Constants for hot deformation constitutive models for recent experimental data

Abstract

This paper presents previously unavailable constants for the Sellars and Tegart constitutive model for hot metalworking. The materials considered are aluminium alloys 2024, 5083, 6061, 7050, 7075 and 356, carbon steel 1018, stainless steel 304, titanium alloy 6Al-4V, and magnesium alloys AZ31 and AZ61. These materials and their mechanical properties at high temperature are of great interest for latest generation manufacturing processes involving deformation to accomplish solid state joining, such as friction stir welding, cold spray and magnetic impulse welding. The results are also useful to model established processes, such as hot rolling, forging and creep. The methodology used to obtain the constants consists on non-linear regressions based on partial data sets as it was conducted previously. The input data were obtained from published values for hot compression experiments. All regressions presented here have a coefficient of determination R 2 .0?95. When possible, the results obtained were compared to previous published regressions.

Thermo-mechanical and metallurgical aspects in friction stir processing of AZ31 Mg alloy—A numerical and experimental investigation

“…where R = 53.3 MPa,˛= 7.78 × 10 8 s −1 and m = 4.36 are material constants that are based on a regression analysis of experimental mechanical testing data based on hot extrusion tests for AZ31 Mg (Tello et al, 2010). The mechanical tests were conducted at temperature range between 366 K and 750 K, while strain rates were between 0.00083 s −1 and 0.083 s −1 .…”

“…Typical values of Q = 129 KJ/mol and R = 8.314 J/mol K are used in this work for AZ31 Mg (Tello et al, 2010).…”

Determining a Flow Stress Model for High Temperature Deformation of Ti-6Al-4V

“…Graph to show the difference between the stress strain curves generated at 1100°C for the flow stress models given by Sheppard et al [2], Tello et al [4] and Braga et al [3] for the flow stress model created in this study…”

Simulation of Material Flow and Heat Evolution in Friction Stir Processing Incorporating Melting

“…where o-Ä = 53.3Mpa, /I = 7.78 x lO** s"', and n = 4.36 are material constants for AZ31B Mg [30] and Z is the Zener Hollomon parameter given by Z = éexp{Q/RT) (12) where /? = 8.314 Jmol 'K ' is the gas constant and 2=129 kJ moP' is the activation energy for hot deformation of AZ31B Mg [30].…”

“…= 8.314 Jmol 'K ' is the gas constant and 2=129 kJ moP' is the activation energy for hot deformation of AZ31B Mg [30]. Viscosity of the solid can thus be introduced as a function of temperature and effective strain rate by substituting Eqs.…”