Martensitic Transformation and Mechanical Properties of Fe-added Au-Cu-Al Shape Memory Alloy with Various Heat Treatment Conditions

2014 ◽  
Vol 1760 ◽  
Author(s):  
Akira Umise ◽  
Masaki Tahara ◽  
Kenji Goto ◽  
Tomonari Inamura ◽  
Hideki Hosoda
Keyword(s):  
Heat Treatment ◽  
Cold Rolling ◽  
Shape Memory ◽  
Yield Stress ◽  
Mechanical Treatment ◽  
Tensile Tests ◽  
Treatment Temperature ◽  
Shape Memory Properties ◽  
Cold Rolled ◽  
Thermo Mechanical Treatment

ABSTRACTIn order to improve shape memory properties of Au-Cu-Al based shape memory alloys, the possibility to utilize thermo-mechanical treatment was investigated in this study, and effects of heat-treatment temperature on microstructure, martensitic transformation and mechanical properties of cold-rolled Au-30Cu-18Al-2Fe (AuCuAlFe) alloy were clarified by X-ray diffraction analysis (XRD, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile tests at room temperature (RT). Here, Fe addition to AuCuAl improves ductility. Cold rolling with the thickness reduction of 30% was successfully carried out in AuCuAlFe at RT. An exothermic heat was observed in DSC at temperature from 402K, suggesting that recovery started at 402K. Besides, the transformation temperature hysteresis increased by the cold-rolling. The alloy was completely recrystallized after the heat treatment at 573K for 3.6ks. Tensile tests revealed that the yield stress was raised by cold rolling and largely by the subsequent heat treatment at 433K, which corresponded to the recovery start temperature by DSC. The yield stress decreased with increasing heat treatment temperature over 453K, probably due to recrystallization. AuCuAlFe cold-rolled and subsequent heat-treated at 573K exhibited the lowest yield stress as well as stress-plateau region, indicating that the thermo-mechanical treatment is effective to improve shape memory properties of Au-Cu-Al based alloys.

Effect of Thermo-Mechanical Heat Treatment on Microstructure and Mechanical Property of 2197 Al-Li Alloy

2011 ◽  
Vol 284-286 ◽  
pp. 1621-1625 ◽  
Author(s):  
Bai Ping Mao ◽  
Jun Peng Li ◽  
Jian Shen
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Mechanical Treatment ◽  
Tensile Tests ◽  
Strengthening Effect ◽  
Precipitated Phase ◽  
Heat Treated ◽  
Peak Aged ◽  
Aged State ◽  
Thermo Mechanical Treatment

Effects of thermo-mechanical treatment on the mechanical properties and microstructure of 2197 alloy were studied through analyses of the mechanical properties by tensile tests and TEM observation of thermo-mechanical heat treated 2197 alloy plates of various states. Results show that the dominating precipitated phase of peak-aged 2197 alloy during thermo-mechanical heat treatment is T1 phase of which the size is 50~150nm. The precipitation and growth of T1 phase are accelerated due to the existed nucleation sites for heterogeneous nucleation of T1 phase offered by thermo-mechanical treatment, therefore, the time for 2197 alloy to reach the peak-aged state is shorten. The strength of 2197 alloy for peak-aged state is increased through thermo-mechanical treatment because the strengthening effect of T1 phase with higher aspect ratio is bigger than that of δ′ and θ′ phases.

scholarly journals Effect of Gradient Heat Treatment on Microstructure and Properties of Cu–Al–Mn Shape Memory Alloy

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2505
Author(s):  
Luohui Zhou ◽  
Jingling Lan ◽  
Jili Liu ◽  
Xu Li ◽  
Bowen Shi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Shape Memory ◽  
Optical Microscope ◽  
Mechanical Tests ◽  
Treatment Temperature ