Aerospace & Defense
Aerospace Fittings & Locking Mechanisms
Fittings, locking mechanisms and bearing housings in an alloy produced to aerospace bar specification AMS 5643.
CNC Machining Stainless Steel 17-4 PH For High-Strength, Hardenable Precision Parts
CNC Machining
Tight Tolerances
CNC machining material
Stainless Steel 17-4 PH (CNC) overview
Stainless Steel 17-4 PH is a heat-treatable stainless steel that is CNC machined in its soft condition and then hardened, giving parts very high strength with corrosion resistance comparable to 304 stainless steel. A single low-temperature heat treatment hardens the finished part without risk of cracking or distortion, and it can be set for maximum strength or for extra toughness. It suits highly loaded fittings and locking mechanisms, shafts and couplings, pump and valve parts, and tooling inserts across aerospace, defense, industrial equipment and oil and gas.
How Stainless Steel 17-4 PH is manufactured
Stainless Steel 17-4 PH parts are made by CNC machining, which removes material from solid bar using precision cutting tools on multi-axis machines. The bar is supplied solution treated, a condition that machines readily, and the finished part is then aged with a single low-temperature heat treatment to the condition on the drawing. Aging hardens the part without risk of cracking or distortion, with only a slight, predictable contraction, and because there is no tooling to make, the same program runs a single prototype or a repeat production batch.
- Machining envelope
- 1000 × 600 × 500 mm
- Lead time
- 5-7 business days
- Tolerance
- ±0.025 mm typical
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Upload CAD files and drawings to Forge Labs Steam, and our engineers review Stainless Steel 17-4 PH parts for tolerances, tool access and finish so issues are fixed before production.
Industry applications
Industry applications for Stainless Steel 17-4 PH
Stainless Steel 17-4 PH combines high strength with corrosion resistance comparable to 304 stainless steel. It can be heat treated to multiple hardness conditions and stays dimensionally stable through aging, which suits it to demanding applications. From rapid prototyping to production runs, teams rely on Stainless Steel 17-4 PH to maintain tight tolerances while reducing assembly complexity through consolidated part designs.
Aerospace and defense programs trust it for strength-critical hardware, and industrial equipment and oil and gas operators rely on it when uptime matters. It welds readily with matching filler, and welded assemblies are aged afterward to restore full properties.
The aging temperature sets the balance of properties. H900 gives the highest strength and hardness for compact, highly loaded parts, while higher aging temperatures such as H1025 and H1150 trade some strength for toughness and ductility. Specify the condition on the drawing, along with any features to be finished after aging.
Where a part carries internal channels or comes in small lots of awkward shapes, Forge Labs prints 17-4 PH by DMLS and machines only the threads, bores and sealing faces that need it. Parts where nearly every surface carries a machining tolerance are still best cut from bar.
Power Generation
Threaded Valve & Engine Hardware
Valve heads and seal protectors finished with cut threads, with one lot shipped 5 business days early.
Industrial Equipment
Precision Shafts, Couplings & Pump Parts
Shafts, couplings and pump parts, aged to resist stress corrosion in marine atmospheres.
Oil, Gas & Process
Valve Stems, Trim & Process Fittings
Valve stems, trim and fittings that resist sulfuric, acetic and formic acids far better than 304 stainless.
Aerospace & Defense
Aerospace Fittings & Locking Mechanisms
Aerospace and defense teams use machined Stainless Steel 17-4 PH for fittings, locking mechanisms, latch and hinge parts and bearing housings, where small parts carry high loads and must resist corrosion in service. Aircraft and missile fittings are among its main uses, and 17-4 PH bar is produced to the aerospace specification AMS 5643.
- Fittings and brackets
- Locking, latch and hinge mechanisms
- Bearing housings
Power Generation
Threaded Valve & Engine Hardware
Power generation equipment makers choose 17-4 PH for valve heads, seal protectors and other small engine parts that need hardness and strength once aged. One lot of seal protectors, printed and then tapped, shipped 5 business days ahead of the promised date, and a redesigned valve head moved from 316L to 17-4 PH with a machined thread added, then was reordered in a larger lot.
- Valve heads
- Valve seal protectors
- Tapped and threaded engine parts
Industrial Equipment
Precision Shafts, Couplings & Pump Parts
Industrial equipment makers machine Stainless Steel 17-4 PH into precision shafts, couplings, pump shafts and valve parts that carry high loads in corrosive service. The aging condition is chosen for the environment: in seacoast air, stressed 17-4 PH aged at H1025 and above has gone more than 25 years without stress corrosion failure, while H900 under the same load failed within 68 days.
