Residual Stress Determination in the Cementite and Ferrite Phases of High Carbon Steel

Abstract

The paper describes a study of the residual stress and the texture in cold drawn wires of pearlitic high carbon steel. Total true strains in wire drawing ranged from 1.96 to 2.59. Such material consists of a ferrite and a cementite phase, both in lamellar form. First, a discussion is given as to the various types of residual stresses which can be expected in such a material (macrostresses, grain microstresses, phase microstresses and their components). Next the measurements which have been carried out are described: neutron diffraction measurements on both cementite and ferrite phases in the bulk of the wires, and X-ray diffraction measurements on the ferrite phase at the surface. Neutron diffraction led to the average texture and the average phase microstresses in the axial direction in both the ferrite and the cementite phases. X-ray diffraction led to the total phase stress at the surface of the ferrite. By combining both results, it turned out to be possible to determine the macrostress at the surface of the wires and the total phase stress in the cementite as well. Additional measurements, performed after chemical thinning of the wires, finally led to some information about the stress gradients.