316L Stainless Steel Castings (equivalent to ASTM A743/A743M Grade CF3M and EN 10283 1.4409) are low-carbon austenitic stainless steel components manufactured for high-corrosion environments, pressure-containing systems, and fluid-handling equipment.
The extra-low carbon content (C <= 0.03%) prevents chromium carbide precipitation along grain boundaries during thermal exposure. This microstructural stability eliminates the risk of intergranular corrosion in welded assemblies and elevated-temperature service without requiring post-weld solution heat treatment.
Utilizing a 100% Silica Sol investment casting process (lost-wax method), components achieve tight dimensional repeatability, intricate internal passageways, and superior surface integrity compared to conventional water-glass investment casting or sand casting.
Key Purchasing Metrics
• Standard Equivalent: ASTM A743 / A351 Grade CF3M | EN 10283 1.4409 | UNS J92800
• Manufacturing Process: 100% Silica Sol Investment Casting
• Dimensional Tolerance: ISO 8062-3 CT4 – CT6 (As-Cast)
• As-Cast Surface Roughness: Ra 3.2 µm – Ra 6.3 µm (125–250 µin)
• Unit Weight Range: 0.05 kg to 85.0 kg (0.11 lbs to 187 lbs)
• Quality Standard Compliance: ISO 9001:2015, IATF 16949, PED 2014/68/EU Directive
Manufacturing Process
All components are produced using the full silica sol wax-pattern investment casting method. Process parameters are strictly monitored at each stage to ensure structural density and dimensional repeatability:
Production Workflow: Tooling Design → Wax Pattern Injection → Multi-Layer Shelling → Steam Dewaxing & High-Temp Firing → OES Analysis & Pouring → Knockout & Cleaning → Machining & Inspection → EN 10204 3.1 Certification
|
Process Stage |
Technical Execution Parameters |
Quality Control Checkpoint |
|
Tooling & Wax Pattern |
CNC-machined aluminum tooling; temperature-controlled wax injection (62°C - 65°C). |
100% CMM verification of tooling; visual check for pattern sink marks or flash. |
|
Shell Building |
Multi-layer silica sol binder with zircon flour primary face coat; 5–7 backup layers. |
Constant slurry viscosity control; ambient humidity (55 ± 5%) and drying room monitoring. |
|
Dewaxing & Firing |
High-pressure steam dewaxing autoclave (0.8 - 1.0 MPa); high-temperature firing (1050°C - 1100°C). |
Complete wax removal verification; shell thermal strength inspection. |
|
Melting & Pouring |
Medium-frequency induction melting furnace; argon shielding capability; vacuum degassing. |
Optical Emission Spectrometer (OES) chemical verification per heat prior to tap. |
|
Shakeout & Finishing |
Mechanical shell knockout, high-pressure water blasting, cut-off, and ceramic media shot blasting. |
100% visual inspection for surface inclusions, cold shuts, or shrinkage defects. |
Materials and Technical Specifications
Chemical composition and mechanical properties strictly adhere to ASTM A743, ASTM A351 (Grade CF3M), and EN 10283 standards.
