Damage in Creep Aging Process of an Al-Zn-Mg-Cu Alloy: Experiments and Modeling

Abstract

In creep age forming (CAF), large integral panel components of high-strength aluminum alloy can be shaped and strengthened under external elastic loading at an elevated temperature through creep deformation and age hardening, simultaneously. However, the high ribbed structure on panel may induce stress concentration, inhomogeneous plastic deformation and even damage evolution on the bending rib, leading to the difficulty in controlling forming precision and material properties. Therefore, the generation and evolution of damage are necessary to be considered in the design of CAF. Taking 7050 aluminum alloy as the case material, the continuous and interrupted creep aging tests at 165 • C and three stress levels (300, 325, and 350 MPa) were conducted, and the corresponding material properties, precipitate, and damage microstructures were studied by mechanical properties tests, transmission electron microscope (TEM) and scanning electron microscope (SEM) characterizations. With the increase of stress level, the creep deformation occurs easier, the precipitates grow up faster, the creep damage occurs earlier, the growth rate and the size of microvoids increase, the mechanical properties decrease more rapidly, and the dominant mechanism of creep fracture changes from shear to microvoid coalescence. To simulate creep aging behavior with damage, a continuum damage mechanics (CDM) based model is calibrated and numerically implemented into ABAQUS solver via CREEP subroutine. The CAF of 7050 aluminum alloy panels with different height ribs were conducted by experiment and FE simulation. The forming process presents a typical stress relaxation phenomenon. The creep damage mainly occurs on the bending rib due to the severe stress concentration. With the increase of rib height, the creep strain and damage degree increase, but the springback decreases.

Creep Analysis of Rotating Thick Cylinders Subjected to External and Internal Pressure: Analytical and Numerical Approach

“…The cylinder under consideration for creep behavior investigation is assumed to be composed of monolithic material in different studies [17][18][19][20][21]. Mostly, aluminum or its alloys are used in many engineering applications to save power from their lightweight nature, but they are susceptible to creep, which may obstruct their use in large-scale applications [22][23][24].…”

Research on Creep Test of Compacted Graphite Cast Iron and Parameter Identification of Constitutive Model under Wide Range of Temperature and Stress

“…Sci. 2022, 12, 5032 2 of 12 At present, many scholars have carried out much work on the creep behavior of commonly used materials [13][14][15][16][17]. However, most of them have only carried out creep tests under a small temperature and stress range.…”