Steel welding is an intricate topic with many different considerations which need to be taken into account. This article presents some of the key factors which affect steel welding for low carbon steels (the most widely used steel kinds).
Carbon (C) Content
High carbon content can increases the hardness of steel, making it prone to cracking during welding. Conversely, if the carbon content is too low (< 0.12%), then the steel is susceptible to porosity issues (entrapment of gases in the metal or the weld). For structural steel which needs to be welded together, the carbon content should ideally be 0.15% ≦ C ≦ 0.2%.
Manganese (Mn) Content
The presense of Manganese (Mn) in structural steel is helpful to prevent porosity related issues (as well as Silicon (Si) content). In general, steel with up to 0.9% manganese content possess good weldability.
Chemical Composition
The presence of certain elements, such as sulfur and phosphorus, can make steel more difficult to weld.
Thickness
In general, thicker steel is more difficult to weld than thinner steel since it may require multiple passes along the joint to be welded. Additionally, care must be taken with thinner steels since there is a danger of significant deformation due to welding.
Hardness
Hard steel is more difficult to weld than softer steel.
Type of Weld
Certain weld types, such as fillet welds, are easier to weld than others, such as butt welds.
Welding Process
Certain welding processes, such as stick welding, are more difficult to use on structural steel than others, such as gas metal arc welding (GMAW) or gas tungsten arc welding (GTAW).
Surface Condition
Rust and other surface contaminants can negatively affect weldability.