CF8M is the cast equivalent of wrought AISI 316 stainless steel, standardized under ASTM A351/A351M (Standard Specification for Castings, Austenitic, for Pressure-Containing Parts). Formulated with 18% chromium, 11% nickel, and 2.0-3.0% molybdenum, CF8M exhibits superior resistance to pitting, crevice corrosion, and chloride-induced stress corrosion cracking compared to non-molybdenum grades like CF8 (304 equivalent).
Jining Wabon Precision Metal Co., Ltd. manufactures custom CF8M investment castings using 100% silica sol process tooling. By using silica sol slurry rather than water glass binders, we eliminate surface pitting and maintain linear tolerances within ISO 8062-3 CT4 to CT6, producing pressure-tight components for corrosive fluid handling, marine propulsion, chemical processing, and food production equipment.
Material Standard: ASTM A351 Grade CF8M / UNS J92900 (EN 10283 1.4408 / GX5CrNiMo19-11-2)
Casting Process: Silica Sol Investment Casting (Lost Wax Process)
As-Cast Surface Roughness: Ra 3.2 um - Ra 6.3 um (Ra 125 - 250 uin)
Unit Weight Range: 0.05 kg to 80 kg (0.1 lbs to 176 lbs)
Production Capability: Custom OEM components from 2D drawings (DWG, DXF, PDF) and 3D CAD models (STEP, IGES, X_T)
Manufacturing Process
Our 30,000 square meter facility executes a 12-step silica sol investment casting workflow optimized for austenitic stainless steels:
Production Workflow
• Tooling & Wax Pattern Creation
• Pattern Tree Assembly
• Silica Sol Dipping & Stucco
• Autoclave Dewaxing & High-Temp Firing
• Induction Melting & Spectrometer Check
• Gravity Pouring & Natural Cooling
• Knockout & Gating Cut-Off
• Solution Annealing Heat Treatment
• Shot Blasting & Cleaning
• CNC Precision Machining
• Passivation & Surface Finishing
• Final Quality Inspection & Packaging
Key Steps Detail
• Tooling & Wax Pattern Creation: Aluminum dies inject high-purity pattern wax under controlled pressure and temperature to ensure repeatable dimensions without internal shrinkage cavities.
• Cluster Assembly: Patterns are mounted on central wax runners configured to maintain balanced metal flow and feeding during solidification.
• Silica Sol Shell Building: Clusters undergo 5 to 7 dip cycles in silica sol binders mixed with zircon and fused silica refractory flour, followed by stuccoing in climate-controlled drying rooms (22 degrees C +/- 2 degrees C, 50-60% RH).
• Autoclave Dewaxing & High-Temperature Firing: Shells are dewaxed in a steam autoclave at 8 bar (170 degrees C), then fired at 1000 degrees C to 1080 degrees C to burn out binder residues and sinter the ceramic structure.
• Induction Melting & Pouring: CF8M alloy charge is melted in medium-frequency induction furnaces. Chemical analysis via optical emission spectroscopy (OES) is verified before gravity pouring into preheated ceramic molds.
• Knockout & Gating Removal: After natural cooling, shells are broken off with pneumatic hammers, and gate runners are removed via plasma cutting or abrasive saw.
• Heat Treatment (Solution Annealing): Castings are heated to 1050 degrees C to 1120 degrees C (1922 degrees F to 2048 degrees F) and water-quenched immediately to dissolve chromium carbides and restore full corrosion resistance.
• Surface Cleaning & Finishing: Shot blasting with stainless steel cut wire media removes oxide scale, preparing parts for secondary operations or passivation.
Materials and Technical Specifications
We melt and pour a broad spectrum of steel alloys in our medium-frequency induction furnaces. Chemical analysis is confirmed via optical emission spectrometry (OES) prior to tapping.
