Gear Process Vacuum Heat Treatment Furnace

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Vacuum heat treatment of parts with different surface and core requirements (hard outer and inner tough):
Medium carbon steel: quenching and tempering → surface quenching → low temperature tempering (surface 50~55HRC, core 265~280HBS);
Low carbon steel: carburizing → quenching → low temperature tempering (surface 56~62HRC, core 156~179HBS);
38CrMoAl: quenching and tempering → nitriding (surface>700HV, core 26~33HRC, high precision)

Gear vacuum heat treatment:
Gear working conditions – important parts used to transmit power, change direction or speed, and are subject to complex forces.
Common failure forms – gear contact surface wear or tooth surface plastic deformation (insufficient surface hardness); gear surface spalling (fatigue damage, pitting corrosion);
Broken teeth (low toughness or strength or overload).
Technical requirements of gears – high hardness of tooth surface, contact fatigue, wear resistance; gear root and gear have high strength and toughness.
Steel for gears – low and medium carbon steel.
Light Duty Gear: 45, Tempered or Normalized
Medium load gear: 45, 40Cr, quenched and tempered, surface quenching of wear-resistant parts
Heavy-duty gear: 20Cr, 20CrMnTi, carburizing and quenching
High precision gear: 38CrMoAlA, modulated carburizing

Gear vacuum heat treatment process
1. Carburizing gear: Material: 20CrMnTi, 20Cr, 30CrMnTiA, etc. Service occasions: high speed heavy load ((automobile gear)
1) Normalizing: The purpose is to refine the grains; adjust the hardness to facilitate cutting, heat to Ac3 + 30 ~ 50 ° C, air cooling, and obtain fine pearlite + (a small amount of ferrite).
2) Vacuum carburizing: increase the carbon content on the surface, keep at 920~930℃ for 3~9h.
3)Vacuum quenching after vacuum carburizing: obtain martensite, improve surface hardness, direct quenching or one-time quenching.
4) Vacuum tempering: eliminate quenching stress, low temperature 200 ℃

The carburized gear should meet the following requirements after vacuum heat treatment:
1) The hardness of the surface layer is HRC58~63, and the core HRC31~45
2) The surface and core should have a fine-grained structure
3) The metallographic structure of the surface should be fine needle-like or cryptocrystalline martensite structure, with reticulated carbides allowed along the grain boundaries, only a small amount of granular carbides and retained austenite are allowed
4) There should be enough transition layer between the surface and the core
5) Heart tissue after vacuum heat treatment:
Alloy steel, low carbon martensite or low carbon martensite + ferrite;
Carbon steel, pearlite + ferrite
6) Decarburization and deformation are minimized
7) In addition to high toughness, the core must also have high strength.

Heat treatment process curve of gears made of 20 CrMnT steel:

Equipment selection: The RVC series vacuum heat treatment furnace produced by SIMUWU is a high-quality product for the vacuum heat treatment process of tooling and molds. Good temperature control accuracy and temperature control uniformity ensure the effective progress of the vacuum heat treatment process. SIMUWU specializes in the manufacture of vacuum furnaces, has more than ten years of relevant experience, and has a good reputation in the field of vacuum furnace manufacturing. The product line includes vacuum air quenching furnace, vacuum oil quenching furnace, vacuum brazing furnace, etc., which are widely sold in developed and developing countries.