Chemical Composition of Martensitic Stainless Steel S44090 9Cr18

The chemical composition of Martensitic Stainless Steel S44090 9Cr18

Martensitic stainless steel S44090 (9Cr18) is a commonly used martensitic stainless steel grade. It has a comparatively high carbon content and is used in applications as diverse as cutlery, screws and washers, valve bodies and hand tools. Its chromium content gives it significant corrosion resistance and whilst it can be hardened to give it better resistance to mechanical wear and tear, it is not suitable for creating products where the highest levels of resistance are required (e.g. those used in the most abrasive environments).

The chemical composition of Martensitic Stainless Steel S44090 (9Cr18) is shown below.

Carbon (C) 0.85-0.95%

Manganese (Mn) 1.00%

Phosphorus (P) 0.040%

Sulphur (S) 0.030%

Chromium (Cr) 17.00-19.00%

Molybdenum (Mo) 0.75%

Silicon (Si) 1.00%

Nickel (Ni) 0.50%

Nitrogen (N) 0.20%

This compositions gives the alloy excellent corrosion resistance and good weldability (as long as the right welding equipment and techniques are used). The chromium and molybdenum in particular give it improved resistance to general corrosion, pitting, crevice corrosion, stress corrosion cracking and intergranular corrosion. It has relatively low carbon levels which also improves its weldability and gives it higher ductility than other stainless alloys.

Martensitic Stainless Steel S44090 (9Cr18) is widely used in a variety of different applications where its corrosion resistance, mechanical properties and weldability make it a good choice. These include, automotive components, aircraft and space vehicle components, cutlery, surgical instruments, valves, pumps and bearings, encasements for industrial gears, springs, shearing blades, hand tools and spectacle frames.

In conclusion then Martensitic Stainless Steel S44090 (9Cr18) has a chemical composition which gives it good corrosion resistance and weldability, making it suitable for a wide range of applications. Its relatively low carbon content also makes it easier and less expensive to work with than other stainless steels, whilst maintaining good mechanical properties.

Overview

9Cr18 is a martensitic stainless steel alloy with a high carbon content and high chromium content. It contains nine percent chromium, which gives it superior resistance to staining and rusting. 9Cr18 is often used for applications such as cutlery, surgical instruments, and high-pressure valves.

Composition

The composition of 9Cr18 includes the following elements:

Chromium (Cr): 9.0 - 9.5%

Cobalt (Co): 0.3%

Molybdenum (Mo): 0.3 - 0.8%

Nickel (Ni): 0.6 - 0.9%

Manganese (Mn): 0.6 - 0.9%

Tungsten (W): 0.2 - 0.4%

Silicon (Si): 0.25%

Phosphorus (P): 0.035%

Sulfur (S): 0.030%

The combination of high chromium, high carbon, and moderate amounts of molybdenum and tungsten give this alloy excellent corrosion and wear resistance, strength, and hardness.

Physical Properties

9Cr18 has the following physical properties:

• Density: 7.7 g/cm3

• Melting point: 1430 - 1470°C (2490 - 2680°F)

• Specific heat capacity: 0.5 J/g-K

• Thermal conductivity: 16 W/m-K

• Modulus of elasticity: 180 GPa

• Thermal expansion: 11.6 μm/m-K

• Hardness: HRC55 - 59

Applications

9Cr18 is widely used for applications that require corrosion and wear resistance, strength, and hardness. Such applications include:

• Cutlery

• Surgical instruments

• High-pressure valves

• Knife blades and sheaths

• Measuring tools

• Cutting tools

• Springs and fasteners

• Pump parts

• Gears and shafts

• Jewelry

• Watch cases

• Knives

• Washing machine parts

• Industrial components

Conclusion

9Cr18 is a martensitic stainless steel alloy with excellent corrosion and wear resistance, strength, and hardness. It is widely used for many applications that require these properties, including cutlery, surgical instruments, and high-pressure valves.