17-4

17-4

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.

Rolled Alloys stocks 17-4 in condition "A", and also stocks material in the hardened condition H1150.

Chemistry

 NiCrMoMnCuSiCCb+TaSPFe
MIN 3.0 15.0 - - 3.0 - - 5 x C - - -
MAX 5.0 17.5 0.50 1.0 5.0 1.0 0.07 0.45 0.03 0.04 Balance

Specifications

AMS 5604AMS 5643AMS 5825
ASME SA 564ASME SA 693ASME SA 705ASME Type 630
ASTM A 564ASTM A 693ASTM A 705ASTM Type 630
Condition A - H1150
ISO 15156-3
NACE MR0175
S17400
UNS S17400
W. Nr./EN 1.4548

Inventory

17-4 Plate, 17-4 Round Bar, 17-4 Welding Products

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

Temperature, °F 70 212 392 572
Coefficient of Thermal Expansion, in/in°F x 10-6 - 7.2 7.5 7.8
Thermal Conductivity
Btu • ft/ft2 • hr • °F
8.6 9.2 9.8 10.4
Modulus of Elasticity,
psi X 106
29.0 28.1 27.0 26.1

* 70°F to indicated temperature.

Mechanical Properties

Representative Tensile Properties, Longitudinal Direction

  H 900* H 925 H 1025 H 1075 H 1100 H 1150 H 1150-M
Ultimate Tensile Strength, ksi 200 190 170 165 150 145 125
0.2% Yield Strength, ksi 185 175 165 150 135 125 85
Elongation % in 2" or 4XD 14 14 15 16 17 19 22
Reduction of Area, % 50 54 56 58 58 60 68
Hardness, Brinell (Rockwell) 420 (C 44) 409 (C42) 352 (C 38) 341 (C 36) 332 (C 35) 311 (C 33) 277 (C 27)
Impact Charpy V-Notch, ft - lbs 15 25 35 40 45 50 100

*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

Designation Processing
Condition A** 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.
H 900 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.
H 925, H 1025, H 1075,
H 1100, H 1150
Condition A material heated 4 hours at specific temperature, and air cooled.
H 1150-M 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.

**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.