Stainless steel material 17-4PH

17-4PH is readily hot forged. During heat treatment or forging, protective atmospheres containing carbon or nitrogen should be avoided. These elements can be absorbed into the steel surface and give soft austenitic skin. If a protective atmosphere is required argon or helium is recommended.

The alloy also possesses good toughness when welded, while short low-temperature heat treatments reduce warping and scaling. Additionally, 17-4PH is easy to machine and fabricate.

Thanks to the beneficial properties, 17-4PH finds use in various industries. Typical parts include mechanical seals, oil patch, and pump shafts.

 

Machinability 17-4PH can be machined in both the solution annealed condition and the precipitation hardened condition. Because the final heat treatment temperature is low, 17-4PH can be machined to final dimension in the annealed condition and then aged without significant dimensional change or scaling unless the component is large, when allowance should be made for contraction on aging.
In the annealed condition machining is only marginally different from 300 series austenitic stainless steels. In the H900 condition the machining rate is 60% of that for annealed material.

CHEMICAL COMPOSITION

GRADES	SS316	17-4PH
Carbon	0.05	0.06
Manganese	2	0.9
Phosphorous	0.045	0.03
Sulfur	0.03	0.02
Silicon	N/A	0.9
Copper, columbium, and Tantalum	N/A	4
Molybdenum	2.1	N/A
Nickel	8	4
Chromium	18	17.5

 
hysical Properties of Stainless Steel 17-4PH

Property	Imperial	Metric
Melting Range	2560-2625 °F	1404-1440 °C
Specific Heat	0.11 Btu/lb.-°F	460 Joules/gg-K
Specific Density	0.282 lb/in3	7.8 g/cm3
Electrical Resistivity	38.6 µΩ in	98 µΩ cm
Linear Coefficient of Thermal Expansion (70 °F to 200 °F) (21 °C to 93 °C)	6 [in/in/°F·106]	10.8 [μm/m·°C]
Linear Coefficient of Thermal Expansion (70 °F to 400 °F) (21 °C to 204 °C)	6 [in/in/°F·106]	10.8 [μm/m·°C]
Linear Coefficient of Thermal Expansion (70 °F to 600 °F) (27 °C to 316 °C)	6.2 [in/in/°F·106]	11.2 [μm/m·°C]
Linear Coefficient of Thermal Expansion (70 °F to 800 °F) (21 °C to 427 °C)	6.3 [in/in/°F·106]	11.2 [μm/m·°C]
Thermal Conductivity (@ 300 °F) (@ 149 °C)	124 Btu/(hr/ft²/in/°F)	17.9 [W/m-K]
Thermal Conductivity (@ 500 °F) (@ 260 °C)	135 Btu/(hr/ft²/in/°F)	19.5 [W/m-K]
Thermal Conductivity (@ 860 °F) (@ 460 °C)	156 Btu/(hr/ft²/in/°F)	22.5 [W/m-K]
Thermal Conductivity (@ 900 °F) (@ 482 °C)	157 Btu/(hr/ft²/in/°F)	22.6 [W/m-K]
Poisson’s Ratio (H900 Condition)	0.272	0.272
Modulus of Elasticity (H900 Condition)	28 x 106 ksi	197 x 103 MPa
Modulus of Rigidity in Torsion	9.68 x 103 ksi	67 x 103 MPa

Stainless Steel 17-4PH Mechanical Properties

Property	Imperial	Metric
Ultimate Tensile Strength	23,300 psi	160 MPa
Yield Strength (0.02%)	16,680 psi	115 MPa
Elongation (% in 2’’)	5%	5%
Rockwell Hardness C	35	35

Heat Treatment

Stainless Steel 17-4PH is available in the solution annealed condition at 1900 °F (1038 °C) and then air-cooled to 90 °F (32 °C).

However, additional heat treatments can produce various hardness and toughness levels. The most common treatments are listed in the table below.

Condition	Temperature [± 15 °F (± 8.4 °C)]	Cooling Method and Duration
H 900	900 °F (482 °C)	Air cooling for 1 hour
H 925	925 °F (496 °C)	Air cooling for 4 hours
H 1025	1025 °F (551 °C)	Air cooling for 4 hours
H 1075	1075 °F (580 °C)	Air cooling for 4 hours
H 1100	1100 °F (593 °C)	Air cooling for 4 hours
H 1150	1150 °F (621 °C)	Air cooling for 4 hours
H 1150 + 1150	1150 °F (621 °C) followed by 1150 °F (621 °C)	Air cooling for 4 hours followed by Air cooling for 4 hours
H 1150-M	1400 °F (760 °C) followed by 1150 °F (621 °C)	Air cooling for 2 hours followed by Air cooling for 4 hours