Within the steel world, “carbon steel” is a term given to steel that covers several different chemical compositions. Carbon steel is a large category composed mostly of iron, but there are other elements that can be added that affect its properties, and particularly its weldability.

For any welding project, knowing what type of carbon steel is involved is vital. At Wasatch Steel, we have all the steel and welding materials you’ll need to proceed with such projects. Here are some basic variables you’ll need to know about carbon steel welding.

Carbon Levels

One of the most important things to remember when welding carbon steel is the actual carbon content. This will generally range from nearly zero carbon to about 2.1 percent by weight. There are three classifications for carbon content:

• Low carbon steels: Less than approximately 0.30 percent carbon.
• Medium carbon steels: Approximately 0.30-0.60 percent carbon.
• High carbon steels: Approximately 0.61-2.1 percent carbon

Each type will require different considerations when being welded. Low carbon steel can most easily be welded in a room temperature environment, while medium carbon steel requires pre-heat and post-heat treatment to avoid cracking. High carbon steel is most prone to cracking, and will require very thorough pre-heating and post-heating, plus special filler materials in some cases.

Equivalency

The carbon equivalency formula, which also accounts for other elements besides carbon that may affect weldability, can also be used. The higher carbon equivalent, the less weldable steel will be. Pre-heat and post-heat processes will have to be introduced to prevent cracking.

Cooling Rate

High cooling rates also increase likelihood of cracking, and carbon steel with higher carbon quantities will require slower cooling rates to prevent this. There are a number of factors that go into cooling rate, including thickness of steel and ambient temperature.

Additional Considerations

In some cases, elements found in carbon steel simply won’t be conducive to welding no matter what additional processes are included. Leaded steels should generally be avoided due to the way it can promote solidification cracking of welds, and sulfur and phosphorous may also have cracking effects – anything over 0.05 percent of either of these could lead to solidification cracking.

For more information on carbon steel welding, or to buy steel online today, speak to our experts at Wasatch Steel.