CRUCIBLE HOLDER BLOCK
(AISI 4150 Modified)
Crucible Holder Block is a prehardened (26/30 HRC) free machining medium alloy steel intended for holders or backers for plastic molds, die casting dies, and cold or hot forming tools. It may also be used for light cold forming tools such as brake dies.
Typical Chemistry
Carbon 0.50%
Manganese 1.25%
Silicon 0.25%
Chromium 0.65%
Molybdenum 0.18%
Sulfur 0.08%
Typical Applications
Brake Dies Plastic Mold Frames
Backers Prototype Molds
Die Holders
Hardening

Crucible Holder Block is usually supplied in the prehardened condition, at about 26/30 HRC. Further heat treatment is generally not required.

Preheat: 1250/1350F, equalize.

High Heat: 1525/1575F, hold 30/45 minutes at temperature.

Quench: Oil quench to 350F, then air cool to 200F.

Temper: 400-1200F, hold 2 hours per inch of thickness, air cool to room temperature.
Typical Properties
1" Round, oil quenched from 1525F and tempered as indicated.
Tempering
Temperature °F		 Hardness
HRC
400 56
600 53
800 45
1000 36
1200 30
Toughness
Tempering
Temperature °F		 Izod Impact
ft.- lbs
950 30
1100 50
1200 55
1300 70

Effect of Size
Larger sections will develop slightly lower hardness than smaller sections, due to slower cooling rates during quenching (mass effect). This effect is shown below:
Oil quenched from 1525F, tempered as shown.
Tempering
Temperature °F		 Hardness HRC
1"Rd. 3"Rd. 5"Rd.
900 42 36 35
1000 36 35 33
1100 32 30 29
1200 30 27 25
Surface Treatment
In the prehardened (26/30 HRC) condition, holder block may be nitrided by most conventional nitriding processes. Surface hardness will be about 60/65 HRC. Other coatings or treatments utilizing temperatures of about 1050F or lower may also be used.

Flame/Induction Hardening
Holder Block may be selectively hardened by either flame or induction hardening.

Heat: 1450/1550F.

Quench: In water or oil to approximately 600F.

Cool: To 150/200F

Temper: After hardening is recommended.

Hardness: for typical treatments is shown below:
Flame Hardened, Tempered as indicated.
Tempering
Temperature °F		 Hardness
HRC
AQ 60
400 55
500 54
600 52
700 49
800 47
900 42
Annealing
Holder Block is usually supplied prehardened, and further heat treatment is generally not required.
A. Heat to 1550/1650, hold two hours, cool slowly (50F/hour maximum) to 1200F, then air cool.
Or
B. Heat to 1550/1650, hold two hours, cool to 1200/1250F, hold 4 hours, then air cool.
Typical annealed hardness: 187/229 BHN.

Stress Relieving
Heat to temperature shown below, hold two hours, cool in still air.

Prehardened Material: 1050/1100F.

Annealed Material: 1200/1250F.

Hardened Material: 25/50F below tempering temperature.

Welding
Use 4140 or 4150 filler material.

Prehardened Material: Preheat 600/800F. Maintain above 600F during welding. Temper 1000/1100F.

Annealed Material: Preheat 600/800F. Maintain above 600F during welding. Reanneal, or temper 1200/1250F 4 hours.

Hardened Material: Preheat 25/50 below tempering temperature (400F minimum). Maintain above 400F during welding. Temper 25/50F below tempering temperature.

Physical Properties
Modulus of Elasticity ............................................................29 psi X 106
Density .....................................................................................0.282 lb./in3
Thermal Conductivity ..............................200F............. 23 BTU/hr./ft./°F
Thermal Expansion
      RT-200F ................................................................6.5 X 10-6 in./in./°F
      RT-400F .................................................................7.0 X 10-6 in./in./°F
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