Introduction to M2 High Speed Steel
Molybdenum high-speed steel tool steel, from the perspective of ensuring red hardness, Mo and W have similar functions. The steel has the advantages of small carbide unevenness and high toughness, but there are two major shortcomings, which limit its application.
First, the tendency of decarburization is relatively high, so the requirements for heat treatment protection are stricter;
The second is that the grains have a greater tendency to grow and are prone to overheating, so the quenching heating temperature should be strictly controlled.
2. Supply status and hardness
Annealed state, hardness 248HBS;
Cold drawn state, hardness 262HBS;
Cold drawn state, annealing hardness 255HBS.
3. Typical chemical composition (mass fraction, %)
C 0.78~0.88
Si 0.20~0.45
Mn 0.15~0.40
P ≤0.030
S ≤0.030
Cr 3.75~4.50
Mo 4.50~5.50
V 1.75~2.20
W 5.50~6.75
4. Refer to the corresponding steel number
United States UNS standard steel grade T11302
American ASTM/AISI/SAE standard steel grade M2 (normal carbon)
5. Thermal processing specifications
The starting temperature is 1040! 1150°C, and the ending temperature is 930°C.
6. Annealing specification
The temperature is 820~870℃, and the hardness after annealing is 207~235HBS.
7. Common quenching and tempering specifications
The quenching temperature is 1190~1230℃, the quenching medium is oil, air cooling or salt bath, the tempering temperature is 540~600℃, and the hardness is 65~60HRC.
8. Mold quenching and tempering specifications
The preheating temperature is 730~850℃, the quenching temperature is 1216℃ in the salt bath furnace, the controllable atmosphere furnace is 1227℃, the tempering temperature is 550℃, and the hardness after tempering is ≥64HRC.
9. Examples of typical applications
a. Suitable for molds that bear vibration and impact load: deep drawing molds, punching molds.
b. Metal cutting saw blades, cold heading and extrusion tools, etc.