How to heat treat gears with No. 45 steel?

According to the requirements of the gear: if the impact force is small, the surface carburizing, nitriding and other technologies can be carried out! In this way, the surface hardness is higher, while the matrix hardness is lower, the wear resistance is good, and it is not easy to break.

If the impact load is large, it will be tempered because of the quenching and tempering treatment, that is, high-temperature tempering.

The quenching temperature of the steel is about 580 degrees, and the holding time has a formula, according to your equipment, the size and shape of the workpiece, and then quenched, and then tempered at a high temperature of about 500--600, air cooled, and then air-cooled at 200 degrees in heating, this step is mainly to eliminate stress, and the precision of the gear is guaranteed by him in the future, and then in finishing!

No. 45 steel is quenched and before tempering, and the hardness is greater than HRC55 (up to HRC62) is qualified. The highest hardness for practical application is HRC55 (high-frequency quenched HRC58).

No. 45 steel should not be subjected to the heat treatment process of carburizing and quenching. The quenched and tempered parts have good comprehensive mechanical properties, and are widely used in various important structural parts, especially those connecting rods, bolts, gears and shafts that work under alternating loads. However, the surface hardness is low and not wear-resistant.

Quenching and tempering surface quenching can be used to improve the surface hardness of parts.

Carburizing treatment is generally used for heavy-duty parts with surface wear resistance and core impact resistance, and its wear resistance is higher than that of quenched and tempered surface quenching. Its surface carbon content, the core is generally used in special cases. After heat treatment, the surface can obtain a high hardness (HRC58 62), with low core hardness and impact resistance.

If 45 steel is used for carburizing, hard and brittle martensite will appear in the core after quenching, and the advantages of carburizing treatment will be lost. At present, the carbon content of the materials using the carburizing process is not high, and the strength of the core can be very high, and it is rare to be used in applications.

I've never seen an example, it's only introduced in textbooks. The process of quenching and tempering high-frequency surface quenching can be adopted, and the wear resistance is slightly worse than that of carburizing.

The recommended heat treatment system for 45 steel specified in the GB T699-1999 standard is 850 normalizing, 840 quenching, and 600 tempering, and the performance achieved is 355MPa yield strength

The GB T699-1999 standard stipulates that the tensile strength of 45 steel is 600MPa, the yield strength is 355MPa, the elongation is 16, the section shrinkage is 40, and the impact energy is 39J.

Gear working conditions: steel grade heat treatment process.

The hardness requires working under low loads, and requires gears with high wear resistance 15 (20) 900 950 carburizing, direct quenching or 780 800 water quenching, 180 200 tempering.

58 63hrc low speed (<, unimportant gearbox working at low load.

Gear & Hanger Frame Gear 45840 860 Normalizing.

156 217HRC low speed (<, gears working under low load (such as gears on lathe slides) 45820 840 Water quenching.

500 550 Tempering 200 250HRC Working at medium, medium or heavy loads (secondary gears in lathe gearboxes) 45860 900 High frequency induction heating, water quenching, 350 370 Tempering 40 45 HRC gears operating at large or medium loads, with high tooth requirements (secondary gears in drilling machine gearboxes) 45860 900 High frequency induction heating, water quenching, 380 320 Tempering 45.

45 steel for gears is not recommended unless it is a low-speed and light-loaded. For high speed or heavy load, you should consider 20CrMnti, or 20CrNimo, 22CrMo and other materials! When low-speed and heavy-duty transmission, the soft tooth surface gear transmission is generally used, the so-called soft tooth surface is the gear that has not been heat treated after processing, the tooth surface width is generally 6-15 times of the modulus, and the helix angle is 10-20 °

Normalizing 150 180hbs

Quenched and tempered 210 285hbs

Case quenching 43 48HBS

Gear working conditions: The hardness of the heat treatment process of the steel grade requires working under low load, and requires high wear resistance of the gear 15 (20) 900 950 carburizing, direct quenching or 780 800 water quenching, 180 200 tempering.

