Effects of Temperature and Strain Rate on the Fracture Behaviors of an Al-Zn-Mg-Cu Alloy

Abstract

Effects of temperature and strain rate on the fracture behaviors of an Al-Zn-Mg-Cu alloy are investigated by isothermal uniaxial tensile experiments at a wide range of temperatures and strain rates, from room temperature (RT) to 400 °C and from 10−4 s−1 to 10−1 s–1, respectively. Generally, the elevation of temperature leads to the increasing of elongation to fracture and the reduction of peak stress, while higher strain rate results in the decreasing of elongation to fracture and the increasing of peak stress. Interestingly, we found that the coefficient of strain rate sensitivity (m-value) considerably rises at 200 °C and work of fracture (Wf) fluctuates drastically with the increase of strain rate at RT and 100 °C, both of which signify a non-uniform and unstable deformation state below 200 °C. A competition of work hardening (WH) and dynamic recrystallization (DRX) exists at 200 °C, making it serve as a transitional temperature. Below 200 °C, WH is the main deformation mechanism of flow stress, and DRX dominates the flow stress above 200 °C. It has been found that from RT to 200 °C, the main feature of microstructure is the generation of dimples and microvoids. Above 200 °C, the coalescence of dimples and microvoids mainly leads to the failure of specimen, while the phenomenon of typically equiaxed dimples and nucleation appear at 400 °C. The observations of microstructure are perfectly consistent with the related macroscopic results. The present work is able to provide a comprehensive understanding of flow stress of an Al-Zn-Mg-Cu alloy at a wide range of temperatures and strain rates, which will offer valuable information to the optimization of the hot forming process and structural design of the studied alloy.

Effect of Zinc on the Tensile Properties, Microstructure and characteristics in Aluminum Alloys

“…The obtained demeanors were described using draw an analogy. A ponderous peak for Aluminum rich phase was constructed to be slightly diminutive with the extension of Zinc for Zinc-60Aluminum but more for Zinc-90Aluminum; EDX, present consequences were in agreement see table (1). A ponderous peak for Aluminum-Zinc was found to be slightly decreased with the supplement of Aluminum, strain for Zinc-40 Aluminum, is higher than that of second alloy by 12%.…”

“…Zinc-Aluminum is the valuable material because of the toughness, subsequently, they applied in the ship, the factories, and cars texture because of the density and strength overwhelming conductance abrasion [1]. The introduction of Zinc element can forceful development its intensity at 298 K. Nevertheless a large component of samples were with each other impair warm operability of samples [2].…”

Effect of Hot Deformation and Heat Treatment on the Microstructure and Properties of Spray-Formed Al-Zn-Mg-Cu Alloys

“…The high-temperature performance of the 7075-T6 alloy under different strain rates from room temperature to 450 • C was studied by Rong et al [147], who sought to propose an improved continuous fracture model to describe and predict the fracture behavior of the 7075 alloy at high temperatures. It was found by Guo et al [148] that concurrent work hardening, dynamic recovery, and dynamic recrystallization at 200 • C were exhibited by the hot-rolled Al-Zn-Mg-Cu alloy; below 200 • C, work hardening emerged as the primary deformation mechanism, while above 200 • C, dynamic recovery and dynamic recrystallization became the main deformation mechanisms, and the microstructure became sensitive to the flow strain rate. A decrease in the flow stress of 7150 during isothermal hot compression within the temperature range of 325-425 • C and a strain rate range of 0.01 −1 s −1 was observed by Jiang et al [149].…”