Chemical Composition and Microstructure of Low Alloy Duplex Stainless Steel 1Cr21Ni5Ti

Low Alloy Duplex Stainless Steel 1Cr21Ni5Ti

Low alloy duplex stainless steel 1Cr21Ni5Ti is a dual-phase stainless steel with excellent corrosion resistance, strength and hardness. The steel material is a new generation of high-performance steel that has been developed with the advent of new manufacturing techniques, materials and processes. This alloy offers an alternative to conventional austenitic stainless steels that is often used as a material of choice for various industries, such as food processing, automotive, and oil and gas.

Chemical Composition

Low alloy duplex stainless steel 1Cr21Ni5Ti has a slightly lower chromium content than the standard austenitic stainless steel grades. The major alloying elements are a balance of chromium (15.0%-17.0%), nickel (6.0%-8.0%) and titanium (1.5%-3.0%). Other alloying elements that are present include nitrogen (0.06%-0.15%) and molybdenum (0.15%-0.2%). The small amount of molybdenum helps to increase the stability of the alloy and gives a higher resistance to pitting.

Microstructure

The microstructure of low alloy duplex stainless steel 1Cr21Ni5Ti is dependent on the heat-treatment process applied to the alloy. It has a characteristic dual-phase microstructure, consisting of both austenitic and ferritic elements. The structure of 1Cr21Ni5Ti typically has a 60/40 ratio of ferrite to austenite. This dual-phase microstructure provides the alloy with improved corrosion resistance, strength and hardness. The dual-phase microstructure also improves the weldability and formability of the material. As with other stainless steels, the microstructure can be further modified by cold-working or heat-treating the material.

The corrosion resistance of low alloy duplex stainless steel 1Cr21Ni5Ti is significantly higher than that of standard austenitic stainless steel grades. It has excellent resistance to chloride-induced stress corrosion and to stress corrosion cracking. The material is also very resistant to pitting and crevice corrosion. 1Cr21Ni5Ti has excellent resistance to general corrosion in a wide variety of polluted, oxidizing and acidic environments.

Overall, low alloy duplex stainless steel 1Cr21Ni5Ti offers excellent corrosion resistance, strength and hardness in comparison with standard austenitic stainless steel grades. Its dual-phase microstructure provides improved weldability and formability, while its higher chromium, nickel and titanium contents offer improved resistance to corrosion and a greater range of uses.

Austenitic-ferritic duplex stainless steel 1Cr21Ni5Ti is a commonly used dual-phase steel. It belongs to Cr series stainless steel, its chemical composition (%) is as follows:

C: ≤0.06、Si: ≤0.60、Mn: ≤1.20、Cr: 21.0-23.0、Ni: 5.0-7.0、Mo: 2.00-3.00、N: 0.10-0.22、Ti: 0.07-0.12、S: ≤0.015、P: ≤0.030、Cu: ≤0.25、Nb: 0.03-0.20.

It has excellent mechanical properties and corrosion resistance, especially in medium containing a certain concentration of chloride ions, it has excellent pitting resistance and crevice corrosion resistance. The microstructure of 1Cr21Ni5Ti is a combination of austenite and ferrite, showing a mixed structure of austenite and ferrite. The overall morphology of ferrite grains appears as a lath shape, and the austenite grains appear as equiaxed grains. The overall average grain size is 8-10μm. The volume fraction of austenite is greater, and the austenite content is 49.8%, the ferrite content is 50.2%.

1Cr21Ni5Ti has the characteristics of high strength and good toughness, excellent corrosion resistance and weldability. Because of its good comprehensive performance, it is especially suitable for use in chloride-containing media to manufacture pressure vessels, oil and gas pipelines, desalination plants, boats, marine engineering and other industries.