There are numerous grades of steel available for a variety of applications. The American Iron & Steel Institute (AISI) has organized steel grades in different classes based on specific physical properties.
The Society of Automotive Engineers (SAE) also works hand in hand with AISI to come up with accurate naming structures that outline the mechanical and physical differences between each grade of steel.
In this article, we’ll be taking a look at the 52100 grade, in particular. What it’s made of, how to differentiate it from other grades of steel, and what the different applications for it are.
Let’s get started!
What Do the Numbers Mean?
The structure and physical properties of steel are expressed by a specific numbering structure. For example, the first digit of 52100 steel is five, which indicates that it was mostly alloyed with chromium.
The second digit is two, indicating that the percentage of alloying is greater than 1%. Now, this doesn’t mean that this steel was alloyed by 2%; it just means that whatever alloying percentage this steel has, it’s greater than 1%.
Finally, we have the last three numbers: 100. This is an indicator of the average percentage of carbon found in this type of steel. 52100 steel has around 1% of carbon in its composition.
Here are the specific elements in 52100 steel:
- 1.3% to 1.6% Chromium
- 0.98% to 1.1% Carbon
- 0.25% to 0.45% Manganese
- 0.15 to 0.3% Silicon
- Less than 0.025% Sulfur
- Less than 0.025% Phosphorus
Learn more about steel’s coding system.
Why Does Chromium Matter in Steel?
The addition of chromium allows for the reduction of the carbide size. This can be advantageous in the resistance to fractures and the overall toughness of the steel. Since smaller carbide particles don’t negatively affect toughness or hardness, 52100 steel must have a significant amount of chromium to produce machinable metals.
Alloy steels, like 1095, don’t have chromium, so the carbide particle size is large. This might give it much higher wear resistance, but it’s likely these types of steel will crack under large shear forces.
Finally, 52100 steel is annealed before being sent to the customer. It’s cooled down from incredibly high temperatures to form pearlite. Then, the steel is exposed to intermediate treatment at lower temperatures to ‘spheroidize’ the pearlite. This produces the small-sized carbides and gives it a soft finish and sets it up for one last heat-treatment process.
Physical Properties of 52100 Steel
52100 steel has a density of 7.81 g/cm3 (around 0.28 lb/in3). This high-carbon, high-chromium steel can be hardened by hot and cold processes and has a good response to annealing and tempering. It can also be strengthened using specific heat processes.
You’ll find 52100 steel formed, forged, or machined. It can come in wires, tubes, stocks, or even flat-rolls.
Elasticity Modulus
Elasticity is an important factor in steel. Smaller elasticity modulus can gum on the mills and gall up the machine, so the larger elastic modulus of the 52100 steel makes it suitable for its manufacturing applications.
52100 steel has an elasticity of 210 GPa. We consider this the sweet spot in terms of elastic stiffness, as stiffer steel can burden the machines and wear them out significantly faster.
Bulk Modulus
Another important aspect is the bulk modulus. It’s usually reserved for liquids, but can be an accurate indicator of the steel’s resistance to compression.
In manufacturing, the bulk modulus is vital in determining the loss of volume during uniform compression.
52100 is mainly used in ball bearings, so it’s essential to study the metal under the constant forces of compression. 160 GPa is considered much more durable than aluminum alloys, almost twice as strong.
Shear Modulus
The shear modulus is used to measure the steel’s tolerability towards stress. When two forces come against each other along the material’s plane, this is called shear force. In the case of 52100 steel, shear stress is common across all applications.
Steel with a low shear modulus can fracture or not shear off properly. It’s important to know if the metal will be twisted radially or completely cut from the stock.
In the case of 52100 steel, the shear modulus is 80 GPa, which is ideal for flat roll cutting and wire cutting.
Fracture Toughness
Steel applications require relatively high fracture toughness. This is an indicator of the steel’s capability to resist fracture or cracks.
Steel can be subjected to incredible amounts of stress, as long as the stress falling on it doesn’t cause cracks to spread along its surface.
It’s vital to study the manufacturing process to determine whether the 52100 steel will endure the amount of stress or surrender completely and shatter.
52100 steel has a fracture toughness of 15.4 to 18.7 Mpa-m1/2. It’s definitely on the durable side, but you might see some ductile fractures under immense forces.
Machinability
Finally, machinability is an indicator of how well steel reacts with manufacturing processes. Machinability is measured by percentage. Anything lower than 100% isn’t ideal for machining procedures, as referenced by AISI.
52100 steel is given 100% machinability. It’s suitable for most applications, but there are instances of die wear where the machines mill steel bits faster.
Applications of 52100 Steel
There are numerous applications of 52100. It’s most commonly used for bearing equipment, vehicle parts, mill rolls, and much more. Although it’s renowned for its hardness, strength, and flexibility, it’s not commonly used in welding.
Here are all the common applications of 52100 steel.
- Bill bearings
- Mill rolls
- Tapes
- Dies
- Taps
- Automotive parts
- Fasteners
- Aircraft parts
Wrapping Up
52100 steel is considered ideal for various manufacturing applications. Bearing manufacturing equipment relies on 52100 steel for its exceptional hardness and toughness. It’s also a popular choice in cutlery and blades.
It’s important to study the steel’s specifications before getting into a new manufacturing project. If you don’t have access to 52100 steel, contact your supplier and see if they can offer you a suitable alternative.