58 63hrc low speed (<, unimportant transmission gears and hanger frame gears that work at low loads 45840 860 normalizing 156 217hrc low speed (<, gears working at low loads (such as gears on lathe slides) 45820 840 water quenching.

500 550 Tempering 200 250HRC Working at medium, medium or heavy loads (secondary gears in lathe gearboxes) 45860 900 High frequency induction heating, water quenching, 350 370 Tempering 40 45 HRC gears operating at large or medium loads, with high tooth requirements (secondary gears in drilling machine gearboxes) 45860 900 High frequency induction heating, water quenching, 380 320 Tempering 45.

Blanking - forging (changing the direction of metal fibers) - normalizing (eliminating the internal stress of forging) - rough turning (making the surface of the workpiece achieve uniform hardness) - quenching and tempering (making the workpiece obtain comprehensive mechanical properties) - finishing - internal hole insert, external tooth making - high-frequency quenching of the tooth surface (making the tooth surface achieve high hardness and high wear resistance) - grinding or shaving (making the tooth surface achieve good roughness, good hub accuracy).

You can use the library to know, there is there.

The surface is carburized and quenched.

840 860 Quenched, water-cooled. Low temperature tempering 180, hardness HRC55; High temperature tempering 500, hardness HRC25 30.

1.First of all, the questions you ask are okay.

2.When the requirements are higher, the gear is generally forged, because the metallographic structure of the gear develops along the longitudinal direction after forging, that is to say, its structure will bend outward at the tooth shape, so the tooth surface strength and toughness are better.

3.For general occasions, gears can be processed with 40cr round steel slices and then heat treated, because that's what our factory does.

4. 40cr can be used in general occasions, and 20crmnti5 is commonly used in high-demand occasionsIf you use 40cr to process and generally use high-frequency quenching, the depth of the hardened layer should be determined according to the size of the modulus.

6.Some of the less demanding, large gears can be made of cast materials.

The blank manufacturing method of the gear can be forged or cast.

So probability-wise, the question you're asking is possible.

However, if the force is relatively large and the working intensity is large, the forged blank is generally used.

Forging is like kneading, which will produce a certain internal streamlined structure of the material, which is parallel and basically parallel to the surface of the workpiece within a certain thickness, so that the internal structure is much stronger than the cast structure, and the more it is subjected to heavy loads, the more obvious the advantage.

Therefore, depending on what your gear is used for, if it is a drive gear of a heavy-duty machinery, it is best to process it directly without round bars.

If it's just a gear for light loads, it's perfectly fine.

The key depends on the requirements of the gear, if the relevant parameters are required to be high (flaw detection, grain size, edge segregation, etc.), it is not possible!!

If the requirements are not high, it is completely possible, and there is a gear factory that purchases forging circles from my house and goes back to process them directly into gears.

Absolutely! That's what we do, do high-frequency quenching!

It can be directly processed with 40cr round steel and reheattreated.

It depends on what kind of heat treatment it has. Aspect ratio of round material. 40cr general heat treatment deformation is small.

It depends on what occasion it is used for.

20Cr2Ni4 is generally normalized, and if the surface hardness is high, the surface carburizing is carried out.

20Cr2Ni4 steel is a high-strength alloy carburizing steel, and the executive standard: GB T 3077-2015

20Cr2Ni4 has good comprehensive mechanical properties, and its hardenability and toughness exceed that of 12CrNi3 steel. The forging performance of the steel is good, the forging heating temperature is 1200, the first forging temperature is 1150, the final forging temperature is greater than 850, and the draft cherry blossom is slowly cooled after forging. If the grain of 20Cr2Ni4 steel is coarse after forging, even if it is heated by forehand early fire and subsequent carburizing, it will still obtain a coarse Ma's Bijing sparrow structure after quenching.

The chemical composition of 20Cr2Ni4 is shown in the following figure: