y
REX® M3-1
(AISI M3-1)
REX M3-1 is a lower carbon, lower vanadium modification of M3-2 high speed steel. This lower alloy content results in better machining and grinding characteristics compared to M3-2, with a slight improvement in toughness and a moderate decrease in wear resistance in between that of M2 and M3-2.
Typical Chemistry
Carbon 1.02%
Manganese 0.25%
Silicon 0.30%
Chromium 4.00%
Vanadium 2.40%
Tungsten 5.75%
Molybdenum 5.00%
Sulfur 0.03% Max.
Typical Applications
Broaches Milling Cutters
Form Tools Spade Drills
Annealed Hardness: BHN 225/255.

Machinability in the annealed condition is approximately 30% of W1 Tool Steel (1%C).

Thermal Treatments

Critical Temperature: 1535F(835C)

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 225/255

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

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

Hardening: (Salt Bath, Vacuum or Atmosphere)

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

High Heat: 2150-2225F(1175-1220C), soak 2 to 5 minutes. Typical maximum temperature recommended for salt bath hardening is 2200-2210F(1205-1210C).

Quench: Salt or oil to 1000-1100F(540-595C), equalize, then air cool to hand warm, 125F(50C). Temper immediately. The vacuum quench rate to below 1000F(540C) is critical to achieve comparable results.

Temper: Tempering at 1000F(540C) or higher 3 times for at least 2 hours at temperature is recommended. Air cool to room temperature between tempers.
Hardening Data
Tempering
HEAT TREAT RESPONSE ±1 HRC (NOTE A)
Temperature
2100F
2150F
2200F
2225F
°C
°F
(1150C)
(1175C)
(1205C)
(1218C)
As Quenced
65
65
64
63
540
1000
63.5
65
66
66.5
OPTIMUM FOR MAXIMUM TOUGHNESS AND EFFECTIVE STRESS-RELIEVING.
550
1025
63
64.5
65.5
66
565
1050
62
63.5
64.5
65
595
1100
60
61.5
62.5
63
620
1150
56
58
59
61
650
1200
52
54
55
57
NOTE A:
RESULTS MAY VARY WITH HARDENING METHOD AND SECTION SIZE. SALT OR OIL QUENCHING WILL GIVE MAXIMUM RESPONSE. VACUUM OR ATMOSPHERE COOLING MAY RESULT IN UP TO 1-2 HRC POINTS LOWER.
MINIMUM TIME AT
AUST TEMP (MINS)
10
5
3
2
MINIMUM NUMBER
OF TEMPERS (2 HRS)
3
3
3
3
Size Change During Hardening
Hardening
Temp.
Tempering
Temp.
HRC
Longitudinal
Size Change
%
°F
°C
°F
°C
2200
1205
1025
550
65.5
+.23
Surface Treatments
REX M3-1 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 ............................................................................................................8.16
Density .......................................................................................0.295 lb/in3 (8159 kg/m3)
Coefficient of Thermal Expansion
Temperature
Range
Coefficient of Thermal
Expansion
°F
°C
in/in/°Fx10-6
mm/mm/°Cx10-6
70-500
21-260
6.4
11.5
70-800
21-425
6.6
11.8
70-1000
21-540
6.7
12.1
Toughness
Optimum toughness is achieved by tempering in the range 1025-1050F(550-565C), and selecting the lowest hardening temperature necessary to attain the desired hardness after tempering. The use of lower hardening temperatures (underhardening) helps maintain finer grain size thereby improving toughness.
Return to top of page