Structure changes in invar Fe–Ni and Fe–Ni–C alloys under the deformation by upsetting

Abstract

Changes in the dimensional and microstructural characteristics of the samples of two invar fcc alloys, Fe–35.0% Ni–0.49% Mn and Fe–30.9% Ni–1.23% C, have been investigated by X-ray diffraction, metallographic, and electron-microscopic methods after upsetting with the logarithmic deformations e = 0.5 and 1.1. It has been shown that the regularities of changes in the macroscopic dimensions of the samples, as well as in the parameters of structural elements, which are presented by coefficients of the shape change after upsetting, are common for both alloys, although they have some distinctions. These distinctions are caused by the presence of a second phase in the carbon-containing alloy, which is concentrated predominantly along the boundaries of structural elements and affects the changes in the size and microstructural characteristics, as well as by a higher density and greater uniformity of the defect distribution.