M50 High Speed Steel

M50 High Speed Steel is classified as an intermediate type high speed steel of the molybdenum-chromium-vanadium variety. It is recommended for applications with moderate cutting conditions, such as woodworking tools, where toughness is of prime importance and where there is less need for red hardness.

Composition
  • C
  • Mn
  • Si
  • Cr
  • Mo
  • V
  • 0.84
  • 0.30
  • 0.50
  • 4.10
  • 4.25
  • 1.00
Relative Properties
chart table
Physical Properties
  • Density: 0.283 lb/in3 (7836 kg/m3)
  • Specific Gravity: 7.84
  • Modulus of Elasticity: 29.5 x 106 psi (204GPa)
  • Machinability: 65-75% of a 1% carbon steel
charts
Heat Treating Instructions
Hardening
Critical Temperature:
Ac1: 1490°F (810°C) Ac3: 1555°F (846°C)
Ar1: 1345°F (730°C) Ar3: 1385°F (751°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 1500-1600°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: 2025-2050°F (1107-1121°C)
Salt: 2000-2025°F (1093-1107°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).

Tempering: Temper immediately after quenching. Typical tempering range is 975-1025°F (523-552°C). Hold at temperature for 2 hours, then air cool to ambient temperature. Double tempering is required.

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 1525-1550°F (829-843°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 229 HBW or lower.