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![](../../indexgifs/cructabswhthome.gif) |
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CPM® REX® M4HC(HS)*
(AISI M4) |
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![](../prodbyappnavgifs/CrucDataHeader.gif) |
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CPM REX M4HC(HS) is a 4% vanadium high speed steel with good heat resistance and wear resistance between that of AISI D2 and CPM 10V/CPM 9V. For application hardnesses of HRC 60 or above, CPM M4 offers the best combination of strength, wear and toughness. Its machinability and grindability are excellent compared to D2 or the higher vanadium CPM materials.
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Typical Chemistry |
Carbon |
1.40% |
Manganese |
0.30% (0.70%)* |
Silicon |
0.55% |
Chromium |
4.00% |
Vanadium |
4.00% |
Tungsten |
5.50% |
Molybdenum |
5.25% |
Sulfur |
0.06% (0.22%)* |
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Typical Applications |
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Screws |
Tips |
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Gate/Runner Inserts |
Mold Inserts |
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Pelletizer/Granulator Blades |
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*The addition of .20/.25 S in larger diameter rounds (e.g. 2-9/16" and over) provides a uniform dispersion of small sulfides throughout the structure, resulting in machinability and grindability benefits with no deleterious effect on toughness. |
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- Annealed Hardness: BHN 225/255
Machinability in the annealed condition is approximately 45% of W1 Tool Steel (1%C), with about 30% additional improvement with the high sulfur modification.
Thermal Treatments
Critical Temperature: 1545F (840C)
Forging: 2000-2100F(1095-1150C). Do not forge below 1700F (930C). Slow cool.
Annealing: 1600F (870C), hold 2 hours, slow cool 30F (15C)/hr max. to 1000F (540C), then air or furnace cool. Hardness BHN225/255.
Stress Relieving (After machining): 1100-1300F(595-740C), hold 2hrs. and air or furnace cool.
Straightening: Best done warm 400-800F(200-430C.)
Hardening: (Salt, vacuum or atmosphere)
Preheat: 1500-1550F(820-845C), equalize. Second preheat stage at1850-1900F(1010-1040C) suggested for high temperature hardening in vacuum.
High Heat: 1875-2200F(1025-1205C). 2150-2200F(1175-1205C) recommended for cutting tools. 1875-2125F(1025-1160C) recommended for cold work applications.
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Quench: Salt, oil or atmosphere quench to 1000-1100F(540-595C), equalize, then air cool to below 150F(66C) or hand warm. Vacuum or atmosphere quench rate through 1850-1300F(1010-705C) range is critical to achieve optimum heat treat response.
Temper: 1000F(540C) minimum recommended. Double tempering required and triple tempering recommended when hardening from 2100F(1150C) or higher. Air cool to room temperature between tempers.
Stress-relieving (Hardened parts): Temper 30F(15C) below original tempering temperature.
Toughness
C-Notch Charpy impact and Bend Fracture strengths related to hardening and tempering temperatures follow:
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Hardening
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Tempering
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Hardness
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Charpy C-Notch
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Bend Fracture
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Temperature
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Temperature
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Impact Value
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Strength
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°F
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°C
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°F
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°C
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HRC
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ft-lb
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(Joules)
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(ksi)
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(MPa)
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2200
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1205
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1025
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550
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65.5
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20
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27
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738
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5088
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2125
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1165
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1050
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565
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63.5
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28
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38
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744
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5129
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Hardening Data
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Tempering
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HEAT TREAT RESPONSE ±1 HRC (NOTE A)
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Temperature
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1875F
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1975F
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2050F
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2100F
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2150F
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2200F
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°C
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°F
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(1025C)
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(1080C)
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(1120C)
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(1150C)
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(1175C)
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(1205C)
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As Quenced
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59.5
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62.5
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64.5
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65
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65
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63.5
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540
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1000
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58.5
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61
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62.5
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63.5
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65
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66
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OPTIMUM FOR MAXIMUM TOUGHNESS AND EFFECTIVE STRESS-RELIEVING.
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550
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1025
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58
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60.5
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62
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63
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64.5
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65.5
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565
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1050
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57.5
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59.5
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61
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62
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63.5
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64.5
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595
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1100
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54
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56
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58.5
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60
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61.5
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62.5
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620
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1150
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50
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53
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55
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56
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58
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59
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650
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1200
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44
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48
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51
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52
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54
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55
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NOTE A:
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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)
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45
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30
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20
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15
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10
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5
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MINIMUM NUMBER
OF TEMPERS (2 HRS)
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2
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2
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2
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3
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3
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3
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Size Change During Hardening |
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- Hardening
- Temp.
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- Tempering
- Temp.
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HRC
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- Longitudinal
- Size Change
%
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°F
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°C
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°F
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°C
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2200
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1205
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1025
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550
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65.5
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+.15
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![](../../indexgifs/chemheatslug.gif) |
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Surface Treatments
CPM REX M4HC(HS) 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 ...................................................................31 psi x 106 (214 GPa)
Specific gravity ............................................................................................................7.97
Density .......................................................................................0.288 lb/in3 (7972 kg/m3)
Coefficient of Thermal Expansion
- Temperature
- Range
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- Coefficient of Thermal
- Expansion
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°F
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°C
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in/in/°Fx10-6
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mm/mm/°Cx10-6
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100- 500
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40-260
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6.40
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11.5
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100- 800
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40-425
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6.58
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11.8
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100-1100
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40-540
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6.72
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12.1
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