Chemical Composition Limits (wt%)
|
Element |
ASTM A743 CF3M (316L Cast) |
EN 10283 1.4409 |
Typical Foundry Heat Control |
|
Carbon (C) |
<= 0.030% |
<= 0.030% |
0.022 - 0.026% |
|
Chromium (Cr) |
17.00 - 21.00% |
17.50 - 19.50% |
17.80 - 18.50% |
|
Nickel (Ni) |
9.00 - 13.00% |
9.00 - 12.00% |
10.00 - 11.50% |
|
Molybdenum (Mo) |
2.00 - 3.00% |
2.00 - 2.50% |
2.10 - 2.45% |
|
Silicon (Si) |
<= 1.50% |
<= 1.50% |
0.60 - 1.10% |
|
Manganese (Mn) |
<= 1.50% |
<= 1.50% |
0.80 - 1.20% |
|
Phosphorus (P) |
<= 0.040% |
<= 0.035% |
<= 0.028% |
|
Sulfur (S) |
<= 0.040% |
<= 0.025% |
<= 0.015% |
Mechanical Properties (Solution Annealed Condition)
|
Mechanical Property |
ASTM A743 CF3M Minimum |
Typical Test Results |
Test Standard |
|
Tensile Strength (Rm) |
>= 485 MPa (70 ksi) |
540 - 620 MPa |
ASTM E8 / ISO 6892-1 |
|
Yield Strength (Rp0.2) |
>= 205 MPa (30 ksi) |
240 - 290 MPa |
ASTM E8 / ISO 6892-1 |
|
Elongation in 2" (A) |
>= 30.0% |
42.0 - 52.0% |
ASTM E8 / ISO 6892-1 |
|
Reduction of Area (Z) |
Not Specified |
> 50.0% |
ASTM E8 |
|
Hardness (Brinell) |
<= 193 HBW |
140 - 175 HBW |
ASTM E10 / ISO 6506-1 |
|
Charpy V-Notch Impact (+20°C) |
Optional |
>= 80 J |
ASTM E23 / ISO 148-1 |
Standard Heat Treatment Protocol
All castings undergo solution annealing:
• Heating in atmosphere-controlled furnaces to 1040°C - 1120°C (1900°F - 2050°F).
• Soaking for a minimum of 1 hour per inch of maximum wall thickness.
• Rapid water quenching to below 400°C within 30 seconds to redissolve intermetallic sigma phases and maximize corrosion resistance.
Key Product Features
Pitting & Crevice Corrosion Resistance: High Molybdenum concentration (2.0-3.0%) delivers elevated Pitting Resistance Equivalent Number (PREN >= 23-25), protecting parts exposed to chloride solutions, marine splash zones, and organic acids.
Intergranular Stability: Carbon capping at 0.03% maximum suppresses chromium carbide precipitation in the Heat-Affected Zone (HAZ) during structural welding or field assembly.
Complex Geometry Retention: Investment casting maintains intricate internal fluid channels, draft angles down to 0.5°, and uniform wall thicknesses starting at 2.5 mm.
Cryogenic Impact Toughness: The stable face-centered cubic (FCC) austenitic matrix prevents ductile-to-brittle transition down to cryogenic service temperatures (-196°C).
Hygienic Surface Capability: Smooth as-cast surfaces (Ra 3.2 - 6.3 µm) can be mechanically polished or electropolished to Ra <= 0.4 µm for sanitary food and pharmaceutical applications.
Typical Applications
|
Industry |
Typical Components |
Primary Operating Conditions & Needs |
|
Chemical Processing |
Valve bodies, ball valve spheres, pump impellers, manifold blocks, flange fittings. |
Exposure to aggressive acids (sulfuric, nitric, acetic), pressure containment, zero porosity leakage. |
|
Marine & Offshore |
Through-hull fittings, hardware brackets, sea water pump casings, heat exchanger heads. |
Continuous exposure to saltwater splash and submerged marine environments; pitting resistance. |
|
Food & Pharmaceutical |
Sanitary pump housings, valve bodies, mixing paddles, fluid connectors. |
Clean-In-Place (CIP) compatibility, non-contaminating micro-finish, zero surface entrapment. |
|
Water & Wastewater |
High-pressure reverse osmosis pump components, spray nozzles, filter housings. |
High-velocity fluid movement containing dissolved solids and high chloride concentrations. |
Machining and Secondary Operations
We provide single-source production from raw casting through final finish machining:
CNC Machining Capabilities
• Equipment: 3-axis, 4-axis, and 5-axis CNC machining centers, CNC turning centers with live tooling.
• Machining Tolerances: Precision feature tolerances down to ±0.008 mm (±0.0003 in).
• Thread Production: NPT, BSPP, BSPT, Metric, and ACME threads verified via calibrated thread gauges.
Surface Treatment & Finishing
• Passivation: Chemical passivation per ASTM A967 (Citric or Nitric acid options) to rebuild the chromium oxide film.
