17-4 stainless is an age-hardening martensitic stainless combining high strength with the corrosion resistance of stainless steel. Hardening is achieved by a short-time, simple low-temperature treatment. Unlike conventional martensitic stainless steels, such as type 410, 17-4 is quite weldable. The strength, corrosion resistance and simplified fabrication can make 17-4 stainless a cost-effective replacement for high strength carbon steels as well as other stainless grades.
At the solution treating temperature, 1900°F, the metal is austenitic but undergoes transformation to a low-carbon martensitic structure during cooling to room temperature. This transformation is not complete until the temperature drops to 90°F. Subsequent heating to temperatures of 900-1150°F for one to four hours precipitation strengthens the alloy. This hardening treatment also tempers the martensitic structure, increasing ductility and toughness.
We stocks 17-4 in condition "A", and also stocks material in the hardened condition H1150.
Chemistry
|
|
Ni
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Cr
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Mo
|
Mn
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Cu
|
Si
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C
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Cb+Ta
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S
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P
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Fe
|
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MIN
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3.0
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15.0
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-
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-
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3.0
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-
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-
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5 x C
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-
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-
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-
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|
MAX
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5.0
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17.5
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0.50
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1.0
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5.0
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1.0
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0.07
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0.45
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0.03*
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0.04*
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Balance
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*0.025 max
Specifications
Inventory
17-4 Plate, 17-4 Round Bar, 17-4 Weld Wire
Common Trade Names
17-4 Stainless
Features
· High tensile strength and hardness to 600°F
· Corrosion resistant
· Excellent oxidation resistance to about 1100°F
· Creep-rupture strength to 900°F
Applications
· Gate valves
· Chemical processing equipment
· Pump shafts, gears, plungers
· Valve stems, balls, bushings, seats
· Fasteners
Physical Properties
Density: 0.282 lb/inch3
Melting Range: 2560 - 2625°F
Poisson's Ratio: 0.272
Electrical Resistivity: 463 Ohm-circ mil/ft
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Temperature, °F
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70
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212
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392
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572
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Coefficient of Thermal Expansion, in/in°F x 10-6
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-
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7.2
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7.5
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7.8
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|
Thermal Conductivity
Btu • ft/ft2 • hr • °F
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8.6
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9.2
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9.8
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10.4
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|
Modulus of Elasticity,
psi X 106
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29.0
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28.1
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27.0
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26.1
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* 70°F to indicated temperature.
Mechanical Properties
Representative Tensile Properties, Longitudinal Direction
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H900*
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H925
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H1025
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H1075
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H1100
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H1150
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HH1150
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H1150-M
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|
Ultimate Tensile Strength, ksi
|
200
|
190
|
170
|
165
|
150
|
145
|
140
|
125
|
|
0.2% Yield Strength, ksi
|
185
|
175
|
165
|
150
|
135
|
125
|
120
|
85
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|
Elongation % in 2" or 4XD
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14
|
14
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15
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16
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17
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19
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22
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22
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|
Reduction of Area, %
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50
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54
|
56
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58
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58
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60
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65
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68
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Hardness, Brinell (Rockwell)
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420 (C 44)
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409 (C42)
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352 (C 38)
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341 (C 36)
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332 (C 35)
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311 (C 33)
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294 (C 31)
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277 (C 27)
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|
Impact Charpy V-Notch, ft - lbs
|
15
|
25
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35
|
40
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45
|
50
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55
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100
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*For applications requiring greater impact toughness, aging for 4 hours develops typical properties UTS - 196 ksi, 0.2% YS - 181 ksi, Elongation in 2" - 14%, Reduction of Area - 52%, Hardness - Rockwell C 43, and Charpy V-notch impact - 20 foot-pounds
Heat Treament
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Designation
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Processing
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Condition A**
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Heated at 1900°F±25°F for 1/2 hour, air (Solution Treated) cooled or oil quenched to below 90°F. Normally performed at mill.
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H900
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Condition A material heated at 900°F±15°F for 1 hour and air cooled. Maximum hardness but low toughness. Sensitive to stress corrosion cracking. Heating 4 hours improves toughness with about 4 ksi reduction in tensile and yield.
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|
H925, H1025, H1075,
H1100, H1150
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Condition A material heated 4 hours at specific temperature, and air cooled.
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H1150
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Condition A material heated 4 hours at 1150F, air cooled, heated again for an additional 4 hours at 1150F and air cooled.
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H1150-M
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Condition A material heated at 1400°F±25°F for 2 hours, air cooled, then heated at 1150°F±15°F for 4 hours and air cooled.
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**For most applications, 17-4 stainless should not be used in Condition A. This is true even though the desired tensile strength may be provided by that condition. While the alloy is relatively soft in condition A, the structure is untempered martensite that has low fracture toughness and ductility, while poor resistance to stress-corrosion cracking. Superior service performance is assured by using 17-4 stainless in the heat-treated condition.
