Handbook on stainless steels, duplex and nickel alloys.

In engineering and manufacturing, selecting the right materials is critical, especially in corrosive environments. This decision can determine whether a product will remain in good condition for decades or deteriorate in a short time. But which materials excel in extreme conditions? To answer this question, we must explore the history and properties of three major players: stainless steels, duplex stainless steels and nickel alloys.

In 1913, Harry Brearley, a British engineer, created the first stainless steel by combining iron, chromium and carbon. This alloy was noted for its exceptional resistance to corrosion, thanks to a protective layer of chromium oxide that prevents damage from reaching the interior of the material. This made it an ideal choice for applications in demanding environments such as the marine, chemical and food sectors.

There are different varieties of stainless steel, with specific properties. These include austenitic stainless steels, which are known for their excellent corrosion resistance and ease of handling. Over time, this material has been essential in fields such as shipbuilding and the food industry, establishing itself as a versatile and essential resource for modern engineering.

Despite the qualities of traditional stainless steels, even more robust materials were sought for particularly aggressive environments. This is how duplex steels emerged, such as alloy W. 1.4462 UNS S31803, which represent a significant evolution. These materials combine the advantages of austenitic and ferritic steels, offering better mechanical strength, greater tolerance to high temperatures and greater protection against corrosion.
Although introduced in the 1930s, their use has become popular in recent years in sectors such as chemicals, oil and offshore.

Duplex steel variants, such as super duplex (e.g. W. 1.4410 UNS S32750 and W. 1.4501 UNS S32760), exhibit outstanding performance under extreme conditions. These materials are ideal for components such as pipes, valves and pumps designed to withstand highly corrosive environments.

In scenarios where even stainless and duplex steels may not be sufficient, nickel alloys are positioned as the most resistant option. Materials such as INCONEL® 625, INCONEL® 718, HASTELLOY® C276 and INCOLOY® 825 are recognized for their high resistance to both corrosion and extreme temperatures.

Their development, initiated at the end of the 19th century, was consolidated in the 20th century, being widely used in industries such as aerospace and power generation. These alloys excel at maintaining their structural integrity in highly hostile environments, such as gas turbines, nuclear reactors and offshore platforms. The combination of nickel with elements such as chromium and molybdenum enhances their resistance to stress corrosion cracking, high-temperature oxidation and intergranular corrosion, making them essential in critical environments.

Each environment presents unique challenges, and choosing the right material is critical to the success of the project. In corrosive environments, factors such as temperature, pressure, mechanical strength and chemical exposure must be considered. Austenitic stainless steels are ideal for moderate conditions, while duplex steels offer better performance in more severe situations. Meanwhile, for applications where high temperatures and extreme corrosion are combined, nickel alloys offer the best solution, guaranteeing a long service life.

Knowledge of materials is key to ensuring sound decisions in extreme environments. Understanding the properties of stainless, duplex and nickel alloy steels enables successful handling of the challenges of corrosive environments. At KEMPCHEN-COMDIFLEX, we provide high-performance materials designed to meet the needs of critical sectors such as oil, chemical and energy, ensuring durability and reliability even under the most demanding conditions.