ASTM A351 CF3 vs. CF3M Stainless Steel Casting

Stainless steel castings are vital components in various industries due to their excellent mechanical properties and superior resistance to corrosion. Among the numerous types of stainless steel grades available, ASTM A351 CF3 and CF3M have gained significant popularity.

Overview of ASTM A351 Stainless Steel Casting

ASTM A351 is a standard specification for austenitic steel castings, covering heat-resistant and corrosion-resistant stainless steel grades. This standard includes multiple grades, such as CF3, CF3M, CF8, and CF8M, which are suitable for different applications based on their unique characteristics.

ASTM A351 CF3 Stainless Steel Casting

ASTM A351 CF3 Stainless Steel Casting

Chemical Composition

CF3 is an austenitic stainless steel grade with low carbon content. Its chemical composition comprises 18-21% chromium, 9-13% nickel, 0.08% maximum carbon, and a balanced iron composition. Other elements like manganese, silicon, and molybdenum are present in small quantities.

Mechanical Properties

CF3 stainless steel exhibits exceptional mechanical properties, including high tensile strength, excellent ductility, and good impact resistance. It has a tensile strength of 70 ksi (485 MPa) and a yield strength of 30 ksi (205 MPa). The elongation and reduction of area values are 30% and 50%, respectively.

Corrosion Resistance

Due to its high chromium and nickel content, CF3 stainless steel has excellent corrosion resistance. It can withstand various corrosive environments, making it suitable for applications in the chemical, petrochemical, and food processing industries.

ASTM A351 CF3M Stainless Steel Casting

ASTM A351 CF3M Stainless Steel Casting

Chemical Composition

CF3M is a molybdenum-bearing austenitic stainless steel grade with low carbon content. It contains 18-21% chromium, 9-13% nickel, 2-3% molybdenum, and 0.08% maximum carbon. Other elements, such as manganese and silicon, are present in small quantities.

Mechanical Properties

CF3M stainless steel possesses excellent mechanical properties, with a tensile strength of 70 ksi (485 MPa) and a yield strength of 30 ksi (205 MPa). It exhibits an elongation value of 30% and a reduction of area value of 50%, showcasing its outstanding ductility and toughness.

Corrosion Resistance

The addition of molybdenum to CF3M stainless steel further enhances its corrosion resistance. It is highly resistant to pitting, crevice corrosion, and stress corrosion cracking. This makes CF3M suitable for more aggressive environments, such as marine applications and chemical processing plants.

Comparison between ASTM A351 CF3 and CF3M Stainless Steel Casting

Chemical Composition

The primary difference between CF3 and CF3M lies in their chemical compositions. While both grades have low carbon content and similar chromium and nickel percentages, CF3M contains 2-3% molybdenum, which is absent in CF3.

Corrosion Resistance

CF3 and CF3M both exhibit excellent corrosion resistance. However, the addition of molybdenum in CF3M enhances its resistance to pitting, crevice corrosion, and stress corrosion cracking, making it more suitable for aggressive environments.


CF3 is widely used in industries like chemical, petrochemical, and food processing, where corrosion resistance is essential. Typical applications include valve components, pump casings, impellers, and fittings. It is also suitable for cryogenic applications due to its low-temperature strength.

CF3M, on the other hand, is used in more aggressive environments where higher corrosion resistance is required. It is commonly found in marine applications, such as shipbuilding and offshore platforms, as well as in chemical processing plants, pulp and paper mills, and wastewater treatment facilities. The molybdenum content in CF3M also makes it an ideal choice for components exposed to high chloride concentrations, such as desalination plants and swimming pool equipment.


Both CF3 and CF3M stainless steel castings have similar machinability. They can be machined using standard techniques, such as turning, milling, and drilling. However, due to their austenitic structure, they can be prone to work hardening, which may require slower cutting speeds, lubrication, and sharp cutting tools to minimize tool wear and achieve the desired surface finish.


CF3 and CF3M stainless steel castings possess excellent weldability due to their low carbon content. The low carbon content reduces the risk of carbide precipitation, which can lead to intergranular corrosion. Both grades can be welded using conventional welding methods, such as shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), and gas metal arc welding (GMAW). To achieve optimal weld quality, it is crucial to follow proper welding procedures, including preheating, interpass temperature control, and post-weld cleaning.

Selecting the Right Stainless Steel Casting Grade

When choosing between ASTM A351 CF3 and CF3M stainless steel casting, it is essential to consider the specific requirements of the application. Factors to consider include:

  • Corrosion resistance: If the application demands higher corrosion resistance, especially in chloride-rich environments, CF3M would be the better choice due to its molybdenum content.
  • Mechanical properties: Both grades have similar mechanical properties, but if low-temperature strength is required, CF3 might be more suitable.
  • Cost: CF3M may be more expensive than CF3 due to the presence of molybdenum. Depending on the application and budget constraints, this may influence the decision.
  • Availability: It is crucial to check the availability of the desired grade with your casting supplier. Some suppliers may not offer both grades, or one may have a longer lead time than the other.

Why Choose CFS Foundry for CF3 and CF3M Stainless Steel Casting?

CFS Foundry, a leading stainless steel casting foundry in China, specializes in producing CF3 and CF3M stainless steel castings for various industries. With the advanced production equipments and rich casting experience, CFS Foundry has become the top manufacturer of CF3 and CF3M castings in China. By working with CFS Foundry, we have below advantages over other foundries:

Advanced Casting Technologies
CFS Foundry uses state-of-the-art investment casting process to produce high-quality CF3 and CF3M stainless steel castings. Our technical expertise ensures that your components will meet or exceed industry standards.

In-house Machining and Finishing Services
To provide a comprehensive solution for your CF3 and CF3M stainless steel casting needs, CFS Foundry offers in-house machining and finishing services. This allows them to maintain strict quality control, reduce lead times, and deliver finished products that meet your exact specifications.

Quality Assurance
CFS Foundry is committed to ensuring the highest quality for CF3 and CF3M stainless steel castings. We follow rigorous quality control procedures, including dimensional inspection, chemical analysis, and mechanical property testing. This guarantees that your components will meet your expectations and adhere to industry standards.

Experienced Team
CFS Foundry’s team of experienced professionals ensures that your CF8 and CF8M stainless steel casting projects are handled efficiently and effectively. Our technical expertise, combined with a dedication to customer satisfaction, makes us a valuable partner for businesses seeking high-quality stainless steel castings.

Any inquiry on CF3 or CF3M stainless steel casting, pls feel free to contact our foundry by email!

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