Standard Material Specifications & Typical Properties
|
Material Group |
Standard / Grade |
Equivalent Grades |
Tensile Strength (MPa) |
Yield Strength (MPa) |
Elongation (%) |
Hardness (HB/HRC) |
Primary Industrial Application |
|
Carbon Steel |
ASTM A27 Grade 65-35 |
GS-45 / 1.0425 |
≥ 450 |
≥ 240 |
≥ 24 |
140 – 180 HB |
General structural brackets, housings |
|
Carbon Steel |
ASTM A216 Grade WCB |
GS-C25 / 1.0619 |
≥ 485 |
≥ 250 |
≥ 22 |
143 – 187 HB |
Valve bodies, pressure equipment, pumps |
|
Low Alloy Steel |
ASTM A148 80-50 |
25CrMo4 / 1.7218 |
≥ 550 |
≥ 345 |
≥ 18 |
170 – 220 HB |
High-stress machinery arms, wear components |
|
Low Alloy Steel |
ASTM A148 105-85 |
42CrMo4 / 1.7225 |
≥ 725 |
≥ 585 |
≥ 17 |
230 – 285 HB |
Mining knuckles, drive gears, structural pivots |
|
High Manganese |
ASTM A128 Grade C |
X120Mn12 / 1.3401 |
≥ 730 |
≥ 350 |
≥ 30 |
~200 HB (Work hardens to >500 HB) |
Crusher liners, excavator teeth, track shoes |
|
Stainless Steel |
ASTM A743 CF8 (304) |
1.4308 / GX5CrNi19-10 |
≥ 485 |
≥ 205 |
≥ 35 |
≤ 200 HB |
Chemical pump casings, marine fittings |
|
Stainless Steel |
ASTM A743 CF8M (316) |
1.4408 / GX5CrNiMo19-11-2 |
≥ 485 |
≥ 205 |
≥ 30 |
≤ 200 HB |
Corrosive process equipment, offshore flanges |
Mechanical Properties (As-Heat-Treated Condition)
|
Property |
Standard Requirement (ASTM A351 CF8M) |
Typical Test Value |
Test Method |
|
Tensile Strength |
>= 485 MPa (70 ksi) |
520 - 620 MPa |
ASTM A370 / EN ISO 6892-1 |
|
Yield Strength (0.2% offset) |
>= 205 MPa (30 ksi) |
240 - 290 MPa |
ASTM A370 / EN ISO 6892-1 |
|
Elongation in 2 in. (50 mm) |
>= 30 % |
40 - 55 % |
ASTM A370 / EN ISO 6892-1 |
|
Hardness |
Not specified |
140 - 180 HBW |
ASTM E10 / ISO 6506-1 |
|
Impact Energy (Charpy V-Notch at 20 degrees C) |
N/A (Optional at -196 degrees C) |
>= 100 J |
ASTM E23 |
Material Standards Cross-Reference
• ASTM / ASME: ASTM A351 / A743 / A744 Grade CF8M; UNS J92900
• EN / DIN Standard: EN 10283 1.4408; GX5CrNiMo19-11-2
• JIS Standard: JIS G5121 SCS14A
• Wrought Equivalent: AISI 316 / UNS S31600 / 1.4401
Key Product Features
Pitting Corrosion Resistance: With PREN >= 23.0 (PREN = %Cr + 3.3x%Mo + 16x%N), the 2.0-3.0% Molybdenum addition protects components in chloride-rich and marine environments.
Intergranular Corrosion Immunity: Solution heat treatment above 1050 degrees C dissolves chromium carbide precipitates at grain boundaries, preventing intergranular attack in acidic media.
Complex Thin-Wall Geometry: The silica sol investment casting process produces wall thicknesses down to 2.5 mm, internal fluid passages, and intricate contour detail without draft angles required by sand casting.
Dimensional Consistency: Near-net shape production limits required machining allowances to 0.5 mm - 1.5 mm on critical functional surfaces, reducing raw material waste and cycle times.
Pressure Containment Integrity: Dense, pore-free casting structure suitable for pressure ratings from PN16 to PN100 (Class 150 to Class 600) under API 600, ASME B16.34, and EN 12516 standards.
Typical Applications
Industrial Valves & Fluid Control: Valve bodies, bonnets, balls, butterfly valve discs, check valve plates, and wedge gates for chemical transport lines.
Pumping Systems: Closed and open impellers, pump volute casings, wear plates, and mechanical seal housings handling saltwater, mild acids, and slurries.
Marine Hardware & Offshore Equipment: Deck fittings, hinges, pipe strainers, thru-hull connections, and winch housings exposed to splash zones.
