When engineers, purchasing staff and valve makers look for corrosion-proof stainless steel castings, CF8M is usually one of the first materials they find.
CF8M is widely used in valve bodies, pump housings, marine equipment, food processing machinery, and chemical industry components. Its combination of corrosion resistance, mechanical strength, and castability makes it one of the most popular stainless steel casting materials worldwide.
But what exactly is CF8M? Is it the same as 316 stainless steel? How does it compare with CF8 and CF3M? And why do so many investment casting manufacturers recommend it for harsh operating environments?
This guide explains everything you need to know about ASTM A351 CF8M stainless steel castings, including material properties, standards, applications, and real-world casting examples.
What Is CF8M Material?
CF8M is a cast austenitic stainless steel grade specified under ASTM A351, a standard covering stainless steel castings for pressure-containing parts.
The designation CF8M can be broken down as follows:
- C = Corrosion-resistant alloy
- F = Iron-Chromium-Nickel alloy family
- 8 = Approximately 18% chromium content
- M = Molybdenum added
The addition of molybdenum significantly improves resistance to chloride attack, pitting corrosion, and chemical corrosion.
Because of this, CF8M is often selected for environments involving:
- Saltwater
- Chemical processing fluids
- Acidic media
- Offshore equipment
- Food-grade applications
In practical terms, CF8M is generally considered the cast equivalent of 316 stainless steel.
Understanding ASTM A351 CF8M
When specifying stainless steel castings for valves, pumps, flanges, and pressure-containing equipment, engineers often encounter the designation ASTM A351 CF8M.
To fully understand the material, it is important to understand both the ASTM A351 standard and the CF8M grade designation.
What Is ASTM?
ASTM stands for the American Society for Testing and Materials, now officially known as ASTM International.
Founded in 1898, ASTM is one of the world’s most recognized standards development organizations. It publishes thousands of technical standards covering materials, manufacturing processes, testing methods, and product performance requirements.
Today, ASTM standards are used globally by:
- Mechanical engineers
- Equipment manufacturers
- EPC contractors
- Oil and gas companies
- Chemical processing plants
- Marine equipment suppliers
- Government agencies
ASTM standards help ensure that materials manufactured by different suppliers meet consistent quality and performance requirements.
For example, when a valve specification requires ASTM A351 CF 8M, buyers can expect the casting to meet defined requirements for:
- Chemical composition
- Mechanical properties
- Heat treatment
- Manufacturing quality
- Testing and inspection
This standardization reduces risk during sourcing and improves interchangeability across global supply chains.
What Is ASTM A351?
ASTM A351 is a material specification covering:
“Castings, Austenitic, Austenitic-Ferritic (Duplex), for Pressure-Containing Parts.”
In simple terms, ASTM A351 defines the requirements for stainless steel castings used in components that must withstand pressure during service.
Typical products covered by ASTM A351 include:
- Valve bodies
- Valve bonnets
- Pump casings
- Impellers
- Pipe fittings
- Flanges
- Pressure vessel components
The standard establishes requirements for:
Chemical Composition
Each stainless steel grade must contain specific amounts of alloying elements such as:
- Chromium
- Nickel
- Molybdenum
- Carbon
- Silicon
- Manganese
These elements directly influence corrosion resistance and mechanical performance.
Mechanical Properties
ASTM A351 also specifies minimum values for:
- Tensile strength
- Yield strength
- Elongation
These requirements ensure castings can safely operate under pressure and mechanical loading.
Heat Treatment
Most ASTM A351 stainless steel castings require solution heat treatment to achieve optimal corrosion resistance and mechanical properties.
Inspection Requirements
Manufacturers may perform:
- Visual inspection
- Dimensional inspection
- Chemical analysis
- Mechanical testing
- Non-destructive testing
These procedures help verify compliance with project specifications.
Typical Chemical Composition of ASTM A351 CF8M
| Element | Content (%) |
| Carbon | ≤ 0.08 |
| Chromium | 18.0 – 21.0 |
| Nickel | 9.0 – 12.0 |
| Molybdenum | 2.0 – 3.0 |
| Manganese | ≤ 1.5 |
| Silicon | ≤ 2.0 |
| Phosphorus | ≤ 0.04 |
| Sulfur | ≤ 0.04 |
| Iron | Balance |
The combination of chromium and molybdenum creates a protective passive layer that helps prevent corrosion in demanding environments.
Is CF8M Equivalent to 316 Stainless Steel?
The short answer is yes.
CF8M is generally recognized as the casting equivalent of wrought 316 stainless steel.
Material Equivalency
| Cast Grade | Wrought Grade |
| CF8 | 304 Stainless Steel |
| CF8M | 316 Stainless Steel |
| CF3M | 316L Stainless Steel |
Although CF8M and 316 share similar chemistry, they are manufactured differently.
CF 8M (Cast)
- Produced through casting processes
- Ideal for complex shapes
- Excellent for valve and pump bodies
316 Stainless Steel (Wrought)
- Produced by rolling or forging
- Better for plate, bar, and tubing products
- Often used for fabricated assemblies
Both materials provide similar corrosion resistance and service performance.
Mechanical Properties of CF 8M
The mechanical properties of CF8M make it suitable for pressure-bearing industrial equipment.
| Property | Typical Value |
| Tensile Strength | ≥ 485 MPa |
| Yield Strength | ≥ 205 MPa |
| Elongation | ≥ 30% |
| Hardness | Approx. 150–190 HB |
These values allow CF8M castings to withstand:
- High-pressure systems
- Dynamic loading
- Moderate impact conditions
- Long-term industrial service
Corrosion Resistance of CF8M
One of the biggest reasons engineers select CF8M material is its excellent corrosion resistance.
