Carbon and ferritic-alloy steels

Abstract

It is the intention to discuss in this chapter those steels that have a body-centred cubic form at or above normal atmospheric temperature. Included are carbon steels with carbon contents up to 1·0%, carbon-manganese steels with manganese content up to 1·6%, and steels containing other alloying elements up to the martensitic type of 12% Cr steel and maraging nickel steel. Higher-alloy ferritic and ferritic/austenitic steels are also included, although they may not suffer an α to γ transformation. Other than this last group, the common feature about these alloys is that they may all, to a greater or lesser degree, be hardened as a result of passing through the weld thermal cycle and may therefore suffer a change in properties in the region of a fusion-welded joint. General metallurgical questions will be considered first, and a later section will deal with the individual alloys and alloy groups that are used in welded fabrication. Cast iron is included in the material groups since, from a welding viewpoint, it suffers the same type of transformation in the HAZ of fusion welds as steel, albeit in an extreme form.