Application of vacuum quenching furnace in M2 high-speed steel

2025-11-06 13:57

M2 high-speed steel is a widely used general-purpose high-speed tool steel, belonging to the molybdenum-type high-speed steel family.

High Hardness: After heat treatment, it can achieve a very high hardness.

High Wear Resistance: Containing high levels of alloying elements such as carbon, molybdenum, tungsten, and vanadium, it possesses excellent wear resistance.

Excellent Red Hardness: This is one of the most important characteristics of high-speed steel. “Red hardness” refers to the ability to maintain high hardness and cutting performance even when subjected to high temperaturesduring high-speed cutting. M2 excels in this aspect.

The following is the process flow for vacuum quenching and vacuum tempering required to obtain M2 high-speed steel:

1.Preheating Stage

First Preheating: Temperature controlled between 550°C and 650°C, holding time approximately 10 to 20 minutes after furnace through-heating.

Second Preheating: Temperature raised to between 850°C and 900°C, holding time approximately 10 to 20 minutes after furnace through-heating.

2.Austenitizing and Gas Quenching

Quenching Heating: The temperature is rapidly raised to the austenitizing temperature, ranging from 1180°C to 1230°C. Holding time is determined based on workpiece size, typically 2 to 10 minutes.

High-Pressure Gas Quenching: High-purity nitrogen or helium is used as the cooling medium, with pressure typically between 0.5 MPa and 1.0 MPa or higher. Cooling must continue until the workpiece temperature drops below 50°C to ensure complete martensite transformation.

3.Multiple Tempering Stages

To eliminate brittleness, transform retained austenite, and achieve secondary hardening, multiple high-temperature tempering stages are necessary:

Tempering Temperature: The optimal temperature range is 540°C to 570°C.

Holding Time: Each tempering stage requires holding at that temperature for 1 hour or longer to ensure complete heat penetration.

Number of Tempering Stages: M2 high-speed steel requires at least 2 tempering stages, typically.

Cooling Requirements: Crucially, the workpiece must be completely cooled to room temperature after each tempering stage. This is essential for ensuring retained austenite transformation and achieving the final high hardness.

The following are the specific parameters of the vacuum quenching furnace required for vacuum quenching and tempering of high-speed steel M2:

Furnace type	Horizontal type,single chamber, internal recycle
Loading method	Front Loading
Max. Loading size	500×500×700(W×H×L mm)
Max. Loading weight	400kg (including jig)
Power supply	3 phase, 380V(±5%); 50Hz
Total power	170kw
Heating power	140kw
Cooling fan motor power	132kw
Max.design temperature	1300℃
Working temperature	1250℃
Temperature uniformity	9 points temp testing (±5℃) (standard AMS 2750F)
Temperature control accuracy	S Type thermocouple ≤ ±1℃
Quantity of heating zones	1 zone
Heating element	High-purity graphite
Heating rate(The room temperature of the empty furnace rises to 1100℃)	0～20℃/min（Adjustable）
Ultimate vacuum(Empty furnace, cold state, after drying and degassing)	7×10^-3pa
Working vacuum（Empty furnace，room temperature）	5×10^-2pa
Time to reach working vacuum(Empty furnace, cold state, clean condition; from atmospheric pressure to working vacuum)	≤70min(including diffusion pump heating time)
Pressure rise rate (empty furnace, cold state)	≤0.67Pa/h
Cooling method	Air cooling/natural cooling
Cooling air	Nitrogen or Argon (purity: 99.99% or 99.999%)
Cooling rate (empty furnace, 1100°C~200°C)	≤ 40-300℃/min
Max charging pressure(absolute pressure and adjustable)	＜6 bar
Temperature control mode	Intelligent programmable temperature controller for automatic temperature control
Control mode	PLC automatic / manual control interlock protection
Equipment color	Customized