Evaluation of a 7050-TAF aluminum alloy submitted to creep age forming

Abstract

CAF process combines creep and precipitation hardening which are highly dependent on time and temperature. The aging cycle relax the stresses induced during the loading phase. At the end of the process stress relaxation induces shape changes in the part but significant spring back is observed (about 70%). Usually CAF cycles for 7XXX alloys use times around 20 h and temperatures in the range of 120°C to 190°C. In the present work CAF tests were performed using the alloy 7050 in an intermediate condition named Temper to Age Forming (TAF). Using the alloy 7050-TAF resulted in significant process time reduction. From TAF temper, only 8 hours are necessary to achieve properties comparable to T74. Coupons were submitted to CAF in two levels of initial stress, 190 MPa and 290 MPa, resulting in spring back values of 70% and 60 % respectively. In addition, constant load creep tests were performed in the same stress levels and time of CAF tests to find the creep strain values. Creep tests performed under 190 MPa resulted in strain values around 0,1% after 8 h. On the other hand creep tests performed under 290 MPa failed after 7 h with creep strain values of 1,7%. Results obtained are close to that found in previous studies and it is possible to conclude that the use of alloy 7050 in TAF condition allows CAF to be done in 8 hours, since the initial stress is lower than 290 MPa.

On the Use of Special Functions for Analyzing the Steady State Creep in Short Fiber Composites Semi-theoretically

“…To analyze the steady state creep problem, a cylindrical unit cell model is assumed in accordance with previous researches in order for modeling a short fiber composite 1,2,[7][8][9][10][11] . Therefore, a unit cell of the short fiber composite is a representative for a complete composite.…”

“…In the recent years, the analytical methods have been introduced for analyzing nonlinear differential and ordinary equations with purpose of obtaining suitable solutions and algorithms. In addition, some analytical and experimental attempts were carried out to analyze the creep behaviors [7][8][9][10][11][12] .…”

Material characterization of EN AC-Al Si12CuNiMg alloy in stress relaxation and creep conditions

“…Stress relaxation is a mechanical behavior in which the material produces a certain strain at a specific temperature and initial stress. This phenomenon usually occurs when a material is subjected to elevated temperatures for a prolonged duration at constant strain [9]. During the experimental investigation, the temperature and total strain of the material are kept constant while the stress gradually decreases over time.…”

Neural Network Based Simulation of Micro Creeping Fibrous Composites SiC/Al6061 for Plastic Behaviour

“…In addition, recently as a different research work, creep tests have been fulfilled at 923 and 973 K on two heats with different solution annealing conditions [18]. Moreover, in the recent years, various investigations and experimental attempts were carried out to analyze the creep behaviours of the materials [19][20][21][22][23][24]. For example, Monfared [24] predicted stress behaviour in short fiber composites, under axial tensile stress, based on well-behaved displacement rates in…”