Vacuum heat treatment for parts production

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Vacuum heat treatment is an indispensable process in the production and processing of parts.

The position of the vacuum heat treatment process in the processing route is determined according to the purpose and function of the vacuum heat treatment. The purpose of pre-vacuum heat treatment is to eliminate the internal stress of the manufactured blank, refine the grains, homogenize the structure, reduce the original defects, improve the machinability, and prepare the structure for the final vacuum heat treatment. Pre-vacuum heat treatment includes vacuum annealing, vacuum normalizing, and vacuum tempering. Generally after blank production, before cutting or before finishing.

The purpose of the final vacuum heat treatment is to obtain the technical properties required by the drawings, and the final vacuum heat treatment includes vacuum quenching, vacuum tempering and chemical vacuum heat treatment. The hardness of the parts after the final vacuum heat treatment is generally high, and it is only suitable for grinding. Generally, this process is arranged at the back of the process route as much as possible.

In the roughing stage, most of the allowance of each machined surface of the part is removed, in order to improve productivity. The semi-finishing stage is to prepare for the finishing of the main surfaces, to ensure a certain machining accuracy and a certain finishing allowance of these surfaces, and to complete some secondary final machining, which is generally carried out before vacuum heat treatment. In the finishing stage, the finishing of each main surface is completed to ensure that each main surface meets the requirements of the drawings.

The principles of machining process arrangement are as follows:

① Arrange rough machining first, then semi-finishing, and finally finishing.

② Arrange the main surface processing first, and then arrange the secondary surface processing.

③ First the reference surface and then the other surfaces.

Typical parts heat treatment

Example of gear heat treatment:

Working conditions, materials and heat treatment requirements

1.Conditions: low speed, light load and no impact

Requirements: HT200 HT250 HT300 Stress Relief Annealed

2.Conditions: low speed (<1m/s), light load, such as lathe slide gears, etc.

Requirements: 45 tempering, HB200-250

3.Conditions: low speed, medium load, such as standard series reducer gears

Requirements: 4540Cr 40MnB (5042MnVB) quenched and tempered, HB220-250 Y

4.Conditions: low speed, heavy load, no impact, such as machine tool headstock gear

Requirement: 40Cr (42MnVB) quenching and tempering at medium temperature HRC40-45

5.Conditions: medium speed, medium load, no violent impact, such as machine tool spindle box gear

Requirements: 40Cr, 40MnB, 42MnVB quenched and tempered or normalized, induction heating surface quenching, low temperature tempering, aging, HRC50-55

6.Conditions: medium speed, medium load or low speed, heavy load, such as secondary gears in lathe gearboxes

Requirements: 45 high-frequency quenching, 350-370C tempering, HRC40-45 (if there is no high-frequency equipment, rapid heating tooth surface quenching can be used)

7.Conditions: medium speed, heavy load

Requirements: 40Cr, 40MnB (40MnVB, 42CrMo, 40CrMnMo, 40CrMnMVBA) quenched, tempered at medium temperature, HRC45-50.

8.Condition: high speed, light load or high speed, medium load, pinion with impact

Requirements: 15, 20, 20Cr, 20MnVB carburizing, quenching, low temperature tempering, HRC56-62.38CrAl 38CrMoAl nitriding, nitriding depth 0.5mm, HV900

9.Conditions: high speed, medium load, no violent impact, such as machine tool spindle wheel.

Requirements: 40Cr, 40MnB, (4OMnVB) high frequency quenching, HRC50-55.

10.Conditions: high speed, medium load, impact, complex shape and important gears, such as automobile gearbox gears (20CrMnTi has high hardenability, small overheat sensitivity, fast carburizing speed, uniform transition layer, direct quenching after carburizing Small deformation, good machinability after normalizing, good low temperature impact toughness)

Requirements: 20Cr, 20Mn2B, 20MnVB carburizing, quenching, low temperature tempering or high frequency quenching after carburizing, HRC56-62.18CrMnTi, 20CrMnTi (forging → normalizing → machining gear → local plating → carburizing, pre-cooling quenching, low temperature Tempering→grinding→shot peening) carburized layer depth 1.2-1.6mm, gear hardness

HRC58-60, core hardness HRC25-35. Surface: tempered martensite + retained austenite + carbide. Center: sorbite + fine pearlite

11.Conditions: high speed, heavy load, shock, modulus

Requirements: 20Cr, 20Mn2B carburizing, quenching, low temperature tempering, HRG56-62.

Equipment selection: The RVGQ series vacuum heat treatment furnace produced by SIMUWU is a high-quality product for the vacuum heat treatment of tooling and molds. The 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 annealing furnace, vacuum oil quenching furnace, vacuum brazing furnace, etc., which are widely sold in developed and developing countries.