Carbon Steel: Properties, Production, Examples and Applications
Carbon steel is an iron-carbon alloy, which contains up to 2.1 wt.% carbon. For carbon steels, there is no minimum specified content of other alloying elements, however, they often contain manganese. The maximum manganese, silicon and copper content should be less than 1.65 wt.%, 0.6 wt.% and 0.6 wt.%, respectively.
Types of carbon steel and their properties
Carbon steel can be classified into three categories according to its carbon content: low-carbon steel (or mild-carbon steel), medium-carbon steel and high-carbon steel . Their carbon content, microstructure and properties compare as follows:
| Carbon content (wt.%) | Microstructure | Properties | Examples | 
| Low-carbon steel | < 0.25 | Ferrite, pearlite | Low hardness and cost. High ductility, toughness, machinability and weldability | 
| Medium-carbon steel | 0.25 – 0.60 | Martensite | Low hardenability, medium strength, ductility and toughness | 
| High-carbon steel | 0.60 – 1.25 | Pearlite | High hardness, strength, low ductility | 
Carbon Steel Description
Grade:
1)GB: Q195, Q215, Q235A, Q235B, Q235C, Q235D, Q255A, 255B, Q275, Q295A, Q295B, Q345B, Q345C, Q345D, Q345E, Q390A, Q390B, Q390C,Q390D, Q390E, Q420, Q420B, Q420C, Q420D, Q420E, Q460D, Q460E, Q500D, Q500E, Q550D, Q550E, Q620D, Q620E, Q690D, Q690E
2)EN: S185,S235JR, S275JR, S355JR, S420NL, S460NL S500Q, S550Q, S620Q, S690Q 
3)ASTM: Grade B, Grade C, Grade D, A36, Grade 36, Grade 40, Grade42, Grade 50, Grade 55, Grade 60, Grade 65, Grade 80 
4)JIS: SS330, SPHC, SS400, SPFC, SPHD, SPHE
PRODUCT DETAILS
| 1018   Cold Rolled Steel Coil | 
| 1018   cold rolled steel coil is made of a general-purpose, low-carbon steel with   good case hardening qualities. It is especially suited to cold   forming and bending operations. 1018 steel is suitable for parts   that require cold forming such as crimping, swaging, or bending. 1018 steel is mild steel with   medium-low carbon content. AISI 1018 carbon steel is a free machining grade   that is the most commonly available grade around the world. Although its   mechanical properties are not very unique, it still can be easily formed, machined,   welded and fabricated. | 
| Product
  Parameters | 
| Product Name | 1018
  Cold Rolled Steel Coil | 
| Production
  Process | Hot Rolling,
  Cold Rolling | 
| Material
  Standards | AISI, ASTM,
  ASME, DIN, BS, EN, ISO, JIS, GOST, SAE, etc. | 
| Width | 100mm-3000mm | 
| Length | 1m-12m, or
  Customized Size | 
| Thickness | 0.1mm-400mm | 
| Delivery
  Conditions | Rolling,
  Annealing, Quenching, Tempered or Standard | 
| Surface
  Process | Ordinary, Wire
  Drawing, Laminated Film | 
| Chemical
  Composition | 
| Element | Content (%) | 
| Manganese,
  Mn | 0.60-0.90 | 
| Carbon, C | 0.15-0.20 | 
| Sulfur, S | 0.05
  (max) | 
| Phosphorous, P | 0.04
  (max) | 
| Iron, Fe | Balance | 
| Mechanical
  Properties | 
| Properties | Metric | Imperial | 
| Tensile
  strength | 440 MPa | 63800 psi | 
| Yield strength | 370
  MPa | 53700
  psi | 
| Modulus of elasticity | 205
  GPa | 29700
  ksi | 
| Shear modulus (typical for steel) | 80
  GPa | 11600
  ksi | 
| Poisson’s ratio | 0.29 | 0.29 | 
| Elongation at break (in 50 mm) | 15% | 15% | 
| Hardness, Brinell | 126 | 126 | 
| Hardness, Knoop (converted from Brinell hardness) | 145 | 145 | 
| Hardness, Rockwell B (converted from Brinell hardness) | 71 | 71 | 
| Hardness, Vickers (converted from Brinell hardness) | 131 | 131 | 
| Machinability (based on AISI 1212 steel. as 100 machinability) | 70 | 70 | 
| Scope of
  Application | 
| AISI
  1018 carbon steel is commonly used in high volume screw machine parts
  applications. The other applications of this alloy are as follows: | 
| ● Shafts | 
| ●
  Spindles | 
| ● Pins | 
| ● Rods | 
| ●
  Sprocket assemblies. |