Dynamic hardening equation of the auto-body steel sheet with the variation of temperature

Abstract

This paper is concerned with the empirical hardening equation of steel sheets for an auto-body at intermediate strain rates with the variation of temperature. In order to identify the temperature dependence of the strain-rate sensitivity of steel sheets such as SPRC35R, SPRC45E and TRIP60, uniaxial tensile tests have been performed with the variation of the strain rate from 0.001/sec to 200/sec and the environmental temperature from -40 o C to 200 o C. The thermo-mechanical response at the quasi-static state is obtained from static tensile tests and that at the intermediate strain rate is obtained from high speed tensile tests. The effects of both the strain rate and the temperature on the flow stress and the fracture elongation are investigated with the experimental data. Experimental results provide the variation of the strain-rate sensitivity with respect to the temperature. They also show that as the strain rate increases, the variation of flow stress becomes sensitive to the temperature. A phenomenological constitutive model is newly proposed by modifying the well-known Khan-Huang-Liang model. Based on the experimental data, both the strain rate and the temperature dependent sensitivity of the flow stress are considered in the proposed model by coupling the strain, the strain rate and the temperature. In order to verify the accuracy of the proposed model quantitatively, the standard error between the experimental data and the fitted one is compared with other empirical constitutive models such as the Johnson-Cook and the Khan-Huang-Liang models. The comparison demonstrates that the model proposed gives relatively accurate description of the experimental data at the various strain rates and temperatures.

Effects of Microstructure on the Strain Rate Sensitivity of Advanced Steels

“…The shape of the stress-strain curve is also different at high strain rate; the material exhibits lower strain hardening at 500 s -1 . This is a typical behavior of mild steels and several researchers have reported the same behavior in previous studies [7,11,19]. Positive strain rate sensitivity is also observed in the austenitic stainless steel 201, with a significant increase in the yield strength.…”

“…Strain rate effects on the mechanical properties of steels have been studied by many researchers over the past decade; examples include these references [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. However, the majority of these studies did not focus on the microstructure and the role it plays in dictating the strain rate sensitivity of the steel grade [3][4][5][6][7][8][9][10][11][12][13][14]. Few studies considered the microstructure and its correlation to rate sensitivity, particularly in advanced steel grades.…”

Evaluation of the effect of the strain rate on the tensile properties of carbon–epoxy composite laminates

“…The gripping system of HSMTM grabs the specimen when its speed reaches a designated constant velocity. 20…”

Determining Johnson-Cook Constitutive Equation for Low-Carbon Steel via Taylor Anvil Test

“…Numerous dynamic hardening material models have been developed to characterise the stress-strain relations for various materials at varying temperatures and strain rates. Among the most popular dynamic hardening material models are the Johnson-Cook model [14], the modified Johnson-Cook model [15], Khan-Huang model [16], modified Khan-Huang model [17], Zerilli-Armstrong model [18], or Preston-Tonks-Wallace (PTW) model [19].…”