304 Vs 316 Stainless Steel

304 Vs 316 Stainless Steel: The Ultimate Guide

Whether to choose 304 stainless steel or 316 stainless steel will depend on a range of factors. This guide explores all fundamental aspects you should know about 304 vs. 316 stainless steel.

What Is Stainless Steel?

Stainless steel is an alloy formed between chromium and iron and other elements like carbon, nickel, manganese, molybdenum and nitrogen. Chromium content in stainless steel must always be 10.5% and above, however, the exact percentage is determined by the grade.

What Is 304 Stainless Steel?

304 stainless steel belongs to the family of austenitic stainless steels and it is one of the commonly used stainless steels. In addition to iron and chromium, about 8% nickel forms part of the 304 stainless steel, giving it the name 18/8 steel. A combination of nickel, carbon, iron and chromium to create an alloy with a variety of properties as desired.

304 stainless steel is the grade mostly used in making cookery tools or pans because of its significant properties. Some of the grades under 304 stainless steel include 304L and 304H with low and high carbon content, respectively.

What Is 304 Stainless Steel
What Is 316 Stainless Steel

What Is 316 Stainless Steel?

316 stainless steel is steel made of about 16 – 18% chromium, 2 – 3% molybdenum, 10 – 14% nickel and low carbon content. Molybdenum of 2 to 3% is responsible for the outstanding corrosion resistance properties in 316 stainless steel grades.

After 304 stainless steel, 316 stainless steel is the second most popular steel used in environments prone to corrosion and impact. 316L stainless steel variant contains a low carbon content and is suitable for applications that are exposed to metal sensitization. 316 stainless steel is the variant with high carbon content and it offers great creep resistance and high thermal stability.

Benefits Of 304 Stainless Steel

Benefits Of 304 Stainless Steel
Benefits Of 304 Stainless Steel

Durability

Generally, stainless steels are durable because they are strong and tough and offer high resistance to rust. Various applications require materials that will be able to last for a very long period of time for instance, marine applications.

304 stainless steel offers that kind of durability to manufacturers and consumers. Durability also ensures lower maintenance and operational costs leading to high savings.

Workability

When we talk of workability, we mean that 304 stainless steel is easy to form and fabricate with simple maintenance procedures. The material can be cleaned easily through methods like dry vapor cleaning or steam cleaning. Activities such as bending, forming, cutting, welding and finishing can be carried out easily on 304 stainless steel.

Corrosion Resistance

304 stainless steel can resist chemicals, acids, salts and other corrosive agents making it suitable for various applications. Due to the low carbon content, 304 stainless steel is less susceptible to corrosion.

Salt water, for marine structures can be resisted when the components are made from 304 stainless steel. 304 stainless steel is covered by an oxide layer that protects the alloy from the surrounding environment.

Impact Resistance

304 stainless steel offers high impact resistance since it is tough and mechanically strong. The material is usually recommended when high strength and durability is required for applications used in low-temperature environments. Unlike 316 stainless steel, 304 stainless steel is not suitable for applications in high-temperature environments.

Nonferrous Properties

304 stainless steel is nonmagnetic material and can be used in various applications.

Benefits 316 Stainless Steel

Benefits 316 Stainless Steel
Benefits 316 Stainless Steel

Corrosion Resistance

Grade 316 stainless steel contains molybdenum which is responsible for the enhanced resistance to corrosion. Other alloys, such as 304 stainless steel, offer resistance to corrosion but not in the same way grade 316 stainless steel does. This property prevents pitting in chemical or corrosive environments reducing corrosion.

Durability

Every company desires a material that will serve long enough to realize their expenditure and offer a long-term profit. 316 stainless steel is very tough and can stand high impact procedures and still serve for a long period of time. Durable brackets are an example of an application made from 316 stainless steel and they are exposed to repeated impact processes.

Resistance to Chloride Pitting

In marine applications, most metals cannot be of service to the continuous exposure to salts and chlorides that eat away metals. Chlorides can even destroy the oxide layer on the 304 stainless steel forming rust. Therefore, most marine applications use 316 stainless steel as the greatest corrosion resistant alloy.

High Thermal Stability

Applications that require high temperature environments can comfortably use 316 stainless steel because it has high thermal stability. Compared to 304 stainless steel, 316 stainless steel is much more stable at elevated temperature.

High weldability

Weldability is the ability of a material to be joined together with similar or different materials for various applications. For joining parts to take place, the material must be formable and 316 is easy to weld and form. It means machining processes can also happen with ease.

304 Stainless Steel Properties

304 Stainless Steel Properties
304 Stainless Steel Properties

Mechanical Properties of 304 Stainless Steel

  • High tensile strength of up to 700MPa for sheets 8mm thick.
  • High impact strength of about 220 MPa for sheets up to 8mm thick.
  • Elongation can take place up to 55% with a sheet of 8mm thick.
  • Hardness is up to 202 HB for sheets of about 8mm thick.

Physical Properties of 304 Stainless Steel

  • Density of up to 7,900 kg/m³.
  • Melting point of approximately 1400 to 1450°C.
  • Modulus of Elasticity at 20°C is approximately 193 GPa.
  • Shear Modulus at 20°C is about 77 GPa.
  • Poisson’s Ratio at 20°C is about 0.30.
  • Thermal Conductivity at 100°C is about 16.2W / m. °C.
  • Electrical Resistivity at 25°C is 0.72micro-ohm. m.
  • Electrical Conductivity at 25°C is 1.25% IACS.
  • Specific Heat is about 500J/kg. °C.
  • Relative Magnetic Permeability is 1.02.
  • Coefficient of Expansion at about 0 – 100°C is at 17.2/°C.

