17-4 PH stainless steel (UNS S17400 / ASTM A747 Grade CB7Cu-1) is a martensitic precipitation-hardening alloy containing approximately 15.0% to 17.5% Chromium, 3.0% to 5.0% Nickel, and 3.0% to 5.0% Copper. It provides high yield strength, excellent wear resistance, and corrosion performance comparable to 304 austenitic stainless steel in atmospheric and mild chemical environments.
Jining Wabon Precision Metal Co., Ltd. manufactures custom 17-4 PH components using 100% silica sol investment casting. This process yields near-net-shape parts with surface roughness of Ra 3.2 um to Ra 6.3 um and linear tolerances conforming to ISO 8062-3 DCTG5, significantly reducing or eliminating secondary machining.
Manufacturing Process
Our casting facility operates an automated silica sol process route specifically optimized to control alloy segregation and gas porosity in copper-bearing stainless steels:
Tooling Design & Injection: Aluminum tooling manufactured via 5-axis CNC machining. Pattern wax is injected at controlled temperature (T = 62 deg C +/- 2 deg C) and pressure to ensure dimensional repeatability.
Robotic Shell Building: Multi-layer ceramic shell construction using pure silica sol slurry and zircon flour/sand for face coats, followed by mullite backing coats. Shell drying is executed in climate-controlled rooms (22 deg C +/- 1 deg C, relative humidity 60% +/- 5%).
Autoclave Dewaxing & High-Temperature Firing: Steam autoclave dewaxing at 8 bar pressure. Ceramic shells are pre-fired at 1050 deg C for 2 hours to remove organic residues and sinter the ceramic binder.
Medium-Frequency Induction Melting: Certified raw materials and master alloys are melted in medium-frequency induction furnaces. Melt chemistry is verified via Optical Emission Spectrometry (OES) prior to pouring. Deoxidation and argon purging are applied prior to pouring at 1580 deg C to 1620 deg C.
Knockout, Shot Blasting & Gate Cutoff: Mechanical shell removal followed by high-pressure steel shot blasting and plasma or saw gate removal.
Materials and Technical Specifications
Chemical Composition Limits (ASTM A747 CB7Cu-1 vs. Wrought 17-4 PH)
|
Element |
ASTM A747 CB7Cu-1 (Cast Grade) |
UNS S17400 (Wrought 17-4 PH) |
Wabon Internal Control Range |
|
Chromium (Cr) |
15.50 - 17.50% |
15.00 - 17.50% |
16.00 - 17.00% |
|
Nickel (Ni) |
3.60 - 4.60% |
3.00 - 5.00% |
4.00 - 4.50% |
|
Copper (Cu) |
2.80 - 3.20% |
3.00 - 5.00% |
3.00 - 3.50% |
|
Niobium (Nb) + Ta |
0.15 - 0.45% |
0.15 - 0.45% |
0.25 - 0.35% |
|
Manganese (Mn) |
Max 1.00% |
Max 1.00% |
Max 0.70% |
|
Silicon (Si) |
Max 1.00% |
Max 1.00% |
Max 0.60% |
|
Carbon (C) |
Max 0.07% |
Max 0.07% |
0.03 - 0.05% |
|
Phosphorus (P) |
Max 0.04% |
Max 0.04% |
Max 0.025% |
|
Sulfur (S) |
Max 0.03% |
Max 0.03% |
Max 0.015% |
Mechanical Properties by Heat Treatment Condition
|
Heat Treatment Condition |
Solution Temp (deg C) |
Aging Temp (deg C) & Hold Time |
Tensile Strength Rm (MPa) min. |
Yield Strength Rp0.2 (MPa) min. |
Elongation A5 (%) min. |
Hardness (HRC / HB) |
|
Condition A (Solutionized) |
1040 +/- 15 (Air/Oil Quench) |
None |
N/A (Not for service) |
N/A |
N/A |
32 - 38 HRC |
|
Condition H900 |
1040 +/- 15 |
480 +/- 10 deg C / 1 hour |
1310 |
1170 |
10% |
40 - 47 HRC |
|
Condition H1025 |
1040 +/- 15 |
550 +/- 10 deg C / 4 hours |
1070 |
1000 |
12% |
35 - 42 HRC |
|
Condition H1075 |
1040 +/- 15 |
580 +/- 10 deg C / 4 hours |
1000 |
860 |
13% |
32 - 38 HRC |
|
Condition H1150 |
1040 +/- 15 |
620 +/- 10 deg C / 4 hours |
930 |
725 |
16% |
28 - 37 HRC |
|
Condition H1150-D (Double) |
1040 +/- 15 |
620 deg C / 2h + 620 deg C / 2h |
900 |
725 |
18% |
24 - 33 HRC |
Standard Manufacturing Tolerances
|
Parameter |
Standard Capability |
Precision Capability (On Request) |
|
Linear Dimensional Tolerance |
ISO 8062-3 DCTG5 / VDG P695 D2 |
ISO 8062-3 DCTG4 (requires dedicated tooling fine-tuning) |
|
As-Cast Surface Roughness |
Ra 3.2 - Ra 6.3 um (Silica Sol) |
Ra 1.6 - Ra 3.2 um (Electropolished or Machined) |
|
Minimum Wall Thickness |
