Al-cu-mg Containing Ag Heat-resistant Aluminum Alloy, Thermal Simulation, Thermal Exposure And Creep Behavior

Constitutive equations and an artificial neural network (ANN) model were used for the analysis and simulation of the flow behavior during hot compression deformation of homogenized heat-resistant Al-Cu-Mg-Ag alloy. The effect of thermal exposure on the mechanical properties and microstructure of Al-Cu-Mg-Ag alloy was investigated using hardness test, mechanical properties test at room temperature, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Creep test was used for investigating the effect of aging treatment on the creep resistance and changes in microstructures of under-aged alloy. The constitutive equations of creep behavior were built to study creep mechanisms of the alloy. The results are as follows:1. True stress-strain curves of Al-Cu-Mg-Ag alloy during hot compression deformation have a characteristc of dynamic recrystallization. The curves can be described as four different stages, i.e., work hardening, transition, softening and steady stages. Its flow behavior can be described using the Arrhenius equation which is ameliorated by hyperbolic sine fuction and Z parameter, which is a fator of temperature-compensation strain rate.2. BP artificial neural network whose architecture became to be 3-20-1 was developed to predict the flow stress during hot compression deformation. Compare with stress-strain constitutive equation, BP artificial neural network has a higher correlation coefficient between predicted results and experimental results.3. When exposed at 150℃, its strengths of under-aged Al-Cu-Mg-Ag alloy increased firstly, and then decreased subsequently with the increasing of thermal exposure time. TheΩphase of under-aged Al-Cu-Mg-Ag alloy just grew up slightly. Theθ'phase coarsened gradually and increased in number. When exposed from 200℃to 300℃, its strengths decreased with prolonging the time or increasing the temperature, which had a contrary trend of elongation. When exposed at 300℃for 100 h, most of theΩphase andθ'phase almost turned into equilibrium phaseθ. The width of the PFZ increased further.4. Secondary precipitation was observed in the creep sample of under-aged Al-Cu-Mg-Ag alloy, which had better high-temperature creep resistance. Creep constitutive equation can be used to describe the relationships among steady-state creep rate, creep temperature and creep stress:ε= 7.6×10-4σ3.59835 exp(-102000/RT)...