Custom 455® Technical Data
®Custom 455 is a registered trademark of Carpenter Technology Corporation


Type Analysis | Description | Selection | Corrosion Resistance | Elevated Temperature Use
Physical Properties | Heat Treatment | Workability | Typical Mechanical Properties

Type Analysis

Element

Min

Max

Carbon

--

0.05

Manganese

--

2.00

Silicon

--

0.50

Phosphorus

--

0.040

Sulfur

--

0.030

Chromium

11.00

12.50

Nickel

7.50

9.50

Molybdenum

--

0.50

Copper

1.50

2.50

Columbium+Tantalum

0.10

0.50

Description

Recognizing the need for high-strength alloys with good corrosion resistance to atmospheric environments, and a martensitic age-hardenable stainless steel. This alloy is relatively soft and formable in the annealed condition. Asingle-step aging treatment develops exception-alloy high yield strength with good ductility and toughness.
This stainless can be machined in the annealed condition , and welded in much the same manner as other precipitation hardenable stainless steels. Because of its low work-hardening rate, it can be extensively cold formed. The dimensional change during hardening is only about -0.001 in/in, which permits close-tolerance finish machining in the annealed state.
Custom 455 stainless represents a significant advancement in the area of precipitation hardening stainless steels. It should be considered where simplicity of heat treatment, ease of fabrication, high strength and corrosion resistance are required in combination.


Selection

Because of the unique combination of high strength and corrosion resistance of Custom 455 stainless there are few other alloys available for consideration. PH13-8 Mo* can be considered where good transverse toughness and ductility are necessary in large sections. *PH13-8 Mo is registered trademark of ARMCO, Inc.


Corrosion Resistance

Custome 455 stainless resists staining in normal air atmospheres, and shows no corrosion in fresh water. Test in 5% salt spray at 95 °F(35 °C) and in 5% ferric chloride at room temperature have demonstrated good resistance to pitting and rusting. Laboratory test s in a variety of mild chemical environments have shown that the level of general corrosion resistance is superior to that of the 12% chromium steels (Type 430). In most tests there was no significant effect of aging temperature on corrosion resistance. Hydrogen embrittlement tests in 5% acetic acid saturated with sulfuric hydrogen at room temperature show the same degree of susceptibility as other high-strength martensitic stainless steels. All high-strength steels are subject to stress corrosion under certain stress conditions and in certain environments. Numerous severe tests have been conducted to evaluate the behavior of Custom 455 stainless in different environments, and to determine the effect of aging temperature on resistance to stress -corrosion cracking. These tests include U-bend specimens, direct tension specimens, C-rings and precracked cantilever beam specimens. Environments have included marine atmospheres, 20% salt spray, and 3-1/2% sodium chloride solutions. All tests have shown that Custom 455 stainless has inherently good resistance to stress-corrosion cracking, and that this resistance improves markedly as aging temperature is increased. For optimum corrosion resistance, surfaces must be free of scale and foreign particles and finished parts should be passivated.


Elevated Temperature Use

Custom 455 stainless has displayed excellent resistance to oxidation up to approximately 1100 °F. Long-term exposure to temperatures between about 600-900 °F can result in reduced toughness in precipitaiton hardenable stainless steels. The reduction in toughness can be minimized in some cases by using higher aging temperatures. Short exposures to elevated temperatures can be considered, provided the maximum temperature is at least 50 °F less than the aging temperature.