- Precision shafts and couplings
- Pump shafts and valve parts
- Corrosion resistant mechanical components
Oil, Gas & Process
Valve Stems, Trim & Process Fittings
Petrochemical, petroleum and food processing plants use 17-4 PH for valve stems and trim, pump parts and fittings that need more strength than 300-series stainless steels provide. Aged 17-4 PH resists sulfuric, acetic and formic acids far better than annealed 304. For sour oil and gas service, NACE MR0175 accepts 17-4 PH only in the H1150-M or double-aged H1150 condition.
- Valve stems and trim
- Pump parts and fittings
- Process equipment hardware
Performance data
Technical performance for Stainless Steel 17-4 PH (CNC)
Values for wrought 17-4 PH (UNS S17400, Type 630) from ATI, AK Steel, Carpenter and North American Stainless data, with the source listed with each property. Strength rows are typical values for the H900, H1075 and H1150 aged conditions.
Mechanical performance
Mechanical properties
Stainless Steel 17-4 PH delivers exceptional mechanical performance, effectively handling demanding load conditions for high strength shafts and couplings, aerospace latch and hinge mechanisms, and fixtures and mold components.
Read the strength rows by condition. Every value is for an aged part, because producers advise against putting solution-treated bar into service.
PropertyValue
- Tensile Strength, H900ATI 17-4 alloy data
- 1340 MPa
- Yield Strength Rp0.2, H900ATI 17-4 alloy data
- 1240 MPa
- Elongation at Break (in 50 mm), H900ATI 17-4 alloy data
- 10 %
- Hardness, H900ATI 17-4 alloy data
- 43 HRC
- Tensile Strength, H1075ATI 17-4 alloy data
- 1070 MPa
- Yield Strength Rp0.2, H1075ATI 17-4 alloy data
- 930 MPa
- Hardness, H1075ATI 17-4 alloy data
- 36 HRC
- Tensile Strength, H1150ATI 17-4 alloy data
- 1000 MPa
- Yield Strength Rp0.2, H1150ATI 17-4 alloy data
- 860 MPa
- Hardness, H1150ATI 17-4 alloy data
- 31 HRC
- Modulus of ElasticityATI 17-4 alloy data
- 196 GPa
- Modulus of RigidityATI 17-4 alloy data
- 77.2 GPa
- Poisson's RatioAK Steel 17-4 PH bulletin
- 0.272
Material makeup
Physical properties
Consistent density and a uniform wrought structure keep critical features in tolerance and downstream finishing predictable.
The contraction row shows how much a part shrinks when aged from the solution-treated condition to H900. It is small and predictable, so finish allowances on tight features are set before machining, or the critical features are finished after aging. The composition rows are the ASTM A564 Type 630 limits.
PropertyValue
- Density, H900ATI 17-4 alloy data
- 7.81 g/cm³
- Density, H1150ATI 17-4 alloy data
- 7.86 g/cm³
- Contraction on Aging, Condition A to H900Carpenter and NAS bar data
- 0.04–0.06 %
- Chromium (Cr)ASTM A564 Type 630
- 15.00–17.50 wt%
- Nickel (Ni)ASTM A564 Type 630
- 3.00–5.00 wt%
- Copper (Cu)ASTM A564 Type 630
- 3.00–5.00 wt%
- Niobium + Tantalum (Nb + Ta)ASTM A564 Type 630
- 0.15–0.45 wt%
- Carbon (C)ASTM A564 Type 630
- ≤ 0.07 wt%
- Manganese (Mn)ASTM A564 Type 630
- ≤ 1.00 wt%
- Silicon (Si)ASTM A564 Type 630
- ≤ 1.00 wt%
- Phosphorus (P)ASTM A564 Type 630
- ≤ 0.040 wt%
- Sulfur (S)ASTM A564 Type 630
- ≤ 0.030 wt%
Heat performance
Thermal properties
Stainless Steel 17-4 PH maintains dimensional stability through temperature swings, and the expansion rows show how much a fit changes as a part warms across each range.
Design to the maximum service temperature, the point up to which the alloy keeps its high strength. Long exposure above it costs toughness, and short exposures should stay well below the aging temperature. Like other stainless steels it conducts heat poorly, and its conductivity rises with temperature.
