On the inner crystalline structure of ferrite and cementite in pearlite

In a previous paper on “The Inner Structure of the Pearlite Grain” read to the Iron and Steel Institute in 1922 the author advanced views on the stereometry of the pearlite grain. It was shown that the angle of inclination of a secant plane ω could be computed from the equation cos ω = Δ0/Δω, (1) where Δ0 is the actual distance between two consecutive cementite or ferrite lamellæ and Δω is the trace of that distance on the secant plane. It follows from (1) that Δω = Δ0 sec ω. (2) As the diameter dc of a cementite lamella or the diameter df of a ferrite lamella is a constant fraction of Δ, it may be assumed that dω = d0 sec ω, (3) where dω is the trace of d0 on the secant plane.