Metal strength at tension
About project (Technical and scientific aspects).
In previous project “Extrusion” were revealed some contradictions in traditional description of the compression stress-strain state. It was naturally supposed that the same contradictions exist in standard representations of others types of loading. Tensile test is the determinative one for Strength of Materials (Material Resistance to Strain) theory. Therefore the process of tensile test of the metal polycrystals was chosen for the analysis. It is the subject of interest for engineers. Of course contradictions in theoretical representations were confirmed. Particularly, the surface growth at tension was revealed, include the plastic state also. This was taken as the evidence of transverse direction of irreversible mass transfer. The same as at compression, principal stresses ratio was formulated. As the direct consequence – non uniform stresses distribution along the specimen section occurs. Some attempts to define conformity (correlation) between stresses and strains were not successful. Several samples of loading diagrams of known sources were processed with approximation. Finally it was concluded that one-to-one conformity does not exist. I.e.: 1) all statements which are based on the known load diagram are physically incorrect; 2) the analysis results may not be rightful without revealing of the plastic strain physical mechanism. 3) it’s worth to study the mechanism from the point of view of single crystal tension. Therefore, the analysis of single crystal at tension were fulfilled [1].
As analysis results – the physical mechanism of the plastic strain at tension was revealed.
The analysis may be appraised as preparation for solution of the particular problem – increase in strength of metals at tension. (The project name)
Superficial analysis of single crystal at tension
(Engineer view)
About article
The aim of presented paper is to find solutions for several contradictions in physical rational of poly crystals tension tests. Poly and single crystals physical properties similarity has sufficient evidences. Two essential disadvantages were revealed in traditional theoretical grounds of single crystal plastic strain. The first relates to dislocation theory. It characterized of rather high level of abstraction. This not allow to define clearly causal relationship of the changes in specimen during plastic strain starting. The second is that, all theories of plastic flow are based on the shear strain. This historically prevailing view does not satisfy to physical changes in specimen, especially on the first stage of plastic shaping.
The new physical model of plastic changes process was developed in the paper. At the core the process occurs by the mass transfer in the transverse direction relative to tension axis. As the initial the uniform stress – strain state in terms of principal components was used. The plastic changes in specimen were examined with two concepts: continuous medium and crystalline regular structure. The process represents as a result of surface atoms displacement which apprised with relative interaction changes. The numerical estimation of the process parameters for Fe single crystal specimen was fulfilled. The new model of single crystal plastic flow allows to present the most of inherent physical effects as direct its consequence: yielding limit; yielding “tooth”; surface increase; Piobert – Luders bands appearance; the relaxation phenomenon; Bauschinger’s effect; nonlinear elasticity; as the most significant – load capacity limitation. The paper contains helpful material for solutions of some contradictions of poly crystal plastic flow at tension.
DOI EN: 10.48348/CRYST.2020.96.64.001
DOI RU: 10.48348/CRYST.2020.98.97.002
Rehbinder Effect
About article
The article above was submitted to JAP journal on 5th of October 2020. It was rejected on 6th of October with the notes – not “meet to the Journal acceptance criteria. Journal of Applied Physics considers for publication manuscripts reporting on original research results that significantly advance understanding in contemporary applied physics.
DOI: 10.48348/g2561-3319-9991-t
DOI: 10.48348/y2759-9563-2306-u
On Single Crystal Strength Dependence on Size
About the Article.
The question, why the strength of single crystal depends on its size, was not answered in the previous article. Therefore, the subject was developed in this article. The article complements the concept of transverse direction of plastic strain at tension.
Abstract.
Size effect is defined as strength dependence on size at tensile test of single crystal. The only geometric factor influences on the effect is considered in this paper. Geometric factor includes two characters: specimen round cross section and micron sized diameter. The rest of the factors were not considered.
The article was submitted to publication and was not published.
DOI: 10.48348/c4678-7397-3975-n
Polycrystalline Metals Strength at Tension
About the Article.
Stage ll Hardening. Surface contribution on strength. Plastic Strain mechanism. Porteven Le Chatelier Effect. General Problem Formulation.
The present paper includes some preliminary steps before Experimental Research Program of the metal strength at tension, should be performed.
10.48348/d8022-0303-3510-u