Resistance to General Corrosion
The chromium content forms a passive oxide film that protects the metal surface.
Resistance to Chlorides
Molybdenum improves resistance to:
- Pitting corrosion
- Crevice corrosion
- Saltwater attack
This makes CF8M superior to CF8 in marine and coastal environments.
Chemical Resistance
CF8M performs well in contact with:
- Organic acids
- Food processing chemicals
- Water treatment chemicals
- Petrochemical fluids
For aggressive chemical environments, CF8M often delivers significantly longer service life than standard stainless steel grades.
CF 8M vs CF 8: What Is the Difference?
Many buyers compareCF8 and CF8M before placing casting orders.
Comparison Table
| Property | CF8 | CF8M |
| Equivalent Grade | 304 | 316 |
| Molybdenum | No | Yes |
| Corrosion Resistance | Good | Excellent |
| Chloride Resistance | Moderate | High |
| Marine Service | Limited | Excellent |
| Material Cost | Lower | Higher |
When to Choose CF8
Choose CF8 when:
- Corrosion conditions are mild
- Cost is the primary concern
- No chloride exposure exists
Typical castings include:
- Water pump bodies
- General machinery components
- Industrial fittings
When to Choose CF8M
Choose CF8M when:
- Chlorides are present
- Saltwater exposure exists
- Chemical corrosion is expected
- Long service life is critical
Typical castings include:
- Valve bodies
- Marine hardware
- Chemical pump housings
- Offshore equipment
CF8M vs CF3M: What Is the Difference?
CF3M is another popular stainless steel casting material.
Comparison Table
| Property | CF8M | CF3M |
| Carbon Content | ≤ 0.08% | ≤ 0.03% |
| Equivalent Grade | 316 | 316L |
| Weldability | Good | Better |
| Intergranular Corrosion Resistance | Good | Excellent |
| Cost | Lower | Slightly Higher |
Advantages of CF3M
The lower carbon content reduces carbide precipitation during welding.
As a result, CF3M is often preferred for:
- Welded structures
- Pharmaceutical equipment
- Food processing systems
- Highly corrosive chemical environments
Typical CF3M castings include:
- Sanitary valves
- Pharmaceutical pump components
- Food-grade processing equipment
Common Applications of CF 8M Castings
CF8M stainless steel castings are used across many industries.
Valve Castings
Common products include:
- Ball valve bodies
- Gate valve bodies
- Check valves
- Butterfly valve components
Pump Components
Examples include:
- Pump casings
- Impellers
- Diffusers
- Wear rings
Marine Equipment
CF8M performs well in seawater and offshore environments.
Typical components include:
- Deck fittings
- Marine pumps
- Offshore platform hardware
Food Processing Equipment
Its corrosion resistance and cleanliness make it suitable for:
- Mixing equipment
- Sanitary pumps
- Processing machinery
Chemical Processing Industry
Common applications include:
- Chemical transfer pumps
- Reactor accessories
- Flow control valves
Why CF8M Is Ideal for Investment Casting
CF8M is one of the most widely used materials in investment casting.
Excellent Castability
The alloy fills complex mold cavities effectively.
High Dimensional Accuracy
Investment casting produces near-net-shape parts that reduce machining costs.
Superior Surface Finish
The process creates smooth surfaces that improve appearance and functionality.
Long Service Life
The combination of strength and corrosion resistance reduces maintenance requirements.
For these reasons, CF8M investment castings are commonly used in critical industrial applications worldwide.
How to Identify High-Quality CF8M Castings
When sourcing CF8M castings, buyers should verify:
Material Certification
Review chemical composition reports.
Spectrometer Testing
Confirm alloy chemistry matches ASTM requirements.
Heat Treatment Records
Verify proper solution treatment procedures.
Dimensional Inspection
Check critical dimensions and tolerances.
Non-Destructive Testing
Recommended methods include:
- PT (Dye Penetrant Testing)
- RT (Radiographic Testing)
- UT (Ultrasonic Testing)
These inspections help ensure reliable performance in service.
JC Casting Success Story: CF 8M Valve Body Project
A European valve manufacturer approached JC Casting seeking a corrosion-resistant solution for chemical processing equipment.
The customer’s previous supplier experienced recurring issues with surface defects and inconsistent dimensional accuracy.
JC Casting recommended ASTM A351 CF8M investment castings and implemented:
- Strict material chemistry control
- Spectrometer verification
- Solution heat treatment
- 100% dimensional inspection
- PT testing on critical surfaces
The project resulted in:
- Improved casting consistency
- Reduced machining allowance
- Longer service life in chloride-containing environments
- Lower total procurement cost
Today, the customer continues to use CF8M valve body castings supplied by JC Casting for demanding industrial applications.
CF8M material is one of the most important stainless steel casting grades used in modern industry.
As the cast equivalent of 316 stainless steel, ASTM A351 CF8M offers:
- Excellent corrosion resistance
- Strong mechanical properties
- Superior chloride resistance
- Good castability
- Long service life
Compared with CF8, CF8M provides significantly better protection in marine and chemical environments. Compared with CF3M, it offers a balance between performance and cost for many industrial applications.
No matter you’re making valves, pumps, marine gear or chemical processing equipment, CF8M is always a top reliable pick for stainless steel investment castings. At JC Casting, we specialize in precision casting of both CF8 and CF8M materials.Feel free to reach out anytime! We’re here to support your procurement and production requirements.