M7 high-speed steel is used for making heavier construction drills where flexibility and extended drill life are extremely important. M7 molybdenum high-speed tool steels are mainly used for cutting tools in all machining operations. This steel exhibits good abrasion-resistance because of its carbon and vanadium contents. It is an excellent choice for premium tools which require an outstanding balance of red hardness, edge toughness and wear-resistance. It is especially suited for machining semi-hard, heat-treated steel at about 300-350 Brinell Hardness.
Other Known Names: 1.3348, HS 2-9-2, E M7, REX M7®, SKH 57, Tatmo-VN.
Griggs Steel Color Code:Gold
Drills, End Mills, Pins, and Reamers.
Density
0.287 lb/in3 (7944 kg/m3)
Specific Gravity
7.94
Modulus Of Elasticity
30 x 106 psi (207 GPa)
Machinability
45-50% of a 1% carbon steel
| Maximum | Typical | ||||||
|---|---|---|---|---|---|---|---|
| Carbon | Chromium | Tungsten | Molybdenum | Vanadium | Cobalt | Annealed | Tempered |
| C | Cr | W | Mo | V | Co | Hb | HrC |
| 1.02 | 3.8 | 1.8 | 8.6 | 1.9 | - | 260 | 64 |
| Annealing | Preheat | Austenitizing | Quench | Tempering |
|---|---|---|---|---|
| Temp | Temp | Temp | Medium | Temp |
| °F | °F | °F | °F | |
| 1575/1650 | 1500/1550 | 2125/2175 | Salt/Oil/Atm | 1025/1050 |
Heat rapidly from the preheat.
Soak 2 -5 minutes at temperature.
To maximize toughness, use the lowest temperature.
To maximize hot hardness, use the highest temperature.
Annealing must be performed after hot working and before re-hardening
Heat at a rate not exceeding 400°F per hour (222°C per hour) to 1550-1600°F (843-871°C), and hold at temperature for 1 hour per inch (25.4 mm) of thickness, 2 hours minimum. Then cool slowly with the furnace at a rate not exceeding 50°F per hour (28°C per hour) to 1000°F (538°C). Continue cooling to ambient temperature in the furnace or in air.