Influence of special features of the gradient structure formation during severe plastic deformation of alloys with different types of a crystalline lattice

Abstract

Problem Statement (Relevance): The paper describes some features and prospective benefits of deformation by methods of drawing with shear (SD) and high pressure torsion (HPT) in a temperature range of dynamic strain aging (DSA) effect, which allow receiving a high complex of physical and mechanical properties. Objectives: The study aims to investigate and analyze features of the structure formation with the combined application of severe plastic deformation (SPD) and the DSA effect during deformation by drawing with shear and high pressure torsion, to establish patterns of the gradient structure formation. Methods Applied: 1. Computer simulation in Deform 3D software to investigate the stress-strain state on materials with various types of a crystalline lattice: copper grade M1 (FCC), Steel 10 (BCC) and titanium VT1-0 (HCP) and a further comparison with experimental results. 2. Microhardness measurement 3. Scanning and transmission electron microscopy. Originality: This research resulted in investigation of the combined effect of the DSA effect and SPD on the gradient structure formation and mechanical properties of metals with various crystalline lattices. Findings: the paper presents the results of the study of the structure formation during non-monotonous plastic deformation of the alloys (steel 10, copper and titanium) with various crystalline lattice types by SD, as well as ECAP and HPT of low-carbon steel in the temperature range of the DSA effect. Deformation mechanisms and features of the deformation behavior on a mesoscopic scale under various deformation treatment modes are analyzed. The temperature range of the DSA effect in steel 10 under ECAP and the fact of the gradient structure formation under HPT are established. Practical Relevance: The study helped to obtain data that can be used to choose the optimal deformation treatment mode with the DSA effect.

Formation of a Gradient Structure in Austenitic Stainless Steel AISI 321 by Radial-Shear Rolling

“…Such a material becomes brittle and prone to destruction when stretched. The use of metal materials with a gradient structure [11][12][13][14][15][16], where the grain size from the coarse-grained state in the central part of the workpiece decreases to the ultra-fine-grained state on the surface, is an effective way to solve the problem of increasing the plasticity of metal products in general.…”

Microstructure and Physico-Mechanical Properties of Biocompatible Titanium Alloy Ti-39Nb-7Zr after Rotary Forging

“…The chemical composition of the alloy was selected based on the recommendations outlined in [17] and it is detailed in Table 1. Based on the chemical composition of the investigated alloy, the stability of the β-solid solution to transformations during cooling and deformation was estimated using literature data on molybdenum equivalent ([Mo] eq = %Mo + 0.33%Nb + 0.31%Zr + 1.93%Fe + 1.84%Cr + 2.46%Ni [33]), B o (binding strength), M d (energy level of the metallic d-orbital) [34,35], as well as β-transus temperature (β tr = 885 − 8.5Nb − 2Zr [24]) and the martensite start temperature M S [36,37]. The computed results are summarized in Table 2.…”

“…Currently, traditional metal forming processes are being developed to provide strengthening comparable to SPD methods. Rotary forging (RF) is one such promising metal-forming process [23,24]. RF achieves a compression stress state along the radius of the rotating workpiece by utilizing cyclically converging dies.…”

Realization of the innovative potential of radial-shear rolling for forming the structure and mechanical properties of AISI-321 austenitic stainless steel

“…Such material becomes brittle and is subjected to destruction. The use of metal materials with a gradient structure [7][8][9][10], where the grain size from the coarse-grained state in the central part of the workpiece decreases to the ultra-fine-grained state on the surface, is an effective way to solve the problem of the plasticity increasing of metal products.…”