Assessment of the Influence of Surface Hardening on Fatigue Limit by Residual Stresses*

Pavlov, V. F.; Кирпичeв, Виктор Алексеевич; Vakulyuk, V. S.; Сазанов, В. П.; Букатый, А. С.

doi:10.1007/s11223-014-9596-9

Cited by 4 publications

(2 citation statements)

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“…An effective way to change the composition of the stamping tool's surface layer, providing the necessary set of properties of its working surface, is chemical-thermal treatment. As a result, the structure and properties of the surface layer change, the strength, wear, and heat resistance of steel increases during the heating process by forming stable carbides, nitrides, and borides [12].…”

Section: Methodsmentioning

confidence: 99%

Carbonitration of a Tool for Pressing Stainless Steel Pipes

Иванов

Mohylenets²,

Dumenko³

et al. 2020

JES

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To upgrade the operational stability of the tool at LLC “Karbaz”, Sumy, Ukraine, carbonation of tools and samples for research in melts of salts of cyanates and carbonates of alkali metals at 570–580 °C was carried out to obtain a layer thickness of 0.15–0.25 mm and a hardness of 1000–1150 НV. Tests of the tool in real operating conditions were carried out at the press station at LLC “VO Oscar”, Dnipro, Ukraine. The purpose of the test is to evaluate the feasibility of carbonitriding of thermo-strengthened matrix rings and needle-mandrels to improve their stability, hardness, heat resistance, and endurance. If the stability of matrix rings after conventional heat setting varies around 4–6 presses, the rings additionally subjected to chemical-thermal treatment (carbonitration) demonstrated the stability of 7–9 presses due to higher hardness, heat resistance, the formation of a special structure on the surface due to carbonitration in salt melts cyanates and carbonates. Nitrogen and carbon present in the carbonitrided layer slowed down the processes of transformation of solid solutions and coagulation of carbonitride phases. The high hardness of the carbonitrified layer is maintained up to temperatures above 650 °C. If the stability of the needle-mandrels after conventional heat treatment varies between 50–80 presses, the needles, additionally subjected to chemical-thermal treatment (carbonitration) showed the stability of 100–130 presses due to higher hardness, wear resistance, heat resistance, the formation of a special surface structure due to carbonitration in melts of salts of cyanates and carbonates. Keywords: needle-mandrel, matrix ring, pressing, heat treatment, carbonitration.

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Section: Methodsmentioning

confidence: 99%

Carbonitration of a Tool for Pressing Stainless Steel Pipes

Иванов

Mohylenets²,

Dumenko³

et al. 2020

JES

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“…[7], studied the residual stresses in metal structures and proposed calculation methods for determining residual stresses. The direct effect of residual stresses on improving fatigue characteristics was studied in [8][9][10][11][12][13]. Particular attention to the influence of residual stresses on the reliability of pipelines is given in [14][15].…”

Section: Introductionmentioning

confidence: 99%

Use of Magnetic Anisotropy Method for Assessing Residual Stresses in Metal Structures

Krivokrysenko

Popov

Bolobov

et al. 2020

KEM

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A series of experiments on measuring of difference between the main mechanical stresses (DPMS) was carried out using a mechanical stress scanner based on the magnetoanisotropic method. The magnitude of the DPMS is fixed when a magnetic field is induced on a carbon steel plate under uniaxial tension. A direct proportional relationship is shown between the magnitude of the DPMS signal recorded by the scanner and the magnitude of tensile stresses in the plate in the region of elastic deformation of steel. Measurement of the DPMS signal in the central part of similar plates previously subjected to elastic-plastic bending showed that positive values of the signal are fixed in the surface layers of the metal on the inside of the plate, which corresponds to tensile residual stresses, while the negative ones concentrate at the external surface, which corresponds to compressive stresses. A transverse incision on a curved plate from the inside leads to a decrease in the value of the signal of the DPMS, which indicates a decrease in the level of residual stresses in the metal. The values of the DPMS signal in the central part of the curved plate, recalculated using the established calibration dependence on the value of the residual stresses, were compared with the values of the stresses established by calculation, based on the Henki’s theorem on the unloading of an elastic-plastic body. A satisfactory convergence was obtained between the experimental and calculated data.

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