Food, Beverage & Pharmaceutical Processing: Sanitary valve bodies, pipe fittings, mixing blades, and separator components requiring smooth, easy-to-clean surfaces (Ra < 0.8 um after mechanical polishing).
Chemical & Petrochemical Processing: Heat exchanger nozzles, flowmeter bodies, manifold blocks, and sensor housings operating in acidic or alkaline environments.
Machining and Secondary Operations
To deliver installation-ready components, our in-house machining facility utilizes 10 vertical and horizontal CNC machining centers along with 20+ CNC lathes.
In-House Machining Capabilities
• CNC Milling & Turning: Tolerances down to +/-0.01 mm (+/-0.0004 in) on critical bores, flange faces, and seal grooves.
• Drilling, Reaming & Tapping: Precision-threaded ports including NPT, BSPP, BSPT, and ISO Metric threads.
• Wire EDM: Precision cutting for keyways, narrow slots, and internal profiles.
Surface Finishing Process
Raw Casting (Ra 3.2-6.3 um) -> Shot Blasting -> CNC Machining -> Passivation -> Electropolishing (Ra < 0.4 um)
Surface Options
• Acid Pickling & Passivation: ASTM A967 compliant citric or nitric acid treatment to remove free iron contaminants and optimize the passive chromium-oxide layer.
• Electropolishing: Micro-smoothing technique yielding surface roughness down to Ra 0.2 - 0.4 um for pharmaceutical and high-purity applications.
• Mechanical Mirror Polishing: Hand and automated wheel polishing achieving Grit 240, 320, 400, or 600 mirror finishes for architectural and sanitary hardware.
• Tumbling & Vibratory Deburring: Removes sharp edges and flash on small complex parts.
Quality Control and Inspection
Quality management is structured around our ISO 9001:2015 factory certification. Every melt batch is traceable from raw alloy ingot to final delivery.
Quality Assurance Gateways
• Incoming Alloy Ingot Inspection (OES Chemical Analysis)
• In-Process Shell Integrity & Temperature Monitoring
• Melt Heat Spectrometer Test (Certificate EN 10204 3.1)
• Heat Treatment Verification (Chart Records + Hardness Testing)
• Non-Destructive Testing (PT / UT / RT as required)
• Dimensional CMM Verification & Final Sign-off
Inspection Facilities & Equipment
|
Inspection Category |
Equipment / Method |
Standards Compliance |
Output Documentation |
|
Chemical Analysis |
German OBLF Optical Emission Spectrometer (OES) |
ASTM E415 / ASTM E1086 |
Chemical Analysis Report (EN 10204 3.1) |
|
Mechanical Testing |
Universal Tensile Machine & Charpy Impact Tester |
ASTM A370 / EN ISO 6892-1 |
Tensile & Hardness Test Certificate |
|
Dimensional Control |
Hexagon Coordinate Measuring Machine (CMM), Optical Projector |
ISO 8062-3 / ASME Y14.5 |
CMM Inspection Layout Report |
|
Non-Destructive Testing |
Liquid Penetrant (PT), Radiographic (RT), Ultrasonic (UT), Hydrostatic Pressure Testing |
ASTM E165 / ASTM E446 / EN 10228 |
NDT & Pressure Test Reports |
|
Metallographic Inspection |
Metallurgical Microscope (Up to 1000x) |
ASTM E45 |
Grain size & Ferrite content analysis (5-12% target) |
OEM and Custom Manufacturing
We specialize in full-lifecycle OEM program management, transitioning customer concepts into optimized lost foam cast components.
Engineering & Tooling Workflow
• Design for Manufacturability (DFM): Engineering review of customer 3D models using MagmaSoft / AnyCasting solidification modeling to predict hot spots, shrinkage, and gas entrapment.
• Tooling Design & CNC Fabrication: High-precision aluminum pattern tooling milled directly from aviation-grade aluminum (6061-T6) blocks. Tool life: 100,000+ injections.
• Rapid Prototyping: For low-volume validation or pre-production testing, foam patterns can be 5-axis CNC machined directly from solid EPS blocks without building tool steel-cutting prototype lead times to 2–3 weeks.
• PPAP Level 3 Submission: Full Production Part Approval Process submission including Dimensional Layout, Control Plan, FMEA, Material Certs, and Process Capability (Cpk≥1.33).
