The Densities of Stainless Steels and their Effects on Properties and Applications

The current economy is heavily dependent on industries, and they require different durable materials to manufacture goods. Stainless steel is one such material. It is an iron alloy with chromium, nickel, and other elements and is corrosion-resistant and sturdy.

Knowing the different physical properties of materials is essential in engineering and material science, and one such property is density.

Definition and Calculation of Density in Stainless Steel.

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Density tells you how much matter of a substance is present in a given space or volume.  You can calculate it by dividing its mass by the volume it occupies, expressing your answers in density’s units of g/cm³ or kg/m³. This property can affect a substance’s structure, composition, and physical properties. 

Knowing your material’s density is essential for several reasons. For instance, you must determine your substance’s weight and volume to help in the design and fabrication process. Denser materials are also generally more durable and resist corrosive forces. 

Different materials have different densities. Stainless steel’s density depends upon the steel grade, type, and chemical composition. Generally, it is around 7.5 to 8.0 grams per cubic centimeter.

Contrast this with aluminum, whose density is just 2.70 g/cm³. Lead is much heavier than stainless steel, with a density of 11.34 g/cm³.

You can calculate the density of your stainless steel by dividing its mass by volume. If you have an even sheet, you can measure its volume using a ruler or vernier caliper to determine its length, breadth, and height. Multiplying all these dimensions will give you the volume.

If the steel piece is of an irregular shape, you can use the water displacement method to determine its density. 

Fill a container to the brim with a known volume of water, and put your stainless steel piece in it. It will cause some water to splash out. Take the steel out and measure the water’s volume again. The difference in the initial and final liquid volume is your steel object’s volume. 

You can calculate the mass by weighing the steel on balance. Divide it by the volume to calculate density. 

Factors Affecting the Density of Stainless Steel

Stainless steel density is not a constant value for all stainless steel pieces. Several factors affect the density of stainless steel, such as:

stainless Steel

1.Stainless Steel Composition

Stainless steel is composed of different elements, and all have varying densities. If you use elements with a higher density in alloying steel, your steel will be denser, and vice versa. 

Stainless steel alloys of heavier metals like nickel or molybdenum will be denser, while steel containing aluminum or titanium will be less dense. This is because nickel or molybdenum has a bigger atomic size than aluminum.

The total proportion of a particular metal will also impact the density. For example, stainless steel containing 20% chromium will be denser than stainless steel containing 15%. 

2.Manufacturing Process

The manufacturing processes for stainless steel impact the porosity and grain structure of the steel. Porous steel will be less dense. Grain structure affects the packing density of atoms in the steel. 

Smaller grains have a higher packing density than larger grains as they leave less space between them. If grains are misaligned, which can happen if there is uneven cooling in the manufacturing, the density will be decreased. 

3.Temperature and Pressure Changes.

Variables like temperature and pressure affect the density of materials.

When the temperature increases, the particles in stainless steel vibrate and move further apart from each other. This results in a reduced density. If the temperature decreases, they are packed close to each other, increasing density.

Similarly, the particles are forced close together by applying pressure, increasing the material’s density. Reducing pressure gives them room to move apart, reducing density. 

Comparing Densities Among Different Types of Stainless Steel.

Let’s look at the main stainless steel types and how their density compares.

  1. Austenitic stainless steel. This is the most common type of stainless steel, featuring  non-magnetism and high corrosion resistance. It’s high in nickel, and as nickel is a dense metal, austenitic steel has the highest stainless steel density at 7.9 g/cm³.
  2. Ferritic stainless steel is a magnetic, cost-effective alloy with low carbon content. It does not contain very dense materials and has a density of 7.7 g/cm³.
  3. Martensitic stainless steel has higher carbon content, making it hard, rigid, and brittle. Its density is 7.7 g/cm³.
  4. Duplex stainless steel is a hybrid of austenitic and ferritic stainless steel. As a result, its density is in the middle of the two types at 7.8 g/cm³.

The Effects of Density on Stainless Steel’s Properties.

Density can impact other physical and mechanical properties of stainless steel. Here is how it affects some common properties:

1.Tensile Strength

A material’s tensile strength is its ability to resist breaking under tension or pulling forces. The higher a substance’s density, the more its tensile strength will be. This is because substances with a higher density have closely packed molecules with solid intramolecular bonds, which do not break easily. 

2.Hardness

Hardness in stainless steel measures the steel’s resistance to deformation. Denser steels are also harder, as the molecules are closely packed. Closely packed molecules resist deformation.

3.Ductility

Ductility, or elasticity, is how much steel can deform under stress without breaking. Steel with low density usually has better elasticity, as molecules packed less closely have more room to move about when you apply deformative force.

4.Corrosion Resistance

Denser materials are generally more resistant to corrosive agents. They have a tightly packed structure, which makes it difficult for corrosive agents to penetrate them. 