PropertyValue
- Thermal Conductivity, H900 (21–100 °C)ATI 17-4 alloy data
- 17.8 W/m·K
- Thermal Conductivity, H900 (21–500 °C)ATI 17-4 alloy data
- 22.7 W/m·K
- Coefficient of Thermal Expansion (H900, 21–93 °C)AK Steel 17-4 PH bulletin
- 10.8 ×10⁻⁶/K
- Coefficient of Thermal Expansion (H900, 21–316 °C)AK Steel 17-4 PH bulletin
- 11.3 ×10⁻⁶/K
- Coefficient of Thermal Expansion (H900, 21–427 °C)ATI 17-4 alloy data
- 11.7 ×10⁻⁶/K
- Specific Heat (0–100 °C)AK Steel 17-4 PH bulletin
- 0.46 kJ/kg·K
- Maximum Service Temperature (high strength retained)ATI 17-4 alloy data
- 316 °C
Functional performance
Electrical properties
Stainless Steel 17-4 PH conducts electricity, so it suits grounded housings, fixtures and electrically integrated metal components, and its resistivity gives engineers reliable inputs for current flow and grounding models.
It is strongly ferromagnetic in every condition, including the solution-treated state, so it holds on magnetic fixtures and works with magnetic sensors, but it is not a choice for non-magnetic hardware.
PropertyValue
- Electrical Resistivity, H900ATI 17-4 alloy data
- 7.7×10⁻⁷ Ω·m
- Electrical Resistivity, H1150ATI 17-4 alloy data
- 8.6×10⁻⁷ Ω·m
- Electrical Conductivity, H900Calculated from ATI resistivity
- 1.30 MS/m
- Magnetic ResponseATI 17-4 alloy data
- Strongly ferromagnetic in all conditions
Compatibility data
Chemical properties
The table gives AK Steel immersion corrosion rates for 17-4 PH bar across the H925, H1025 and H1150 aged conditions, beside annealed Type 304. Lower is better. Where the range is wide, H1150 sits at the high end in sulfuric and hydrochloric acid and H925 in nitric acid. Use the rates to screen candidates before application testing.
It resists rural and mild industrial atmospheres in every aged condition, and seacoast exposure brings only light rusting and pitting, much like Type 304. AK Steel rates it well suited to many marine valve and pump parts, although stagnant sea water causes crevice attack. Passivate machined parts, and remove aging heat tint by polishing, blasting or pickling.
Chemical17-4 PH, H925 to H1150 (mm/a)Type 304 annealed (mm/a)
- Sulfuric acid 1%, 35 °C
- 17-4 PH, H925 to H1150 (mm/a)< 0.03
- Type 304 annealed (mm/a)0.71
- Sulfuric acid 5%, 35 °C
- 17-4 PH, H925 to H1150 (mm/a)0.10–0.23
- Type 304 annealed (mm/a)6.1
- Hydrochloric acid 0.5%, 35 °C
- 17-4 PH, H925 to H1150 (mm/a)0.05–0.41
- Type 304 annealed (mm/a)0.84
- Nitric acid 25%, boiling
- 17-4 PH, H925 to H1150 (mm/a)0.15–0.36
- Type 304 annealed (mm/a)0.05
- Nitric acid 65%, boiling
- 17-4 PH, H925 to H1150 (mm/a)2.0–3.2
- Type 304 annealed (mm/a)0.25
- Formic acid 10%, 80 °C
- 17-4 PH, H925 to H1150 (mm/a)0.05–0.13
- Type 304 annealed (mm/a)2.5
- Acetic acid 33%, boiling
- 17-4 PH, H925 to H1150 (mm/a)0.10–0.15
- Type 304 annealed (mm/a)7.6
- Phosphoric acid 20%, boiling
- 17-4 PH, H925 to H1150 (mm/a)0.03–0.05
- Type 304 annealed (mm/a)0.05
- Sodium hydroxide 30%, 80 °C
- 17-4 PH, H925 to H1150 (mm/a)0.13–0.20
- Type 304 annealed (mm/a)< 0.03
- Ammonium hydroxide 10%, boiling
- 17-4 PH, H925 to H1150 (mm/a)< 0.03
- Type 304 annealed (mm/a)< 0.03
- Cola soft drink syrup, 35 °C
- 17-4 PH, H925 to H1150 (mm/a)< 0.03
- Type 304 annealed (mm/a)< 0.03
- Salt, sugar and vinegar, boiling
- 17-4 PH, H925 to H1150 (mm/a)< 0.03
- Type 304 annealed (mm/a)< 0.03
Compliance
Compliance profile
Producers make 17-4 PH bar to ASTM A564 Type 630, which sets the minimum properties for each aged condition, and to AMS 5643, its aerospace counterpart for bar and forgings.
