size of the gear are mainly caused by the transformation of the tissues.

2) Cold treatment
For gears with a high alloy content or precision gears, treatment to the cold at temperature below zero is generally carried out to convert more residual austenite into hammer, thus showing a trend to distortion the increase in size . If the caliber temperature is higher, the more dimensional expansion will appear after cold treatment.

3) Treatment of aging
In the structure of the extinction of the gears, the amount of residual austenitis is the main cause of the distortion of aging. In natural aging, the relaxation of stress is caused by the escape of hydrogen; The release of the relaxation of stress during natural aging can cause a very small amount of phase change to residual austenite.