After alloying elements in steel, mainly in three forms in the presence of steel. Namely: the iron to form a solid solution; and carbon form carbides; in high alloy steels is also possible to form intermetallic compounds.
1. dissolved iron
Almost all of the alloying elements (except Pb) can be dissolved iron to form an alloy ferritic or austenitic alloy, according to the role of α-Fe or γ-Fe on, alloying elements can be divided into expanded austenite bulk region and reduce the austenite phase region into two categories.
Expanding element γ-phase region - also known as austenite stabilizing elements, primarily Mn, Ni, Co, C, N, Cu, etc., which makes A3 point (transition point γ-Fe α-Fe) is decreased, A4 point (transition point γ-Fe) is increased, thereby expanding the range of the presence of γ- phase. Wherein after Ni, Mn, etc. is added to a certain amount, γ-phase region can be extended to below room temperature, so that α phase region disappears completely expand the γ phase region called elements. Other elements (e.g., C, N, Cu, etc.), although the expansion of γ-phase region, but can not be expanded to ambient temperature, part of the expansion element so called γ-phase region.