Physical Properties

(Condition H 950)
Specific gravity.............................................. 7.76
Density
lb/cubic in .................................................... 0.280
kg/cubic m .................................................... 7760
Modulus of Elasticity (E)
ksi..................................................... 29.0 x 10(3)
MPa....................................................200 x 10(3)

Modulus of Rigidity (G)
ksi ................................. 11.0 x 10(3)
Mpa x 10(3).................. 75.8 x 10(3)
Poisson's Ration...........................0.30

Mean Coefficient fo thermal expansion

Temperature

10(-6)/°F

10(-6)/K

72 °F to

22 °C to

200

93

5.90

10.6

300

149

6.03

10.9

500

260

6.20

11.20

700

371

6.45

11.6

900

482

6.68

12.0

Thermal Conductivity

Test
Temperature

Btu-in/ft²-h-°F

W/m-K

°F

°C

212

100

125

18.0

392

200

137

19.7

572

300

148

21.3

752

400

162

23.4

932

500

172

24.7

Electrical Resistivity

Condition

Ohm-cir-mil/ft

Microhm/mm

A

545

906

H 950

456

758


Heat Treatment

Condition A
(Solution Treated or Annealed): Heat to 1500/1550 °F, and cool rapidly. Water quenching is preferred for small sections. Custom 455 stainless will normally be supplied from the mill in the annealed condition, ready for the one-step hardening treatment.

Condition H 900, H 950, H 1000, H 1050
(Precipitation or Age Hardened): The high strength levels of Custom 455 are derived from a single precipitation-hardening treatment consisting of heating to a selected temperature between 900/1050 °F, holding for 4 hours and air cooling

Average Longitudinal Size Change (Contracting)
Solution-treated to aged condition

Condition

Contraction
in./in.

H 900

0.0007

H 950

0.0009

H 1000

0.0012

Cleaning
Descaling following forging and annealing can be accomplished by acid cleaning or grit blasting. The acic treatment consists of 2 minutes in 50% by volume muriatic acid at 180 °F, followed by 4 minutes in a mixture of 15% by volume nitric acid, plus 3% by volume hydrofluoric acid at room temperature. Repeat cleaning procedure as neccessary but decrease the times by 50% (i.e., 1 and 2 minutes, respectively). The heat tint from aging can be removed by polishing, vapor blasting or pickling 4 to 6 minutes in a mixture of 15% by volume nitric acid, followed by a water rinse. Repeat the acid cleaning procedure if necessary, but decrease the time by 2 to 3 minutes. Desmut in 20% by volume nitric acid at room temperature. After acid cleaning, bake 1 to 3 hours at 300/350 °F to remover hydrogen.


Workability

Hot working
Custome 455 stainless is easily forged within the temperature range fo 1650/2300 °F. For optimum mechanical properties, material to be forged should be heated uniformly to 1900/2100 °F and soaked at heat; fnishing temperature should be within the range of 1500/1700 °F to obtain an optimum grain size and properties after heat treating. Cool forging in air to rom temperature and anneal.

Cold working
Cold working is readily performed despite the fact that Custom 455 stainless is martensitic in the annealed condition, and has a hardness of Rockwell C 30/35. Deep drawing or sketching operations will required intermediate anneals because the elongation tends to be localized. For other cold-forming operations such as cold drawing and cold rolling, the work-hardening rate in the annealed condition is extremely low allowing considearble cold working without intermediate annealing. Cold-heading and warm-heading operations are also easily performed. Cold working prior to aging results in even higher tensile and yield strengths in the hardened condition.

Spring Properties
Wire in the annealed or lightly drawn condition and annealed strip can be aged for 2 to 4 hours at 900°F (482°C) to achieve a tensile strength in excess of 250 ksi (1742 MPa). As such, Custom 455 stainless can be used in relatively large diameters and thicknesses and still have good spring characteristics. This greatly expands the range of sizes of corrosion-resistant springs available to designers.
Custom 455 stainless can also be extensively cold worked prior to aging to achieve even higher levels of strength. Extensive cold working reduces the aging time required to reach maximum mechanical properties. Therefore, cold-drawn spring wire and cold-rolled strip in Condition C need only be aged for 1/2 hour at 850°F (454°C).

