Change of Specimen Temperature during the Monotonic Tensile Test and Correlation between the Yield Strength and Thermoelasto-Plastic Limit Stress on the Example of Aluminum Alloys

Abstract

This paper presents an attempt to generalize the description of the course of specimen temperature changes during the tensile test and to connect the value of the thermoelasto-plastic limit stress with the value of a clear (physical) or proof strength (offset yield strength) on the example of tests of the following aluminum alloy sheets used in Poland for airplane structures: 2024-T3 and D16 in three grades: D16ATV, D16CzATV, and D16UTV. A thermographic camera was used for specimen surface temperature measurement during the tensile test. The Portevine–Le Chatelier effect (the so-called PLC effect) was observed for tests of specimens cut from sheet plates, which was strongly reflected in the temperature fluctuations. The course of temperature change during tensile tests was divided into four characteristic stages related to the occurrence of a clear or offset yield strength. It was found that if there is a clear yield strength, the value of the thermoelasto-plastic limit stress was greater than this yield strength. If there was an offset yield strength, the value of the thermoelasto-plastic limit stress was lower than this yield strength. The differences in the aforementioned values of individual yield strengths did not exceed several percent. Thus, it can be concluded that the thermoelasto-plastic limit stress determined on the basis of the course of specimen temperature changes during the tensile test is well correlated with the value of the yield strength of the material.

An experimental electro-thermo-mechanical characterization of plastic deformation of quenched and tempered pipe steel for oil country tubular goods

“…The temperature in all samples decreased in the elastic zone and an increased during plastic deformation. The results are in agreement with results reported by Lipski et al [19]. The specific heat capacity of the investigated OCTG pipe steel was experimentally determined to a value of 0.5 kJ/°C and subsequently the density of the pipe steel was measured to be 7900 kg/m 3 .…”

“…These results are in agreement with results obtained by Choung et al [20] respectively. The thermo elastic-plastic characterization of OCTG pipe steel based on the strain-temperature measurement during the tensile test done in this study is well correlated with those reported by Lipski et al [19]. The results can be used for constitutive material modelling and numerical simulation of OCTG pipe connections.…”

On the correlation of temperature harmonic content with energy dissipation in C45 steel samples under fatigue loading

“…In the present work there is only a limited increase of mean temperature T o (see Figs. 13,14). This is likely due to the gradual decrease of loading frequency with the applied stress amplitude.…”