1.5 mm (localized areas less than 50 mm) |
2.0 mm (general wall thickness) |
|
Weight Range |
0.02 kg to 45.0 kg |
Up to 60.0 kg |
Key Product Features
Precipitation Hardening Mechanism:
High mechanical strength is achieved via sub-microscopic copper-rich phase (epsilon-Cu) precipitation within the martensitic matrix during aging, avoiding the severe thermal distortion associated with high-carbon martensitic steel quenching.
Dimensional Stability in Heat Treatment:
Volumetric shrinkage during aging from Condition A to Condition H900 is minimal (approx 0.0004 to 0.0006 in/in), permitting tight machining prior to final thermal processing.
Corrosion Resistance in Mild Media:
Demonstrates atmospheric corrosion resistance superior to 410/420 series martensitic stainless steels and comparable to 304 in urban/industrial atmospheres and dilute nitric acid.
High Fatigue & Wear Resistance:
Hardness up to 47 HRC in H900 condition offers high resistance to adhesive wear, cavitational erosion, and high-cycle mechanical fatigue.
Typical Applications
High-pressure valve bodies, butterfly valve discs, pump impellers, control valve trim, hydraulic actuator cylinders, and manifold blocks operating under severe pressure differentials.
Flight control actuators, door latch mechanisms, cargo handling hooks, missile fin mounts, and structural bracketry requiring high strength-to-weight ratios.
Propeller shaft couplings, winch components, underwater instrument housings, cable connectors, and pump casings exposed to brackish or marine environments.
Robotic end-effector arms, high-load wear plates, gear housings, centrifuge rotors, mix heads, and food processing cutter heads.
Machining and Secondary Operations
17-4 PH exhibits work-hardening characteristics during machining. To optimize tool life and surface finish, machining strategies should be matched to material heat treatment condition:
Machining Best Practice: Machine 17-4 PH in Condition A or Condition H1150 for maximum material removal rates and lower tool wear. If tight tolerances (less than IT7) are required, perform rough machining in Condition A, heat treat to the final target condition (e.g., H900), and perform final finish grinding or hard turning.
CNC Machining Services: In-house 3-, 4-, and 5-axis CNC machining centers, turning centers, and wire EDM for features requiring tolerances down to +/- 0.008 mm.
Surface Finishing: Passivation (ASTM A967 Citric/Nitric), electropolishing, bead blasting, hand polishing up to mirror finish, and zinc-nickel plating.
Welding & Assembly: 17-4 PH can be welded using GTAW (TIG) or GMAW (MIG) with matching ER630 filler metal. Post-weld heat treatment (solution anneal + aging) is required to restore full mechanical properties across the heat-affected zone (HAZ).
Quality Control and Inspection
Every casting heat lot is traceable from raw melt to final dispatch under ISO 9001:2015 and IATF 16949 quality management protocols.
|
Inspection Category |
Test Method / Equipment |
Applicable Standard / Acceptance Criteria |
|
Chemical Analysis |
Optical Emission Spectrometry (OES) per heat melt |
ASTM A747 Grade CB7Cu-1 chemical limits |
|
Mechanical Testing |
Tensile, Yield, Elongation, Hardness (Rockwell/Brinell) |
ASTM A370 / ASTM E8 |
|
Non-Destructive Testing (NDT) |
Liquid Penetrant Inspection (LPI) |
ASTM E1417 / ASTM E165 (Level II certified inspectors) |
|
Internal Defect Inspection |
Radiographic Testing (X-Ray) / Digital Radiography |
ASTM E192 / ASTM E446 reference radiographs |
|
Dimensional Verification |
3D CMM Inspection, Optical 3D Scanner, Gauge Pin/Go-NoGo |
ISO 8062-3 / Customer Engineering Drawing |
|
Microstructure Verification |
Metallographic examination for ferrite content control |
Delta-ferrite content less than 10% to prevent impact toughness loss |
Certificates Provided: EN 10204 3.1 Material Test Certificate (MTC), NDT Examination Reports, CMM Inspection Reports, and Certificate of Conformance (CoC) shipped with every batch.
