Hot working of aluminum alloy 7075
Large deformation, constant true strain rate, isothermal compression tests have been conducted on the aluminum alloy 7075 at strain rates which ranged from 103 to 1 sec1 and temperatures which spanned the practical forging temperature range of 3250C 4250 C. In this strain rate and temperature regime the stress-strain curves show very little strain hardening or softening, and the relationship between the (visco) plastic strain rate iP, the absolute temperature T, and the flow stress a can be represented well by the classical one-dimensional equation:
A comparison study on forming limit prediction methods for hot stamping of 7075 aluminum sheet
Abstract This paper provides an experimental and theoretical study of AA7075 hot forming limits. The limits were measured in a wide range of temperature and strain rates using Nakazima test. Elevated temperature tensile testing was performed to capture the constitutive behavior. Two flow models have been calibrated using the tensile data, the Misiolek model and a continuum damage mechanics (CDM) model. Two theoretical forming limit predictions methods have been investigated, the Marciniak–Kaczynski (M–K) method and a method based on CDM. In the M–K model, the constitutive behavior was modeled by the von Mises yield with the Misiolek flow model. The strain rate sensitivity of the groove section was taken into consideration. The CDM forming limit prediction method utilized the corresponding flow model and a simplified plane stress CDM model. Parameters in the constitutive models and the forming limit prediction models were expressed as functions of temperature and strain rate. Both methods accurately predicted the AA7075 forming limits in the hot stamping temperature range and strain rate range.
Capturing Crime in the Antipodes: Colonist Cultural Representation of Indigeneity
This chapter adopts a Southern criminological lens, which allows the authors to explore how colonialism has been constructed and depicted in museums within both regional and urban Australia. By studying spatial and historical silences in Australian museums, this chapter offers a consistent frame to chronologically chart Anglo-Australian depictions of Indigeneity, imperialism and violence wielded by the state. As this chapter will argue, museums can often reflect Westernized (white) conceptualizations about Indigeneity and the state violence involved in colonization, which actively re-enforces popular views and influences sociopolitical visions of identity, the state and justice.