CD4MCUN duplex stainless steel


CD4MCUN duplex stainless steel overview

CD4MCuN is an alloy made of iron, chromium, nickel, copper, and molybdenum. It has superior resistance to corrosion in many different environments than CF8 and CF8M alloys and also offers a higher yield strength of up to twice as much. ASTM A890 CD4MCUN castings are a great choice for tough conditions. You get the benefit of good ductility and high hardness, enabling them to resist abrasions and erosions alike. The alloy exhibits notable resistance to stress corrosion cracking when encountered with chloride-containing solutions or steam. This can be advantageous as it reduces oxidation and consequently minimizes corrosion.

The characteristics of ASTM A890 grade 1b

  • Duplex stainless steel Cd4mcun is an austenitic-ferritic stainless steel alloy. It has an excellent balance of strength, corrosion resistance, and weldability, making it suitable for a variety of applications.
  • The alloy offers a high level of resistance to pitting, crevice corrosion, and stress corrosion cracking. It is more resistant to general corrosion than traditional austenitic stainless steel. It is also highly resistant to chloride-ion stress corrosion cracking. The alloy’s high chromium content provides outstanding corrosion resistance.
  • The alloy has a high yield strength, making it suitable for applications where strength is desired. It also has good cold formability making it suitable for applications such as pipe, fittings, and valves. It is also suitable for use in both cryogenic and high-temperature applications.
  • It also has good weldability, allowing it to be welded with the most common welding techniques. It is important to note that post-weld heat treatment is needed to reduce the risk of cracking. It is also important to use a suitable filler metal when welding this alloy.

CD4MCUN chemical composition

Physical Properties

  • Carbon:                                   0.04% Max
  • Manganese:                           1.00% Max
  • Silicon:                                     1.00% Max
  • Phosphorus:                           0.04% Max
  • Sulfur:                                       0.04% Max
  • Chromium:                            24.5 – 26.5%
  • Nickel:                                     4.7 – 6.0%
  • Molybdenum:                        1.7 – 2.3%
  • Copper:                                       2.7-3.3%
  • N:                                                 0.1-0.25%
  • Yield Strength:                       70 ksi Min
  • Tensile Strength:                 100 ksi Min
  • Elongation at 2 in:                    16% Min

Casting standards


For reference, this list includes a range of casting and corrosive materials commonly used in various industries. It is not an exhaustive list and should not be considered an automatic recommendation of alloy choice in all situations.


  • Industries: Soap Manufacturing, Power Plant, Chemical Processing, Municipal Water Supply, Pulp and Paper, Naval, Petroleum Refining, Paint, Marine, and Textile.


  • Castings: Safety valves, compressor cylinders, feed screws, digester valves, liners, impellers, runway light fixtures (aircraft carriers, airports), seal rings (centrifugal pumps), pump casings, and valve parts.


  • Corrosives: An intensely saline solution, fatty acids, drinking water, boiling fruit juices, seawater, vapor, sulfuric acid of between 15-30% at a temperature of 140-160°F (60-71°C), sulfuric acid at 35-40% and 5% organics, when heated to 185°F (85°C), plus titanium dioxide and titanium sulfate in an acid-based mixture.

Cd4mcun material equivalent

ASTM A890 Grade 1B; ASTM A995 Grade Cd4mcun or 1B; ASME SA351/995 Grade 1B;UNS 32550;Ferraliun 225;J93372;en 10088-x2crnimocun25-6-3

CD4MCuN duplex stainless steel balls
CD4MCuN duplex stainless steel ball of centrifugal casting

Heat Treatment Requirements:

Castings must be heated to Table 1 temperature ranges for maximum corrosion resistance, and complete dissolution of carbides. Quench the casting near the upper end of the temperature range to prevent cracking. The time needed to reach the solution temperature will vary depending on the thickness of the casted sections; it needs to be long enough to ensure that all areas are heated uniformly. Table 1 shows optimal temperatures for completely dissolving carbides and intermetallic precipitates. Table 1’s lower hold temperatures do not improve processing capability or characteristics.