Carbon Steel
A form of steel known as carbon steel is one with a carbon content of
more than 0.02% and less than 2% (steel with a carbon content of more than 2% is
known as cast iron, and steel with a carbon content of less than 0.02% is known as
wrought iron). Furthermore, it has the highest production of any metal material.
It is typically used on metal components like cutting tools, steel cables, piano
wires, springs, and knives that must be strong, hard, and wear-resistant. The pieces
often need to be treated and tempered after being processed. After heat treatment,
steel with a higher carbon content has greater hardness, strength, and wear
resistance. High-carbon, medium-carbon, and low-carbon steel are the three
categories of carbon steel.
Types of carbon steel
Low-carbon steel
Usually have a carbon content of between 0.04% and 0.30%. The largest
category of carbon steel is this one. The shapes it covers range greatly, from Flat
Sheets to Structural Beams. Other elements are decreased or increased based on the
desired qualities required. It is flexible, malleable, and soft. Steel bars,
stamping-resistant components, specific steels, etc., are among the things it mostly
produces. The surface hardness of low-carbon steel can be improved through the
carburizing process, making it more abrasion resistant and boosting its strength
even further.
Properties of low carbon steel
- High toughness
- Low tensile strength
- High weldability
- Low cost
- High ductility
- Low hardness
- High machinability
Medium carbon steel
It has a typical carbon value between 0.31% and 0.60% and a manganese
content between.060% and 1.65%. Although this product is more difficult to mold,
weld, and cut than low-carbon steel, it is stronger. Heat treatment is a common
method for hardening and tempering medium carbon steels. It is ideal for producing
products like gears and studs that will endure a lot of wear and tear. Medium carbon
steel can be heated and maintained at a constant temperature until it reaches the
desired hardness, then soaked and cooled if more hardening is required. The
production of stainless steel is the primary goal.
Properties of medium carbon steel
- Medium strength
- Moderate toughness
- Medium weldability
- Medium ductility
- Moderate machinability
High-carbon steel
It is frequently referred to as “carbon tool steel” and usually contains
carbon content between 0.61% and 1.50%. Cutting, bending, and welding high-carbon
steel is particularly challenging. It gets exceedingly hard and brittle after being
heated. High-carbon steel can be made with chromium and manganese alloys added to
assist the material resists corrosion. The primary applications are steel doors,
rails, knives, general bearings, and steel frame molds (used to shape steel).
Properties of high carbon steel
- High toughness
- Low machinability
- High strength
- Moderate weldability
- Low ductility
Chemical Composition of Common Low Carbon Plate Grades
|
Grade |
Carbon Max |
Manganese |
Phosphorus Max |
Sulfur Max |
Silicon |
|
A36 up to 3/4” thick |
0.25% |
N/A |
0.030% |
0.030% |
0.40% Max |
|
A36 >3/4 – 1 ½” thick |
0.25% |
0.80-1.20% |
0.030% |
0.030% |
0.40% Max |
|
A36 > 1 ½ - 2 ½” thick |
0.26% |
0.80-1.20% |
0.030% |
0.030% |
0.15-0.40% |
|
A36 >2 ½ - 4” thick |
0.27% |
0.85-1.20% |
0.030% |
0.030% |
0.15-0.40% |
|
A36 >4” thick |
0.29% |
0.85-1.20% |
0.030% |
0.030% |
0.15-0.40% |
|
A572 Grade 42 |
0.21% |
1.35% |
0.030% |
0.030% |
0.15-0.40% |
|
A572 Grade 50 |
0.23% |
1.35% |
0.030% |
0.030% |
0.15-0.40% |
|
A830 Grade 1020 |
0.18-0.23% |
0.30-0.60% |
0.030% |
0.030% |
N/A |
Mechanical Properties of Common Low Carbon Plate Grades
|
Grade |
Yield Point |
Tensile |
|
A36 |
36 ksi |
58-80 ksi |
|
A572 Grade 42 |
42 ksi |
60 ksi |
|
A572 Grade 50 |
50 ksi |
65 ksi |
Chemical Composition of Common Medium Carbon Plate Grades
|
Grades |
Carbon |
Manganese |
Phosphorus Max |
Sulfur Max |
Silicon |
|
A516 Grade 70 >2” & ≤4” thick |
0.30% |
0.85-1.20% |
0.025% |
0.025% |
0.15-0.40% |
|
A516 Grade 70 >4” thick |
0.31% |
0.85-1.20% |
0.025% |
0.025% |
0.15-0.40% |
|
A830-1045 |
0.43-0.50% |
0.60-0.90% |
0.030% |
0.030% |
N/A |
Mechanical Properties of Common Medium Carbon Plate Grades
|
Grades |
Yield Point |
Tensile |
|
A516 Grade 70 |
38 ksi |
7-90 ksi |