Because of the low carbon steel is with low carbon content, manganese, silicon content is also small, therefore, under normal circumstances will not be welded to produce severe hardening tissue or quenched structure. Low carbon steel welding joints plasticity and the impact good toughness, welding, and generally does not require preheating control layer temperature and after hot, do not have post-weld heat treatment to improve the organization and the entire welding process do not have to take special measures in the process, excellent weldability.

However, in a few cases, welding also difficulties:
(1)Production of converter steel the old smelting method with a high nitrogen content, impurity content, cold brittleness, increased sensitivity to aging, reduce the quality of welded joints, welding deteriorate.
(2) boiling steel deoxidation incomplete higher oxygen content, P impurities such as uneven distribution of localized content will be exceeded, aging sensitivity and cold brittleness sensitivity of hot cracking tendency increases.
(3) The quality does not meet the requirements of the electrodes, so that the carbon in the weld metal, the sulfur content is too high, can cause cracks. Q235-A steel acid electrode welding, such as a factory, because of the electrode covering ferromanganese high carbon content, will cause weld hot cracking.
(4) Some welding method will reduce the quality of the welded joints of the low-carbon steel. Such as electroslag welding line energy, make coarse grained region of the heat affected zone grain looks very bulky caused a serious decline in the impact toughness after welding must be normalized grain refinement to improve impact toughness.

In short, low-carbon steel is with weldability best and most easily welded, all welding methods are applied to a low-carbon steel welding.