CRUCIBLE 416R
CRUCIBLE 416R is a hardenable chromium stainless steel particularly suited for use in high quality precision rifle barrels. This grade has good machinability and, because of closely controlled chemistry and processing techniques, may be machined and lapped to a high finish, which is important for bore accuracy. CRUCIBLE 416R may be purchased either annealed or heat treated to a hardness of about 270 Brinell.
Typical Chemistry
Carbon 0.12%
Chromium 12.50%
Manganese 0.40%
Phosphorus 0.03%
Sulfur 0.13%
Silicon 0.40%
Molybdenum 0.40%
Forging
CRUCIBLE 416R should be forged at 2050 to 2150°F (1121 to 1177°C) and finished above 1400°F (760°C). CRUCIBLE 416R is not adaptable to severe upset forging operations.

Annealing
CRUCIBLE 416R should be annealed for maximum softness at 1550°F (843°C), followed by a furnace cool. For better machinability, a semi-anneal at 1300°F (704°C) is recommended.

Hardening and tempering
CRUCIBLE 416R can be hardened by air cooling or oil quenching from 1750 to 1850°F (954 to 1010°C). When air hardening small or thin sections, a temperature in the upper part of this range should be used. Tempering should be at the proper temperature to give the desired properties as shown below.
Note: Specific applications should not be undertaken without independent study and evaluation for suitability.

Attainable hardness
Attainable hardness is defined as the hardness obtained on cooling a sample approximately 1/2" in thickness in air from 1825°F (996°C). This hardness gives some idea of the mechanical properties of the material which might be expected after hardening and tempering. The attainable hardness of CRUCIBLE 416R is guaranteed to RC35 minimum.

Forming
CRUCIBLE 416R will withstand only gradual cold working. It is not adaptable to severe cold-forming operations.

Welding
CRUCIBLE 416R is not generally recommended for welding as porosity results where sulfur (or selenium) is introduced.

Resistance to scaling
CRUCIBLE 416R scales at approximately 1250°F (677°C). This temperature can vary with the type of atmosphere and application.
Note: Temperatures shown throughout this data sheet are metal temperatures.

General corrosion resistance
The corrosion resistance of CRUCIBLE 416R was evaluated in a variety of corrosion tests normally used for this type of stainless. The corrosion resistance of CRUCIBLE 416R is comparable to that of AISI Type 416. Typical data are given below.
Surface area showing corrosion
(in percent)
Grade
Water Vapor
Column
(24 Hours)
 100%
Relative
Humidity
(200 Hours)
CGA		 5%
Salt
Spray
(2 Hours)
CGA
CGA
 Hardened &
Tempered
U P U P U P U P
Type 416R
 20 1 13 10 6 4 19 13
CGA — Centerless-Ground-Annealed U — Unpassivated P— Passivated
Passivatlon
It is recommended that finished parts machined from stainless steel be passivated for optimum corrosion resistance.
    Free-machining types are prone to dulling and discoloration in passivating treatments. It is important that correct procedures be followed when passivation is specified. The recommended treatment for CRUCIBLE 416R is shown below:
Acid
concentration
by volume of
concentrated
nitric acid
 Sodium
dichromate
by weight		 Bath
temperature		 Immersion
time
(min.)
°F
 °C
40-60% 2.0% 110-140
(120Typ.)		 43-60
(49 Typ.)		 15-30
Machining
The machining of all high-chromium steels is characterized by the tendency of the chip to gall or build up on the cutting edges and radii of the tool. CRUCIBLE 416R gives freer cutting properties and minimizes the tendency of the steel to form a built-up edge on the tool. The chips are short and brittle which results in relatively easy chip control. For the majority of applications material which has been heat treated to about 200 Brinell or annealed and cold drawn is preferred to materials in the annealed condition. The additional hardness obtained by either heat treating or cold drawing reduced the tendency of the chip to build up on the cutting edge, thus allowing a better machine finish.
Machining data
Operation
 Tool Width or
Depth of Cut
 CRUCIBLE 416
High Speed Tooling
 Carbide Tooling
Speed
(fpm)
 Feed
(in/rev)
 Speed
(fpm)
 Feed
(in/rev)
Turning single point
 0.050
0.250
0.500
 160
150
140
 0.0060
0.0055
0.0045
 280
220
210
 0.015
0.030
0.045
Forming
 1/2 wide
1 wide
1 1/2 wide
2 wide
 155
150
150
140
 0.0020
0.0017
0.0015
0.0013
 240
240
225
200
 0.003
0.002
0.002
0.002
Cuttoff
 1/16 wide
1/8 wide
3/16 wide
1/4 wide
 150
150
155
160
 0.0017
0.0020
0.0020
0.0025
 240
240
225
200
 0.003
0.002
0.002
0.002
Drilling
 1/16 dia.
1/8 dia.
1/4 dia.
1/2 dia.
3/4 dia.
1 dia.
 95
100
100
100
105
105
 0.0020
0.0030
0.0040
0.0045
0.0050
0.0065
Threading †
 15-40
 –
Tapping †
 15-25 dia.
 –
† Use the higher speeds for the finer threads.
Physical properties
Modulus of elasticity in tension...........................psi. 29,000,000 (MPa 199,810)
Modulus of elasticity in torsion.............................psi.10,500,000 ( M Pa 72,345)
Room temperature Electrical resistivity
(microhm—centimeters).....................................................................................56.8
Specific heat (Btu/lb./°F)...........................................32-212°F.................(0-100°C)
Specific gravity..................................................................0.11...............................7.75
Weight (Ib./cu.in.)...........................................................0.280................(7.75 g/cm3)
Thermal conductivity (Btu/hr./sq. ft./°F/ft.)
                             200°F......................................................................................(93°C)
                          1000°F....................................................................................(538°C)
Mean coefficient of thermal expansion (in/in/°F x 10)
                          32-212°F (0-100°C) .....................................................................5.5
                          32-600°F (0-316°C) .....................................................................5.6
                          32-1000°F (0-538°C) ...................................................................6.4
                          32-1200°F (0-649°C) ...................................................................6.5
Melting point range
                          (°F) ....................................................................................2700/2790
                          (°C) ...................................................................................1482/1532

Mechanical properties
(All values are representative properties in the annealed condition)
                                                                                                                    Bar (1 in. rd.)
Tensile strength.................................................................psi.75,000 (516.75 MPa)
Yield strength (0.2% offset).......................................................40,000 (275.6 MPa)
Elongation in 2 in. (%)...............................................................................................30
Reduction of area (%) ..............................................................................................60
Hardness (BHN) .....................................................................................................155
Short time elevated temperature tensile strength:
Temperature
 Tensile Strength
°F
 °C
 psi
1000
 538
 45,000
1100
 593
 33,000
1200
 649
 22,000
1300
 704
 14,000
1400
 760
 9,000
Room temperature mechanical properties as heat treated

Typical Values: Size 1" rd. Tensile 0.505 in. diam.
All martensitic stainless steels have reduced ductility at very low temperatures. For this reason, caution should be exercised in the design of barrels for use at extremely low temperatures.
Creep Data
Temperature Stress for creep rate
of 0.0001% per hour
psi
°F °C
1000 538 9,200
1100 593 4,200
1200 649 2,000
1300 704 1,000
Note: Properties shown throughout this data sheet are typical values. Normal variations in chemistry, size and conditions of heat treatment may cause deviations from these values. For additional data and metallurgical engineering assistance consult your local Crucible Service Center.
Return to top of page