Toughness – 304 stainless steel is inherently tough and can maintain ductility to absorb high impact situations.

High temperature – The allowable application temperature for 304 stainless steel when being used in an intermittent process is 9250C. For applications under continuous processes, the allowable temperature is 8700C

Cold fabrication – 304 stainless steel allows for workability through standard sheet working methods except oxygen cutting.

Heat treatment – annealing through solutions can be done at temperatures of about 1065 to 11200C and cooled rapidly to avoid precipitation. 304 stainless steel does not undergo hardening through theat.

Forging – 304 stainless steel is easy to forge only at temperatures not below 9250C.

Difference Between 304 And 316 Stainless Steel

Difference Between 304 And 316 Stainless Steel
Difference Between 304 And 316 Stainless Steel

Chemical Composition

304 stainless steel is made up of 18% chromium and 8% nickel and other components. On the other hand, 316 stainless steel is made up of 16% chromium, 2% molybdenum and 10% nickel.

Mechanical Properties

  • Tensile strength – refers to the ability to resist breakage.

304 stainless steel of approximately 8 to 75 mm thick presents a tensile strength of about 520 to 720 MPa.

On the other hand, 316 stainless steel of the same thickness presents tensile strength of 530 to 750MPa.

  • Yield strength – refers to the ability to resist deformation

316 has a higher yield strength of about 290MPa compared to 304 stainless steel with a yield strength of 215MPa.

  • Hardness – the ability to resist abrasion, indentation, deformation, penetration.

316 is harder with a hardness of 79 Rockwell B compared to 304 stainless steel with 70 Rockwell B.

  • Elasticity – the ability to stand stress.

304 stainless steel responds better to stress with a modulus of elasticity at 200GPa compared to 316 with 164GPa.

Corrosion Resistance

316 stainless steel has higher resistance to corrosion compared to 304 stainless steel.

Temperature Resistance

304 stainless steel has a higher temperature resistance compared to 316 stainless steel. However, 316 stainless steel offers more thermal stability compared to 304 stainless steel.

Durability

The two grades are durable, however, 316 is more durable due to high corrosion resistance.

Cost Difference

316 stainless steel is more expensive compared to 304 stainless steel due to the extra elements in the alloy.

316 Stainless Steel Properties

316 Stainless Steel Properties
316 Stainless Steel Properties

Mechanical Properties

  • Tensile strength of up to 700MPa for sheets 160mm thick.
  • Proof stress of 200 Min for sheets up to 160mm thick.
  • Elongation ability of 40 Min %
  • Hardness of 215 for 160mm sheets.

Physical Properties

  • Density of about 8.00 g/cm3
  • Melting Point at 1400°C
  • Modulus of Elasticity of 193 GPa
  • Electrical Resistivity approximately at 0.74 x 10-6 Ω.m
  • Thermal Conductivity of about 16.3 W/m.K
  • Thermal Expansion of 15.9 x 10-6/K

Heat treatment – 316 stainless steel is not hardened through heat treatment.

Cold working – cold working can harden and strengthen 316 stainless steel

Weldability – 316 stainless steel is highly weldable with or without fillers.

Uses Of 304 Stainless Steel

Consumer Goods
Consumer Goods

Kitchen sinks and other consumer products that are meant to last for a long period of time. Other products include toys, home furniture and many other consumer products.

Chemical Industry
Chemical Industry

Chemicals are corrosive and most metals cannot resist this kind of corrosion, which is why 304 stainless steel is used. Chemical storage tanks and chemical transportation tanks are made from 304 stainless steel.

Manufacturing Industry
Manufacturing Industry

During fabrication processes such as welding or when joining parts, fasteners and flanges are used. These products must be hard and strong and they are made from 304 stainless steel.

Construction Industry
Construction Industry

Roofing, cladding, doors and windows are made from 304 stainless steel material due to its strength and durability.

Uses Of 316 Stainless Steel

Food Industry
Food Industry

In the food industry, products such as food processing equipment and brewery or dairy equipment are made from 316 stainless steel. This material is preferred because it is highly durable and easy to clean.

Pharmaceutical Industry
Pharmaceutical Industry

Medical equipment such as beds, benches, laboratory machines and many other products are made from 316 stainless steel. Other products made from 316 stainless steel include medical implants, chemical equipment etc.

Marine Applications
Marine Applications

316 stainless has high corrosion resistance and can also resist corrosion due to chlorides protecting structures from rust and pitting.

People Also Ask:

Is 304 Stainless Steel Better Than 316 Stainless Steel?

304 stainless steel is better in terms of purchasing costs, however, 316 is better in terms of corrosion resistance and durability.

Which Is Stronger Between 304 And 316 Stainless Steel?

316 stainless steel is stronger than 304 stainless steel because it has a higher tensile strength.

Will 316 Stainless Steel Rust?

Molybdenum component in the 316 stainless steel makes it resistant to rust.

How Does Salt Affect Stainless Steel?

The chloride in salt is very corrosive and longer periods of exposure to salts may leading to corrosion especially with 304 stainless steel.

How Does Price Of 304 Stainless Steel Compare To 316 Stainless Steel?

The cost of 316 stainless steel is 75% higher than that of 304 stainless steel because of the extra chemical components.

More Resources:

Stainless Steel Fabrication

Stainless Steel

Stainless Steel Alloy

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