StandardStatus
- ASTM A564 / ASME SA-564 (Type 630, UNS S17400)Bar, wire and shapes specification for 17-4 PH; H900 minimums 1310 MPa UTS, 1170 MPa yield, 10% elongation
- ATI / Carpenter listed specification
- AMS 5643Aerospace specification for 17-4 PH bars, forgings, tubing and rings
- ATI listed specification
Related materials
Compare Stainless Steel 17-4 PH (CNC) with similar materials
Resources
Datasheets and design resources
Datasheets, design guidance and supplier documentation for Stainless Steel 17-4 PH (CNC).
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Stainless Steel 17-4 PH (CNC) datasheetDesign guidelines
Tolerance, wall thickness and finishing guidance for machined parts.
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Advanced Manufacturing
Built with Precision CNC Machining Technology
Stainless Steel 17-4 PH is manufactured using advanced CNC machining technology, ensuring optimal material properties and dimensional accuracy. Machined parts keep the full wrought strength of the bar.
- Surface finish
- As-machined Ra 1.6-3.2 µm; precision finish Ra 0.4 µm
- Production capacity
- Large envelope for efficient manufacturing of multiple parts or assemblies
- Quality control
- In-process monitoring and batch traceability for consistent part quality and material properties
- Heat treatment
- Aging heat treatment
- Colours & finishes
- Deburring, passivation and grinding
Frequently Asked Questions
Frequently asked questions about Stainless Steel 17-4 PH (CNC)
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- Stainless Steel 17-4 PH combines high strength with corrosion resistance comparable to 304 stainless steel, can be heat treated to multiple hardness conditions and stays dimensionally stable after aging, which suits aerospace and defense applications. In the H900 condition it reaches a typical 1340 MPa tensile strength, 1240 MPa yield strength and 43 HRC hardness, and it keeps its high strength to about 316 °C.
- Stainless Steel 17-4 PH is machined from solid bar in the solution-treated condition, then aged to the condition on the drawing. Material aged to H900 cuts at roughly half the speed, which is why parts are machined first. Aging to H900 contracts a part by about 0.04-0.06%, so allowances on tight features are planned before machining. Typical tolerance is ±0.025 mm, down to ±0.010 mm on request, with an as-machined finish of Ra 1.6-3.2 µm.
- Stainless Steel 17-4 PH is used across aerospace, defense, industrial equipment, power generation and oil and gas for fittings, locking, latch and hinge mechanisms, bearing housings, high strength shafts and couplings, pump parts, valve stems and trim, and corrosion resistant mechanical components.
- Stainless Steel 17-4 PH reaches high strength and hardness from a single low-temperature aging treatment, so parts are machined in the soft condition and hardened afterward without risk of cracking or distortion. It can be aged to several conditions to balance strength against toughness, welds readily with matching filler, and performs in challenging industrial environments.
- Choose H900 for maximum strength and hardness, about 1340 MPa tensile strength and 43 HRC typical. Choose H1025 or higher where chlorides and stress corrosion cracking are a risk; H1075, for example, gives about 1070 MPa tensile strength and 36 HRC. Choose H1150 for more toughness, at about 1000 MPa tensile strength and 31 HRC. For sour oil and gas service, NACE MR0175 accepts 17-4 PH only in the H1150-M or double-aged H1150 condition. State the condition on the drawing.
- Yes. Stainless Steel 17-4 PH is strongly ferromagnetic in every condition, including the solution-treated state and all aged conditions, so it works with magnetic fixturing and sensors but is not suitable for non-magnetic hardware.
- Stainless Steel 17-4 PH requires controlled heat treatment for its target properties, and its higher cutting forces increase cycle time compared with aluminum. Its corrosion resistance is comparable to 304, with crevice attack in stagnant sea water, and in the H900 condition it is susceptible to chloride stress corrosion cracking, so wet chloride service calls for H1025 or higher.
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