Surface Purity Effect on Irregularities of Changes in Deformation Texture of Zr-2.5% Nb Alloy

D.g Malykhin ,V.m Grytsyna ,Yuri V Gorbenko ,Iryna G Tantsura ,K.v Kovtun ,Г П Ковтун ,Tetiana Yurkova ,V.d Virych ,V.n Voyevodin

doi:10.26565/2312-4334-2021-1-07

Abstract

This work is a continuation of a series of works on the study of regularities and structural mechanisms of changes in characteristics of crystallographic texture during cold deformation of plates made of Zr2.5%Nb alloy. Effects of influence of surface cleanliness of the plates on the textural regularities during their rolling were investigated. For this, longitudinal fragments of the tube Æ15.0´1.5 mm² were used, flattened, annealed at 580°C in a vacuum of 1.5...3.0 Pa and rolled along the axis of the original tube with various degrees deformation up to 56%, which is likened to longitudinal rolling of plates. Techniques of maximally uniform straightening of tube fragments were used. An analysis of the results of studies of textural changes during cross rolling of plates, straightened from rings of the same tube and pretreated under similar conditions, is also carried out. To analyze the results, the method of inverse pole figures was used, which, in these studies, is distinguished by the possibility of achieving satisfactory accuracy in calculating the integral characteristics of texture. On this basis, the Kearns textural coefficient was calculated along the normal to the plates’ plane. Corrections were introduced for texture dissimilarity along the thickness of the plates, which is caused by the unbending of the preliminary blanks. Additionally, the analysis of texture distributions was carried out using original techniques. According to the results obtained – as a result of X-ray measuring from the plates’ surface – oscillations of the course of changes in the texture coefficient were revealed. This is associated with an alternating process of relaxation of residual stresses during deformation. It has been established that this effect is initiated from the near-surface regions, is associated with a near-surface impurity, and in some cases can penetrate to a considerable depth of the plates. The twinning nature of such regularities is confirmed and active systems of twins are noted.

Highlights

An analysis of the results of studies of textural changes during cross rolling of plates, straightened from rings of the same tube and pretreated under similar conditions, is carried out
In view of the fact that the both cross rolling and effect of unbending deformation of the original rings act in a single geometric direction, the additivity of introduction of the correction with achievement of optimal regularity of the corresponding graph in this case is quite obvious
SUMMARY Surface effects of stress relaxation in the plates made from a Zr-2.5%Nb alloy tube 15.0 1.5 mm2 have been studied using the X-ray method of inverse pole figures (IPFs)

Summary

Introduction

An analysis of the results of studies of textural changes during cross rolling of plates, straightened from rings of the same tube and pretreated under similar conditions, is carried out. As in the case of cross rolling of plates with specific preparation conditions (see Experimental) [4], during longitudinal rolling of such a material, oscillations in the TP changes are observed (Fig. 1b).

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Results

Conclusion