Austenitic-ferritic (duplex) stainless steel S21860 1Cr18Ni11Si4AlTi chemical composition

Introduction

The structure and properties of austenite-ferritic stainless steel S21860 (1Cr18Ni11Si4AlTi) make it a desirable material for use in a variety of industries and applications. This steel is a dual-phase stainless steel, composed mainly of austenite (γ-Fe) and ferrite (α-Fe). This combination of phases provides the steel with highly desirable corrosion and wear resistance characteristics that make it such a sought after material. In addition, the steel exhibits excellent formability and weldability, making it ideal for use in multiple industries.

Structure

The austenite-ferritic stainless steel S21860 (1Cr18Ni11Si4AlTi) is composed of a variety of different alloying elements. The chemical composition of the steel is shown in Table 1. The main components are iron (Fe) and chromium (Cr). Iron is the most abundant element, constituting up to 90.5% of the total composition. Chromium is the second most abundant element, accounting for up to 12.5% of the total composition. Smaller amounts of nickel (Ni), molybdenum (Mo), silicon (Si), aluminum (Al) and titanium (Ti) make up the remainder of the composition.

Table 1. Chemical composition (weight %) of the austenite-ferritic (dual-phase) stainless steel S21860 (1Cr18Ni11Si4AlTi)

Elements Weight %

Fe 90.5

Cr 12.5

Ni 5.8

Mo 0.4

Si 4.1

Al 0.6

Ti 1.2

The combination of these alloys results in a microstructure of austenite and ferrite phases. Austenite is primarily present in grain boundaries and interior portions of grains, while ferrite is present mainly in the grain boundaries. This combination of phases provides the steel with excellent corrosion and wear resistance characteristics. The two phases also give the steel a desirable combination of strength, hardness, and ductility, making it an ideal material for a variety of applications.

Mechanical Properties

The austenite-ferritic stainless steel S21860 (1Cr18Ni11Si4AlTi) has excellent mechanical properties. Due to its dual-phase structure, the steel possesses a combination of strength, hardness, and ductility, making it suitable for use in a variety of applications. The steel has a tensile strength of up to 850 MPa, and a yield strength of up to 595 MPa. It also has a good elongation at break and a Brinell hardness of up to 250.

Corrosion Resistance

Due to the combination of its austenite and ferrite phases, the austenite-ferritic stainless steel S21860 (1Cr18Ni11Si4AlTi) has excellent corrosion resistance characteristics. The chromium content of the steel provides it with good resistance to oxidation, as well as good resistance to stress corrosion cracking. The presence of nickel and molybdenum in the alloy also provide the steel with good resistance to corrosion and pitting in a variety of environments.

Weldability and Formability

The austenite-ferritic stainless steel S21860 (1Cr18Ni11Si4AlTi) is highly weldable and has good formability characteristics. The steel is easy to weld with no special preheating or post-weld treatments required. The steel is also highly formable, making it suitable for use in forming operations, such as bending, forming, and stamping.

Applications

Due to its combination of excellent corrosion resistance, good mechanical properties, and good weldability/formability characteristics, the austenite-ferritic stainless steel S21860 (1Cr18Ni11Si4AlTi) is suitable for use in a variety of applications. The steel is commonly used in chemical processing applications, such as tanks, valves, pipework, and pumps. It is also used in oil and gas applications, such as piping, pressure vessels, and other components. In addition, it is often used in food processing industries, due to its corrosion resistance and safety properties.

Conclusion

The austenite-ferritic stainless steel S21860 (1Cr18Ni11Si4AlTi) is a highly desired material due to its combination of strength, hardness, and ductility. The dual-phase structure provides the steel with excellent corrosion resistance and wear resistance, as well as good weldability and formability characteristics. These properties make it suitable for use in a variety of industries and applications, such as chemical processing, oil and gas, and food processing.

S21860 martensitic stainless steel (1Cr18Ni11Si4AlTi, DIN X2CrNi1811) is a dual phase stainless steel which combines ferrite and austenite phases. In the as-delivered condition, it is mostly in ferrite phase, and when subjected to appropriate heat treatments, it will transform to austenite phase.

It is a Cr-Ni-Si-Al-Ti based iron alloy with excellent corrosion resistance against a wide range of media, including chloride containing media, with excellent formability and good weldability. It offers higher stress-corrosion cracking resistance than 304 stainless steel and has excellent oxidation and pitting resistance at high temperatures. It is especially good for use in environments with oil, gas and petrochemical applications as it performs well in appliactions where other stainless steels may not be suitable.

The mechanical properties of this steel are very good in the annealed state and are further enhanced when put through appropriate heat treatment. Its tensile strength is 930MPa in the annealed condition, with yield strength of 850MPa in the same condition. Its hardness can reach up to HRC36 after hardening.

S21860 martensitic stainless steel has good strength, ductility, formability and weldability, making it suitable for a wide range of applications from wire products to kitchen equipment. It is used in cold forming applications such as castings and other formed products, as well as in medical instruments, shipbuilding and piping applications.