Yield Point in Mild Steel

Nature ◽  
1962 ◽  
Vol 195 (4845) ◽  
pp. 990-991
Author(s):  
T. GLADMAN
Keyword(s):  
Mild Steel ◽  
Yield Point

A Theory of the Yield Point and the Transition Temperature of Mild Steel

1956 ◽  
Vol 23 (2) ◽  
pp. 219-224
Author(s):  
F. Forscher
Keyword(s):  
Transition Temperature ◽  
Mild Steel ◽  
Strain Rate ◽  
Yield Point ◽  
Structural Model ◽  
Yield Criterion ◽  
State Of Stress ◽  
Yield Point Phenomenon ◽  
Stress And Strain Rate ◽  
Temperature Strain

Abstract Experimental results indicate the dependence of the yield-point phenomenon of mild steel on temperature, strain rate, duration of stress, and stress state. This paper proposes a yield criterion which can account for these variables. The theory is developed on the basis of a “structural” model, by which the behavior of microscopic and submicroscopic elements is idealized. The theory postulates as yield criterion a critical number of relaxation centers (active Frank-Read sources) or, equivalently, a critical size of relaxation centers. The transition-temperature phenomenon is considered to be the result of an inhibition of yielding (upper yield point) by means of geometry, temperature and/or strain rate. A relation is given which expresses its dependence on the state of stress and strain rate.

scholarly journals The transition from the elastic to the plastic state in mild steel

1913 ◽  
Vol 88 (605) ◽  
pp. 462-471 ◽  
Keyword(s):  
Stress Distribution ◽  
Mild Steel ◽  
Yield Point ◽  
Testing Machine ◽  
Plastic State ◽  
Inertia Effects ◽  
Direct Bearing ◽  
Minimum Stress ◽  
Complicated Nature

In the ordinary testing of mild steel the yield point is indicated by the sudden extension of the specimen and the accompanying drop of the beam of the testing machine which occur at this point. This fact would suggest that some reduction of the stress in the specimen under test takes place, and autographic records of tests furnish evidence of the existence of a region immediately after yield in which the relation of stress to strain is of a complicated nature, and in which the intensity of the stress is less than that which caused the yield. It has been shown by Sir Alfred Ewing and Dr. Rosenhain that the yield phenomenon is due to the formation of planes of cleavage in the crystals, along which sliding takes place. The fact that a greater stress is required to initiate the sliding movement than to maintain it has a direct bearing upon the stress distribution on surfaces subjected to non-uniform stresses when yield in any part takes place, and the object of the experiments here described was to determine the minimum stress in mild steel during the transition from the elastic to the plastic state. In the usual methods of obtaining autographic records the effect is considerably obscured by the inertia of the loading appliances, and the impossibility of limiting the extension to the degree required, so that the relation of the recorded load to the strain in the region under consideration is, in these circumstances, to a great extent fictitious. Sir Alexander B. W. Kennedy, some 27 years ago, described a method whereby inertia effects were eliminated, and obtained, as a result, a reduction of stress immediately after yield of about 16 per cent. Since the experiments here described by the present writers were carried out, Prof. W. E. Dalby has published an account of an optical autographic recorder, in which the measurement of the load is effected in a manner similar to that adopted by Kennedy, and in tests carried out on mild steel has observed a reduction of stress of about 13 per cent.

scholarly journals Yield Point of Mild Steel under Sharply Concentrated Stress

1953 ◽  
Vol 19 (87) ◽  
pp. 14-18
Author(s):  
Fujio NAKANISHI ◽  
Minoru HANADA ◽  
/ /
Keyword(s):  
Mild Steel ◽  
Yield Point

113 Yield-point Phenomena of Non-uniformly Annealed Mild Steel under Uniaxial Tension

2006 ◽  
Vol 2006.44 (0) ◽  
pp. 25-26
Author(s):  
Gakuto SAKAI ◽  
Yoshitaka GOTO ◽  
Fusahito YOSHIDA
Keyword(s):  
Mild Steel ◽  
Uniaxial Tension ◽  
Yield Point

scholarly journals A stress-strain curve for the atomic lattice of mild steel in compression

