REX TMO®
(AISI M1)
REX TMO molybdenum-tungsten high speed steel is a tough general purpose high speed steel with high cutting efficiency and excellent finishing properties. It is adapted to fast light cuts on soft or medium hard materials.
Typical Chemistry
Carbon 0.83%
Manganese 0.30%
Silicon 0.35%
Chromium 3.75%
Vanadium 1.15%
Tungsten 1.70%
Molybdenum 8.50%
Typical Applications
Chasers Reamers
Drills Taps
End Mills Thread Rolling Dies
Punches Tool Bits
Annealed Hardness: BHN 217/235.

Machinability in the annealed condition is approximately 50% of W1 Tool Steel (1%C).

Thermal Treatments

Critical Temperature: 1520F(827C)

Forging: 2075F(1135C) Do not forge below 1700F(925C). Slow cool after forging.

Annealing: 1600F(870C), hold 2 hours, slow cool 25F(15C)/ hr max. to 1000F(535C), then air or furnace cool. Hardness BHN 217/235

Stress Relieving: 1100-1300F(595-740C), hold 2 hrs. and air or furnace cool.

Straightening: Best done warm 400-800F(205-425C)

Hardening: (Salt Baths or Vacuum Furnace preferred)

Preheat: 1500-1550F(815-845C), equalize

High Heat: 2100-2200F(1150-1205C), soak 2 to 5 minutes. For vacuum hardening, use the high side of the high heat range and soak times.

Quench: Salt or oil to 1000-1100F(540-595C),equalize, then air cool to hand warm, 150F(65C). Temper immediately. The vacuum quench rate to below 1000F(540C) is critical to achieve comparable results.

Temper: Tempering at 1000F(540C) or higher 2 times for at least 2 hours at temperature is recommended. Air cool to room temperature between tempers.
Hardening Data
Oil quenched.
Tempering
Hardness HRC
Temperature
2100F
(1150C)
2150F
(1175C)
2250F
(1230C)
°F
°C
1000
540
64.5
65.6
66
OPTIMUM FOR MAXIMUM TOUGHNESS AND EFFECTIVE STRESS-RELIEVING.
1025
550
64.3
65.5
66
1050
565
63.8
64.9
65.5
1075
580
62.6
63.9
64.8
1100
595
61
62.5
63.5
1125
605
59.5
61
62
1150
620
57
58.7
60.5
Size Change During Hardening
Hardening
Temp.
Tempering
Temp
HRC
Longitudinal
Size Change %
°F
°C
°F
°C
2175
1190
1025
550
65
+.24
Surface Treatments
REX TMO can be nitrided, steam tempered, or titanium-nitride coated if desired. If the CVD TiN treatment is used, care is required in vacuum hardening.

Physical Properties
Modulus of Elasticity ...................................................................30 psi x 106 (207 GPa)
Specific gravity ............................................................................................................7.93
Density .......................................................................................0.286 lb/in3 (7930 kg/m3)
Coefficient of Thermal Expansion
Temperature
Range
Coefficient of Thermal
Expansion
°F
°C
in/in/°Fx10-6
mm/mm/°Cx10-6
100- 500
40-260
5.85
10.5
100- 800
40-425
6.75
12.2
100-1000
40-540
6.93
12.5
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