• Surface Polishing: Mechanical mirror polishing (#400–#800 grid) and Electropolishing (Ra <= 0.38 µm / 15 µin).
• Assembly & Testing: Pressure vessel sub-assembly, seal installation, and pneumatic/hydrostatic leak testing up to 200 bar.
Quality Control and Inspection
Quality control protocols are enforced throughout production. Every production batch is delivered with standard EN 10204 3.1 Inspection Certificates.
Quality Assurance Sequence: Raw Material OES Verification → In-Process Shell & Heat Monitoring → Post-Pour Heat Treatment Records → Final Inspection (CMM / NDT / Hydrotest) → 3.1 MTR Issuance
Inspection Facilities & Equipment
• Chemical Analysis: SPECTROMAXx Optical Emission Spectrometer (OES) analyzing 26 elements per heat code.
• Dimensional Inspection: Hexagon 3D Coordinate Measuring Machine (CMM), optical profile projectors, height gauges.
• Non-Destructive Testing (NDT):
Dye Penetrant Inspection (PT) per ASTM E165.
Radiographic Inspection (RT) per ASTM E192 (upon request).
Hydrostatic and Leak Testing up to 200 bar.
• Mechanical Testing: Computer-controlled universal tensile testing machine, Charpy impact test rig, Brinell/Rockwell hardness testers.
OEM and Custom Manufacturing
We produce custom 316L stainless steel components built to client engineering prints and material specifications:
Supported Design Formats: STEP, IGES, Parasolid (.x_t), DWG, DXF, and PDF.
Rapid Tooling & Sampling: 3D-printed SLA/wax patterns for prototype sampling in 10–14 days without hard tooling investments.
Production Tooling: In-house aluminum die design and manufacturing (21–28 days typical lead time).
Batch Production Flexibility: Scalable production capacity ranging from short runs (100 pcs/year) to high-volume automotive/industrial programs (50,000+ pcs/year).
What Buyers Should Provide for an RFQ
To receive a detailed commercial quotation and manufacturing DFM review within 24 hours, please supply the following details:
2D Engineering Drawings:
PDF format with critical dimensions, tolerances, thread specs, and target surface roughness.
3D CAD Models:
STEP, IGES, or Parasolid files for component volume and casting solidification analysis.
Material Grade Requirements:
Specified standard (e.g., ASTM A743 Grade CF3M or EN 10283 1.4409).
Estimated Quantities:
Initial prototype sample quantity, batch order sizes, and Estimated Annual Usage (EAU).
Secondary Operations:
Desired finishing (as-cast, passivated, mirror-polished) and machining details.
Quality & NDT Specifications:
Certification requirements (EN 10204 3.1) and required non-destructive testing (PT, RT, pressure test).
Frequently Asked Questions
Q: What is the primary operational difference between CF8M (316) and CF3M (316L) castings?
A: CF8M permits carbon content up to 0.08%, whereas CF3M restricts carbon to 0.03% max. The low carbon content in CF3M eliminates chromium carbide precipitation during welding, preserving corrosion resistance in welded joints without requiring post-weld solution annealing.
Q: What linear casting tolerances can be maintained in the as-cast state?
A: Using silica sol investment casting, linear tolerances conform to ISO 8062-3 Grade CT4 to CT6. For a nominal dimension of 50 mm, the as-cast tolerance is ±0.35 mm. Tighter tolerances down to ±0.008 mm are achieved through CNC finish machining.
Q: Are material test certificates supplied with each shipment?
A: Yes. Every shipment includes an EN 10204 3.1 Inspection Certificate detailing heat-specific chemical analysis (OES), mechanical properties (tensile, yield, elongation), heat treatment furnace charts, and CMM inspection reports.
Q: How are internal porosity defects prevented in thick-section castings?
A: We utilize MAGMASOFT / ProCAST solidification modeling during tool design to optimize gating and riser layout. For pressure-critical applications, 100% Radiographic Inspection (RT) per ASTM E192 or Liquid Penetrant Inspection (PT) per ASTM E165 can be specified.
