M3 Type 2 High Speed Steel

M3 Type 2 High Speed Steel (M3-2) is a high speed steel with an outstanding balance of red hardness, edge toughness and wear resistance. The additional carbon and vanadium provide superior resistance to abrasion and edge breakdown, which makes M3 Type 2 a superb tool material for form tools and roll turning. Increased tool life will also be experienced in the machining of heat-treated sections, castings and similar hard materials.

APPLICATIONS: Form tools, spade drills, milling cutters and broaches.

Composition

Relative Properties

Physical Properties

• Density: 0.295 lb/in³ (8166 kg/m³)
• Specific Gravity: 8.17
• Modulus of Elasticity: 30 x 10⁶ psi (207GPa)
• Machinability: 35-40% of a 1% carbon steel

Heat Treating Instructions

Hardening

Critical Temperatures: Ac1: 1535°F (835°C)

Preheating: To minimize distortion and stresses in large or complex tools use a double preheat. Heat at a rate not exceeding 400°F per hour (222°C per hour) to 1100°F (593°C) equalize, then heat to 1450-1550°F (788-843°C). For normal tools, use only the second temperature range as a single preheating treatment.

Austenitizing (High Heat): Heat rapidly from the preheat.
Furnace: 2200-2250°F (1204-1232°C)
Salt: 2175-2225°F (1191-1218°C)

Quenching: Pressurized gas, warm oil, or salt. For pressurized gas, a rapid quench rate to below 1000°F (538°C) is critical to obtain the desired properties. For oil, quench until black, about 900°F (482°C), then cool in still air to 150 -125°F (66-51°C). For salt maintained at 1000-1100°F (538-593°C), equalize, then cool in still air to 150 -125°F (66-51°C). For large tools: remove from the salt quench when the tool reaches approximately 1500°F (816°C), quench in oil until black, about 900°F (482°C), then air cool to 150 -125°F (66-51°C).

Tempering: Temper immediately after quenching. Typical tempering range is 1020-1050°F (549-566°C). Hold at temperature for 2 hours, then air cool to ambient temperature. Double tempering is required, triple tempering is recommended.

Annealing

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 1550-1575°F (843-857°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. The resultant hardness should be 255 HBW or lower.