Carbon steels represent the basic group of alloys used for general application where tensile and moderate ductility are required. They also provide a material which is readily weldable to other components either under controlled shop conditions or in field fabrication situations.
The alloys are characterized by the presence of less than .50% C along with Mn for strengthening and Si for castability improvement. Other alloying elements are only present as residual constituents in this group and must be maintained at relatively low levels to allow for proper welding capabilities. Melting of these alloys require attention to the problem that they are gas pickup prone. They will pick up H from anything wet in the charge and they will pick up N from the atmosphere if held liquid in the furnace. Their melting is further complicated by the absorption of O from the atmosphere and requires exacting additions of Al to offset this tendency.
The higher C content steels in this group provide a general application alloy fatigue resistant service. This characteristic is greatly enhanced when the parts are heavily shot blasted as a final finishing department processing.