Diameter

Nominal
Cold-Drawn
Tensile Strength

Age-Hardened Tensile
Strength

inches

mm

ksi

MPa

MIN

MAX

MIN

MAX

Machining
Custom 455 stainless have been machined successfully using the same practices required for other high-strength alloys; i.e., rigid tool and work supports, slower speeds, positive cuts and adequate amounts of coolant. The machining characteristics of Custom 455 stainless are similar to those of the nickel maraging steeels. When using carbide tools , surface speed feet/minute can be increased between 2 to 3 times over the high speed suggestions. Feeds can be increased between 50 and 100%.

High Speed Tool

Turning-
Cut-Off
And
Forming

Cut-Off
Tool
Width

1/16"

SFPM
IPR

60
.001

1/8"

SFPM
IPR

60
.0015

1/4"

SFPM
IPR

60
.002

1/2"

SFPM
IPR

60
.0015

Form
Tool
Width

1"

SFPM
IPR

60
.001

1-1/2"

SFPM
IPR

60
.0007

Drilling

Drill
Dia.

1/4"

SFPM
IPR

50
.004

3/4"

SFPM
IPR

50
.008

Reaming

Under 1/2"

SFPM
IPR

60
.003

Over 1/2"

SFPM
IPR

60
.008

Die
Threading

T.P.I

3-7½

SFPM

5-12

8-15

SFPM

8-15

Over 16

SFPM

10-20

Welding
Custom 455 stainless can be satisfactorily welded by the shielded fusion and resistance welding processes. Oxyacetylene welding is not recommended, since carbon pickup in the weld may occur. Preheating is not required to prevent cracking during the welding of this alloy. Normally, welding in the solution-annealed condition is satisfactory; however, where high welding stresses are anticipated, it may be advantageous to weld in the overaged (aged at 1150 °F) condition. If welded in the solution-annealed condition, the alloy can be directly aged to the desired strength level after welding. However, the optimum combination of strength, ductitlity and corrosion resistance is obtained by solution annealing the welded part before aging. If welded in the overaged condition, the part should be solution annealed before aging.


Typical Mechanical Properties

Typical Room Temperature Mechanical Properties
Bar, 1"(25.4mm) section

Condition

0.2%
Yield
Strength

Ultimate
Tensile
Strength

Notch
Tensile
Strength
K(t)=10

%
Elong.
in 4D

%
Reduction
of Area

Rockwell
C
Hardness

Charpy
V-Notch
Impact
Strength

ksi

MPa

ksi

MPa

ksi

MPa

ft-lb

J

A

115

793

140

965

--

--

12

50

31

--

--

H 900

220

1516

230

1585

250

1723

10

45

48

8

11

H 1000

195

1344

205

1413

250

1723

12

45

45

12

16

H 1050

175

1206

190

1309

250

1723

14

50

40

25

34

Typical Elevated Temperature
Tensile properties, condition H950

Test
Temperature

0.2%
Yield
Strength

Ultimate
Tensile
Strength

%
Elongation
in 4D

%
Reduction
of Area

Room Temp.
Rockwell C
Hardness
after test

°F

°C

ksi

MPa

ksi

MPa

Room

220

1517

230

1586

12

50

48

600

316

185

1276

195

1345

12

50

48

800

427

163

1124

175

1207

14

60

48

1000

538

110

758

130

896

18

70

48

Typical Elevated Temperature
Tensile properties, condition H1000

Test
Temperature

0.2%
Yield
Strength

Ultimate
Tensile
Strength

%
Elongation
in 4D

%
Reduction
of Area

Room Temp.
Rockwell C
Hardness
after test

°F

°C

ksi

MPa

ksi

MPa

Room

195

1345

205

1413

14

55

44

600

316

165

1138

174

1200

14

60

44

800

427

163

1020

154

1062

15

65

44

1000

538

110

758

118

814

20

75

44

Typical Stress Rupture Strength

Test Temperature

Condition

Stress for rupture in

°F

°C

ksi

MPa

ksi

MPa

ksi

MPa

800

427

H 950

142

979

117

807

91

627

900

482

H 950

109

752

82

565

54

372

Custom 455 - Current Inventory Stock

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