1942 ◽  
Vol 181 (984) ◽  
pp. 72-83 ◽  
Keyword(s):  
Mild Steel ◽  
Yield Point ◽  
Applied Stress ◽  
Pure Iron ◽  
Lattice Strain ◽  
Strain Curve ◽  
Partial Recovery ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Atomic Lattice

A stress-strain curve has been obtained for the atomic lattice of mild steel subjected to compression. A set of atomic planes is selected of which the spacing is practically perpendicular to the direction of the stress, and the change in spacing is measured as the magnitude of the applied stress is systematically varied. The behaviour of the lattice is compared with the corresponding stress-strain relation for the external dimensions in the compression test, and also with the lattice stress-strain curve previously obtained for the same material when subjected to tensile stress. Other experiments are described on the behaviour of the lattice of pure iron in compression. It had been previously shown that at the external yield in tension, the atomic spacing exhibited an abrupt change which remained indefinitely on removal of the stress; the effect was interpreted as a lattice yield point. The present work establishes that the lattice possesses a yield point also in compression, again marking the onset of a permanent lattice strain. The direction of this strain, however, is opposite to that found in tension, and the magnitude increases systematically with the applied stress. The experiments on the pure iron show that under extreme deformation the permanent lattice strain tends to a limit and that with continued deformation partial recovery from the strain may occur. The results suggest that the mechanics of the metallic lattice involve the principle that, after the lattice yield point, in a given direction the lattice systematically assumes a permanent strain in such a sense as to oppose the elastic strain induced by the applied stress.

The Development of a Machine for High-Speed Testing of Materials

1937 ◽  
Vol 135 (1) ◽  
pp. 467-483
Author(s):  
R. J. Lean ◽  
H. Quinney
Keyword(s):  
Mild Steel ◽  
Yield Point ◽  
High Speed ◽  
Testing Machine ◽  
Strain Curve ◽  
Maximum Point ◽  
Variable Speed ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
High Speed Machine

The paper contains an account of a research into the effect on metals of different speeds of fracture, using a specially designed high-speed testing machine which is described in detail. The experiments were conducted both in this machine and in a 5-ton variable-speed autographic tensile machine, on five steels, the rate of loading being varied for each. With the high-speed machine toughness, ductility, time to produce fracture, and the stress-strain curve were obtained. The results of these combined tests, given in tables and graphs, show that there is a marked increase in stress due to higher speed of testing; and also that the work required to cause fracture increases with the speed. For mild steel the stress at the initial yield point was found to be in excess of that at the maximum point, when the speed of testing was increased the ductility did not appear to suffer.

scholarly journals A new attack upon the problem of fatigue of metals, using X-ray methods of precision

1936 ◽  
Vol 154 (883) ◽  
pp. 510-539 ◽  
Keyword(s):  
Tensile Stress ◽  
Mild Steel ◽  
Yield Point ◽  
Systematic Study ◽  
Fatigue Tests ◽  
X Ray Diffraction ◽  
X Ray ◽  
Static Tensile ◽  
Static Yield ◽  
Ray Methods

The failure of metals by fatigue has been investigated by applying precise methods of X-ray diffraction to a systematic study of the changes produced in the crystalline structure under various conditions of test. The material used for the experiments was a normalized mild steel (0*1% C). The fatigue tests were of three distinct types involving, respectively, ( a ) cycles of reversed torsional stressed, ( b ) cycles of reversed direct stresses, and ( c ) cycles of alternating direct stresses where the superior stress of the cycle was maintained at a constant value of tensile stress exceeding the static yield point of the material. In addition, comparable observations have been made of the changes in structure arising from the application of static tensile and static torsional stresses of various intensities including those causing fracture.

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