OEM and Custom Manufacturing
We work directly with OEM engineering teams and tier-1 buyers to support custom component development across all production stages:
Design for Manufacturability (DFM):
Rapid solid modeling evaluation, draft angle optimization, wall thickness equalization, and solidification simulation (MAGMA) to prevent shrinkage porosity prior to tooling release.
Rapid Prototyping:
3D printed wax patterns or direct SLA pattern casting for functional prototype evaluation without investing in hard tooling. Prototype lead time: 10 to 15 business days.
Production Tooling:
Single-cavity or multi-cavity hardened aluminum/steel tooling engineered for high-volume repeatability (tooling life up to 100,000 shots).
What Buyers Should Provide for an RFQ
To receive an accurate commercial quotation and technical feasibility evaluation within 24 to 48 hours, please submit the following project parameters:
|
Item |
Required Document / Information |
Why It Matters |
|
1. Engineering Drawings |
2D Drawings (PDF/DWG with tolerances, GD&T, surface finish) + 3D CAD files (STEP, IGES, X_T) |
Allows precise dimensional evaluation and CAD volume calculation for melt weight. |
|
2. Material & Heat Treatment |
Material standard (e.g., ASTM A747 CB7Cu-1) + Heat Treatment Condition (H900, H1025, H1150, etc.) |
Determines raw material cost, heat treatment furnace cycles, and hardness testing specs. |
|
3. Annual & Order Quantities |
Estimated Annual Usage (EAU) and initial prototype / pilot batch quantity |
Determines tooling cavity layout (single vs. multi-cavity) and unit cost breakdown. |
|
4. Inspection & NDT Requirements |
Specific inspection levels (e.g., 100% LPI, X-Ray Class 2, EN 10204 3.1 MTC) |
Ensures compliance costs and non-destructive testing overhead are accurately factored into unit price. |
|
5. Machining & Surface Finish |
Specify as-cast areas vs. fully machined features; surface treatments (passivation, polishing) |
Determines fixture design, CNC machining cycle times, and secondary processing steps. |
Frequently Asked Questions
Q: How does 17-4 PH cast steel (ASTM A747 CB7Cu-1) compare to wrought 17-4 PH (UNS S17400)?
A: Cast 17-4 PH (CB7Cu-1) has minor chemical specification adjustments--specifically higher allowed silicon and slightly modified copper ranges--to optimize liquid metal fluidity during investment casting. When properly solution annealed and aged, cast 17-4 PH achieves mechanical properties within 90 to 95% of wrought 17-4 PH while allowing complex geometric features that cannot be cost-effectively machined from bar stock.
Q: Why is silica sol investment casting preferred over glass soluble/water glass casting for 17-4 PH?
A: Silica sol investment casting utilizes high-purity refractory materials that prevent surface carburization, reaction layers, and rough surface defects. Water glass casting often results in higher surface roughness (Ra 12.5 um) and inferior dimensional control. Silica sol achieves Ra 3.2 to 6.3 um as-cast finish and tighter linear tolerances (ISO 8062-3 DCTG5), which is essential for precision 17-4 PH engineering components.
Q: What heat treatment condition should I select for maximum impact toughness?
A: For applications subject to dynamic loading or sub-zero temperatures, select Condition H1150 or Condition H1150-D (Double Aged). These conditions provide higher impact toughness (Charpy V-Notch greater than 68 J) and elongation (greater than 16%) compared to Condition H900, which optimizes hardness (40 to 47 HRC) at the expense of ductility.
Q: Can Wabon supply fully machined, ready-to-assemble 17-4 PH castings?
A: Yes. Wabon operates in-house precision CNC machining facilities. We deliver finished 17-4 PH components complete with turning, milling, grinding, thread cutting, surface passivation, and 100% CMM inspection certificates.
