Effect of changes in the elastic characteristics of plastically strained materials on residual stresses

Abstract Future development of thermal spray processes and new composite materials raises an important problem concerning the transition from qualitative to quantitative methods of coatings evaluation. It is well known that thermal spray coating deposition in most cases is accompanied by the formation of temporal and residual stresses through the coating thickness. For proper evaluation of formed stressed state it is extremely important to know the real value of elastic characteristics in different layers of the coating. This problem has become more complicated taking into consideration the variety of materials, different spray parameters, number of coating layers and extreme service conditions. These values can be obtained only from experimentation. Elastic characteristics (EC) could be used in many calculations, such as durability, stiffness, fatigue, vibration and others. This paper describes new methods of experimental determination of elastic characteristics presumed as variable throughout the coating thickness. Influence of coating composition, particle size of initial powders, spray parameters, post-treatment and other factors on elastic modulusses were studied. Obtained experimental data for different materials supplement existing data and can be used for evaluation of residual stresses and other purposes.

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Methods of Determination and Control of Residual Stresses in Plasma Spray Coatings

Thermal Spray 1997: Proceedings from the United Thermal Spray Conference ◽

10.31399/asm.cp.itsc1997p0867 ◽

1997 ◽

Author(s):

L. Dekhtyar ◽

A. Kleyman ◽

V. Andreychuk ◽

S. Berman

Keyword(s):

Residual Stresses ◽

Thermal Spray ◽

Plasma Spray ◽

Thermal Spraying ◽

Thermal Spray Coatings ◽

Coating Deposition ◽

Spray Coatings ◽

Plasma Spray Coatings ◽

And Control ◽

Elastic Characteristics

Abstract Residual stresses exert profound influence on the longevity of parts with thermal spray coatings. The distribution and value of the residual stresses depend on method of coating deposition, composition of the applied material, parameters of thermal spraying and methods of post-treatment. Therefore, the study of the influence of the various technological factors on the residual stresses in the plasma spray coatings is very important. Due to heterogeneity of the coating, residual stresses can be determined only by the experimentation by using new methods which take into consideration real values of elastic characteristics and density of elementary layers. Methods and formulas for the calculations of the residual stresses in coatings deposited on bars, rings, discs, cylinders are presented. Experimental results for the various thermal spray coatings are also shown. These results can be used for the optimization of coating deposition and would supplement the existing database.

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Method to evaluate residual stresses in the laser cutting process

Lasers in Engineering ◽

10.1080/08981500290022752 ◽

2002 ◽

Vol 12 (1) ◽

pp. 27-41 ◽

Cited By ~ 7

Author(s):

Y. Zamachtchikov ◽

F. Breaban ◽

P. Vantomme ◽

A. Deffontaine

Keyword(s):

Residual Stresses ◽

Laser Cutting ◽

Cutting Process

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Prediction of residual stresses and springback after bending of a textured aluminium plate

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:20030185 ◽

2003 ◽

Vol 105 ◽

pp. 175-182 ◽

Cited By ~ 2

Author(s):

L. Delannay ◽

R. E. Logé ◽

Y. Chastel ◽

P. Van Houtte

Keyword(s):

Residual Stresses

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Theoretical study of the prestressing strand's stress by computer modeling methods

Ferrous Metallurgy Bulletin of Scientific Technical and Economic Information ◽

10.32339/0135-5910-2020-111-1139-1148 ◽

2020 ◽

Vol 76 (11) ◽

pp. 1139-1148

Author(s):

A. G. Korchunov ◽

E. M. Medvedeva ◽

E. M. Golubchik

Keyword(s):

Residual Stresses ◽

High Strength ◽

Pearlitic Steel ◽

Internal Stresses ◽

Steel Microstructure ◽

Compressive Stresses ◽

Wide Range ◽

Prestressing Strands ◽

Increasing Temperature ◽

Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

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