CD3MWCuN ( 6A, J93380 ) Super Duplex Stainless Steel


CD3MWCuN duplex stainless-steel overview

CD3MWCuN is a high performance duplex stainless steel with excellent corrosion resistance and high strength. Composed of austenitic and ferritic phases, it has a unique combination of mechanical and corrosion properties suitable for a wide range of applications including offshore oil rigs, chemical processing facilities and desalination plants.
CD3MWCuN, also known as UNS S32760, contains about 25% chromium, 7% nickel, 3% molybdenum and copper. More resistant to corrosion than SS2205 (CD3MN), these elements provide excellent resistance to general, pitting and crevice corrosion and stress corrosion cracking even in corrosive and high temperature environments.
In addition, A890/A995 Gr 6A has excellent toughness and formability for complex shapes and structures. It can be welded, machined and fabricated using standard methods and has good thermal and electrical conductivity.
Overall, It is a highly versatile and reliable duplex stainless steel that offers excellent corrosion resistance, strength and durability in challenging environments

Advantages and disadvantages of CD3MWCuN

A995 6A(J93380,CD3MWCuN) is a specific grade of duplex stainless steel that contains a higher copper content compared to other duplex grades. It offers unique advantages and disadvantages. Let’s explore them:


  • Corrosion Resistance: Gr 6A exhibits excellent resistance to corrosion, particularly in environments containing chlorides, sulfuric acid, and seawater. Its high copper content enhances its resistance to localized corrosion and pitting, making it suitable for marine and offshore applications.
  • High Strength: This grade provides high tensile and yield strength, offering structural integrity and durability to components subjected to heavy loads and stress.
  • Improved Weldability: It demonstrates good weldability, allowing for easy fabrication and assembly of complex structures without compromising the material’s integrity. Its copper content aids in reducing the risk of hot cracking during welding.
  • Enhanced Thermal Conductivity: The presence of copper in it improves its thermal conductivity compared to standard duplex grades. This property is advantageous in applications where heat transfer is critical, such as heat exchangers and thermal management systems.


  • Cost: Due to its higher copper content, It can be more expensive compared to other duplex stainless-steel grades, which may impact its selection for cost-sensitive applications.
  • Sensitivity to Heat Treatment: J933380 requires careful control during heat treatment processes to avoid the formation of detrimental phases and maintain the desired mechanical properties.
  • Limited Availability: CD3MWCuN may not be as widely available as other duplex stainless steel grades, making it less accessible for certain projects and applications.
  • Copper-Related Challenges: While copper enhances certain properties, it can also present challenges, such as increased susceptibility to stress corrosion cracking under specific conditions.
  • When considering CD3MWCuN for a specific application, it is essential to evaluate its advantages and disadvantages against the project requirements, budget constraints, and environmental conditions. Proper material selection, fabrication techniques, and adherence to recommended practices will ensure the optimal performance and longevity of CD3MWCuN components.

25Cr-7Ni-Mo-N(A890 Gr 6A) Chemical Composition and Mechanical Properties

Chemical Composition

Carbon:                                                                  0.03% Max

Manganese:                                                          1.00% Max

Silicon:                                                                   1.00% Max

Phosphorus:                                                          0.03% Max

Sulfur:                                                                   0.025% Max

Chromium:                                                        24.00-26.00%

Nickel:                                                                 6.50 – 8.50%

Molybdenum:                                                   3.00 – 4.00%

Nitrogen:                                                             0.20 – 0.30%

Tungsten:                                                            0.50-1.00%

Copper:                                                             0.50-1.00%

Pulp and Paper Industry

Mechanical Properties

Application of CD3MWCuN in oil platform
  • Yield Strength:                        65 ksi Min
  • Tensile Strength:                    100 ksi
  • Elongation at 2 in:                  25% Min

CD3MWCuN Reference Casting Standards and others

CD3MWCuN material equivalent to

ASTM A351 Grade CD3MWCuN;ASTM A890 Grade 6A; Type 25Cr-7NiMo-N;Casting UNS J93380; ACI CD3MWCuN;SA995 6a ASTM A789/ASTM A790/ASTM A276: Wrought UNS S32760; ASTM A182 F55

The Casting Typical Application

  • A995 6A (also known as 5A or ASTM A890 Grade 6A) is a duplex stainless steel casting material that offers excellent strength, corrosion resistance, and thermal conductivity. It finds application in various industries where these properties are highly desirable. Some typical applications of CD3MWCuN casting include:
  • Oil and Gas Industry: It is extensively used in offshore oil and gas platforms, subsea equipment, and processing facilities. Its exceptional corrosion resistance and high strength make it suitable for withstanding harsh environments, corrosive media, and high-pressure conditions encountered in oil and gas exploration and production.
  • Chemical Processing: It is commonly employed in chemical processing plants where resistance to corrosive chemicals, acids, and high temperatures is essential. It is utilized in components such as pumps, valves, heat exchangers, and reactor vessels, ensuring reliable and long-lasting performance in aggressive chemical environments.
  • Power Generation: It finds application in power generation facilities, including thermal power plants and nuclear power plants. It is used in turbine components, valves, and piping systems that meet high-temperature steam, corrosive cooling water, and other aggressive media.
  • Desalination Plants: It is suitable for desalination plants, particularly in components exposed to seawater, such as pumps, valves, and heat exchangers. Its corrosion resistance and thermal conductivity contribute to efficient and reliable operation in the desalination process.
  • Pulp and Paper Industry: It is utilized in the pulp and paper industry, particularly in bleach plant equipment, digesters, and chemical processing units. Its corrosion resistance, strength, and thermal conductivity make it suitable for handling corrosive chemicals and withstanding high-temperature processes.
  • Marine and Coastal Applications: It is commonly used in marine and coastal structures, such as offshore platforms, seawater intake systems, and coastal infrastructure. Its resistance to corrosion in saltwater, excellent strength, and thermal conductivity make it ideal for demanding marine environments.
  • These are just a few examples of the typical applications of casting. Its unique combination of properties makes it a preferred choice in industries where strength, corrosion resistance, and thermal conductivity are critical for reliable and efficient performance.

CD3MWCuN Casting Heat treatment process

The heat treatment process for CD3MWCuN (ASTM A890 Grade 6A) casting is an essential step in optimizing its mechanical properties and ensuring its performance in various applications. The recommended heat treatment process for casting typically involves the following steps:

  1. Solution Annealing: The casting is heated to a temperature range of 1040°C to 1120°C (1900°F to 2050°F) and held at this temperature for a specific duration to dissolve any precipitates and promote homogeneity within the material’s microstructure. The soaking time can vary depending on the casting size and thickness.
  2. Water Quenching: After the solution annealing process, the casting is rapidly cooled by immersing it in water or a suitable quenching medium. Water quenching helps to achieve the desired mechanical properties and enhance the corrosion resistance of the material. The cooling rate should be controlled to prevent the formation of detrimental phases and ensure the desired microstructure.

It is crucial to follow the recommended guidelines and specifications provided by the material manufacturer or relevant standards for the heat treatment process. The exact parameters, including temperature, duration, and cooling methods, may vary depending on the specific requirements of the application and the casting design.

Proper heat treatment ensures the desired microstructure, mechanical properties, and corrosion resistance of CD3MWCuN casting, contributing to its optimal performance and longevity in demanding environments. It is advisable to consult with experts and professionals in the field to ensure the appropriate heat treatment process is applied for specific applications and to achieve the desired material properties.