The Effect of Density on Applications of Stainless Steel.

Stainless Steel in Aerospace Industry

Some industries prefer high-density stainless steel, while others prefer a lower density. Here’s how dense your steel should be for common industries:

  • Aerospace: You require low-density stainless steel in aerospace. If your plane uses denser materials, flying will take too much fuel. So, we prefer materials with a good weight-to-strength ratio in the aerospace industry.
  • Automotive: Automotives require high-density stainless steel as it has a better impact resistance. Your automotive must withstand high impacts in cases of crashes.
  • Medical: Medical devices usually have a lower density to be more portable and easier to handle. However, instruments like bone saws and dentistry equipment need to be stronger, so they can require materials of higher densities.
  • Construction: You should use high-density stainless steel in bridges or buildings as denser steel is more stable and strong.
  • Food and Beverage processing: You prefer less dense stainless steel in food processing as it is lighter and easier to use.
  • Chemical processing: In chemical processing, you are at risk of corrosive chemical reactions. Use denser steel, as it is more resistant to corrosive agents. 
  • Marine: Use less dense stainless steel in marine systems to be lighter and more fuel-efficient.

Relationship Between Density and Other Fabrication Processes of Stainless Steel

Fabrication of stainless steel refers to making usable products from raw stainless steel sheets. Methods include cutting, machining, forming, and welding – all of these are affected by the material’s density. 

1.Formability

Formability of stainless steel is how easy it is to bend or stamp it to shape it according to your needs. Generally, lower-density stainless steel is more formable, as it is easier to bend due to its less tightly packed molecular structure.

2.Welding

You use stainless steel welding to join different parts together. 

You will find it more challenging to weld high-density stainless steel as it will require a higher temperature to melt it due to its strong intermolecular forces. Materials with low densities are generally easier to melt and weld.

3.Machining

Machining refers to the ease of cutting, drilling, milling, or performing any other machine function on stainless steel. As denser steel is harder and resists deformation, it is less machinable. 

Density and Cost of Stainless Steel

Different stainless steel grades have different densities and costs. 

Denser stainless steel has a higher melting temperature and requires more energy in manufacturing. So, the manufacturing costs are higher for denser stainless steel. You can find lighter stainless steel at cheaper rates than denser stainless steel.

However, density is not the only cost parameter. 

While austenitic stainless steel, the densest steel, is more expensive than lighter ferritic steel, this is not always the case. Duplex steel is the most expensive type, sold at $4 to $8 per pound compared to austenitic steel’s $3 per pound, despite being slightly less dense than austenitic steel. The steel’s alloying agents typically affect cost significantly too.

Effect of Density on the Stainless Steel

Carbon Steel Properties

The environmental impact of stainless steel is generally favorable: it is among the most sustainable materials. You can recycle it up to 90%, so you don’t have to mine as much for its raw materials.

However, density can affect the metal’s carbon footprint. Lighter stainless steel is generally a more eco-friendly material than denser steel. 

The manufacturing process of stainless steel uses massive energy as you have to heat the furnace up to 1500 degrees Celcius to melt the elements. Dense stainless steel uses denser materials like nickel, which have a higher melting point than lighter elements. So, denser steels have higher carbon footprints. Use lighter stainless steel for carbon footprint reduction

Lighter stainless steel is also one of the more recyclable materials. Denser materials require a higher melting temperature and are more complex and costly to recycle.

However, denser stainless steel is durable and lasts long, so you don’t have to produce too much. This factor increases its sustainability.

Conclusion

Stainless steel density is an important parameter that affects other physical properties. The denser a material is, the less formable, machinable, or weldable it will be. However, denser substances are more resistant to deformation and corrosive forces. 

This alloy’s density depends upon its chemical composition, microstructure, and manufacturing process, and variables like temperature and pressure affect it.

Contact us today for a quote for stainless steel of any density!

FAQs

1.Does the density of stainless steel affect its magnetic properties?

Yes, the magnetic properties of stainless steel are related to its density. Denser stainless steel has more magnetic permeability, which is how much you can magnetize a material. This is because the closely packed structure of denser materials has more magnetic domains per unit volume.

2.Can the density of stainless steel be modified after production?

No, you cannot modify the stainless steel density after production. This is because density is related to the chemical composition of stainless steel, and it is impossible to change its chemical composition after its production. However, increasing or decreasing temperature can slightly affect its density.

3.Is a higher density always better for stainless steel?

The density of stainless steel is related to its applications. You prefer higher-density stainless steel for some applications, such as automotive ones, but this is not always the case. For example, the aerospace industry requires lighter stainless steel so that planes can move easily. 

One Stop Stainless Steel Supply.

Whether you need stainless steel materials for your business or fabrication projects, TuoLian is your best supplier. You can find all types, grades, and thicknesses based on your needs. Guaranteed that we provide the best quality at a reasonable cost.
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