OEM and Custom Manufacturing
We specialize in custom contract manufacturing based on buyer specifications.
Development Timeline & Workflow
• DFM Review (1-2 Days): Engineering team conducts Design for Manufacturability analysis to optimize draft angles, wall thickness uniformity, and feeding locations.
• Tooling Fabrication (10-15 Days): CNC machining of high-precision aluminum wax injection dies.
• Sample Production & FAI (7-10 Days): Casting, heat treatment, machining, and full dimensional CMM layout inspection.
• Sample Approval: First Article Inspection Report (FAIR) provided alongside 3.1 material certificates and physical sample shipment.
• Mass Production Lead Time: Standard 30-35 days after sample approval.
Production Capacity
• Facility Footprint: 30,000+ square meters
• Workforce: Around 180 skilled technicians and engineers
• Annual Output: 2,500 Metric Tons of high-precision investment castings
What Buyers Should Provide for an RFQ
To receive an accurate technical proposal and commercial quote within 24 to 48 hours, please include the following details in your inquiry:
2D & 3D Drawings:
• 3D Files: STEP (.stp), IGES (.igs), or SolidWorks (.sldprt) for volume calculations.
• 2D Files: PDF or DWG/DXF with explicit dimensional tolerances, thread specifications, and geometric tolerances (GD&T).
• Material Standard & Grade: Specify ASTM A351 CF8M, EN 10283 1.4408, or custom chemical limits.
• Quantity & Order Frequency: Estimated First Order Quantity (FOQ) and Annual Usage Quantity (EAU).
• Machining Requirements: Indicate whether parts are needed As-Cast, Partially Machined, or Fully CNC Machined to final drawing tolerances.
Quality & Testing Requirements:
• Specific NDT requirements (e.g., 100% Dye Penetrant, Radiography per Level 2 ASTM E446).
• Hydrostatic or air-under-water pressure test parameters (e.g., 20 bar for 60 seconds).
• Required certification (e.g., EN 10204 3.1, 3.2, or specific marine classification society witness tests).
Surface Treatment: Specify pickling, electropolishing, mechanical polishing grade, or shot blast finish.
Frequently Asked Questions
Q: What is the main operational difference between CF8M cast steel and 316 wrought stainless steel?
A: CF8M is chemically formulated to match AISI 316 performance in a cast state. To achieve adequate weldability and prevent hot tearing during solidification, CF8M typically contains 5% to 12% delta ferrite in its microstructure, whereas wrought 316 is fully austenitic. Mechanical strength and corrosion resistance are functionally equivalent when CF8M undergoes full solution annealing.
Q: Why is solution annealing mandatory for CF8M castings?
A: During slow cooling after casting, chromium carbides precipitate at the grain boundaries between 425 degrees C and 860 degrees C, depleting adjacent areas of chromium (sensitization) and rendering the steel vulnerable to intergranular corrosion. Solution annealing at 1050 degrees C to 1120 degrees C re-dissolves these carbides into the austenitic matrix, and rapid water quenching prevents them from re-precipitating.
Q: How does CF8M compare to CF3M (316L equivalent)?
A: CF8M has a maximum carbon content of 0.08%, while CF3M limits carbon to 0.03% max. If the cast part requires post-casting welding without subsequent solution heat treatment, CF3M is recommended to avoid carbide precipitation in the heat-affected zone (HAZ). For applications operating at standard temperatures where parts are fully heat-treated by us prior to delivery, CF8M offers slightly higher yield strength.
Q: What linear tolerances can your silica sol casting process achieve without machining?
A: We maintain casting tolerances according to ISO 8062-3 Grade CT4 to CT6. For dimensions under 50 mm, typical linear tolerance is +/-0.3 mm to +/-0.5 mm. Features requiring tighter limits (e.g., ISO fit H7/f7, thread profiles, bearing seats, or flat sealing faces) are completed during secondary CNC machining.
Q: Can Wabon supply EN 10204 3.1 material certificates with full heat traceability?
A: Yes. Every production batch includes an official EN 10204 3.1 Inspection Certificate detailing exact heat numbers, chemical composition verified by optical emission spectrometry, physical tensile test data, hardness values, and heat treatment log records.
