A review of dynamic recrystallization phenomena in metallic materials

Recent advances in ageing of 7xxx series aluminum alloys: A physical metallurgy perspective

A review on forming techniques for manufacturing lightweight complex—shaped aluminium panel components

An FE model of the solution heat treatment, forming and in-die quenching (HFQ) process was developed. Good correlation with a deviation of less than 5% was achieved between the thickness distribution of the simulated and experimentally formed parts, verifying the model. Subsequently, the model was able to provide a more detailed understanding of the HFQ process, and was used to study the effects of forming temperature and speed on the thickness distribution of the HFQ formed part. It was found that a higher forming speed is beneficial for HFQ forming, as it led to less thinning and improved thickness homogeneity.

https://research.birmingham.ac.uk/portal/files/18356863/Dean_Numerical_Study_Solution_Heat_Treatment_International_Journal_Machine_Tools_Manufacture_2014.pdf

Numerical study of the solution heat treatment, forming, and in-die quenching (HFQ) process on AA5754

High temperature tensile and electron backscatter diffraction (EBSD) techniques were combined to perform a systematic investigation for the hot deformation behavior and microstructure evolution of the Ti55 alloy Under temperatures ranging from 885 to 935 °C and stain rates of 83×10−4 s−1−133×10−2 s−1, all the flow curves of the Ti55 alloy exhibit similar behaviors: after reaching the peak flow stress, the curves enter into a softening stage and then remain a steady level, where the maximum superplastic elongation of 987% indicates good superplasticity Detailed microstructure characterizations under different deformation stages show that the grain aspect ratios decrease greatly and the fractions of high angle boundaries (>15°) increase rapidly at the softening stage These observations are attributed to the dynamic recrystallization, in which low angle grain boundaries (

High-temperature tensile deformation behavior and microstructure evolution of Ti55 titanium alloy

A non-isothermal ageing (NIA) process was proposed for an Al–Zn–Mg–Cu alloy aiming to accommodate heating and/or cooling procedures in large components. The precipitation was investigated systematically via TEM observation and DSC analysis. The age-hardening and the conductivity variation were examined to evaluate the potential in the strength and the corrosion resistance, respectively. Double cantilever beams (DCB) experiments were carried out to evaluate the stress corrosion cracking (SCC) resistance. A secondary precipitation occurs during the cooling procedure of the NIA process, which leads to an increase in the precipitates number density and thus induces an extra hardening. The secondary precipitation also contributes to the increase of conductivity of the alloy in the most part of the cooling procedure, but leads to a slight decrease at the terminal stage. The alloy׳s resistance to SCC improves persistently as the NIA proceeds. The evolution in microchemistry in grain boundary and adjacent regions is supposed to contribute to the improvement of corrosion resistance. The current study suggests that the NIA process (40 °C→190 °C→100 °C, 20 °C/h) is capable of enduing higher mechanical performances and comparable corrosion resistance to Al–Zn–Mg–Cu alloys, as compared with that of the T74 condition, which can be technically significant for ageing treatment of large components.

Ageing behavior and stress corrosion cracking resistance of a non-isothermally aged Al–Zn–Mg–Cu alloy

The deformation behavior of Ti–22Al–25Nb alloy at elevated temperatures and different stain rates was investigated using uniaxial tensile test. It was found that the tension was accompanied with the effect of hardening and softening, under which the stress–strain curve was characterized by a rise to a peak followed by a nearly linear drop in flow stress. The peak stress was strongly dependent on the temperature and strain rate. The underlying mechanism was clarified in terms of dislocation dynamics. Work hardening and strain rate hardening both contributed to the hardening mechanism, and the softening mode was dominated by dynamic recovery. The effect of work hardening was completely neutralized by dynamic recovery. Owing to the strain rate hardening, the alloy exhibited certain degree of superplasticity. The further drop in flow stress after the peak was due to the rise in temperature, which originated from the heat generated during deformation. The deformation mechanism was dominated by dislocation slip and climb. The misorientation distribution between β/B2 and α2 phase scarcely changed, implying a harmonious deformation of the two phases.

Tensile deformation behavior of Ti–22Al–25Nb alloy at elevated temperatures

As important light-weight structure material, aluminum alloy has been widely used in automotive and aerospace industries, in which the manufacturing of parts with high strength and good dimensional accuracy has been the main task. In this paper, special device was developed to investigate the hot forming–quenching integrated process of cold-rolled 6A02 aluminum alloy sheet. Strengthening effect was reflected by Vickers hardness measuring and uniaxial tensile test. Microstructure examination was conducted to clarify the strengthening mechanism by scanning electron microscope (SEM), transmission electron microscopy(TEM) and electron backscattering diffraction (EBSD). Results show that Vickers hardness increases with solution time (

Experimental investigation on hot forming–quenching integrated process of 6A02 aluminum alloy sheet

New manufacturing technology for light-weight structure materials has been used to meet the requirements for weight reduction and safety performance. In this paper, the hot forming-quenching integrated process of 6A02 aluminum alloy sheet at different forming-dies temperatures ranging from 50 °C to 350 °C was investigated. Vickers hardness test and uniaxial tensile test were carried out to reveal the strengthening behavior. Microstructure evolution was observed to clarify the strengthening mechanism with electron backscattering diffraction (EBSD), transmission electron microscopy (TEM) and scanning electron microscope (SEM) methods. Results show that the Vickers hardness and tensile strength decreased with increasing forming-dies temperature. No obvious decrease in strength appeared until the forming-dies temperature reached 250 °C. The corresponding Vickers hardness was increased to 100.6 HV from original 73 HV in rolled condition, and the tensile and yield strengths were 303.8 MPa and 257.1 MPa, respectively. When the temperature of forming-dies rose to 350 °C, the tensile and yield strengths dropped to 270.1 MPa and 213.7 MPa, respectively. The strengthening phase in Al matrix was the dispersed needle-shaped β″ precipitates with size about 10−50 nm. Transformation of the rod-shaped β′ precipitates with 150–300 nm in size at the grain boundaries and in grain interiors led to the decrease in strength. The forming-dies temperature should not be higher than 250 °C for the integrated forming of 6A02 aluminum alloy sheet to obtain enough strengthening effect.

Shijian Yuan

Papers

Ageing behavior and stress corrosion cracking resistance of a non-isothermally aged Al–Zn–Mg–Cu alloy

Tensile deformation behavior of Ti–22Al–25Nb alloy at elevated temperatures

Experimental investigation on hot forming–quenching integrated process of 6A02 aluminum alloy sheet

Investigation on strengthening of 6A02 aluminum alloy sheet in hot forming-quenching integrated process with warm forming-dies

Formability and strengthening mechanism of solution treated Al–Mg–Si alloy sheet under hot stamping conditions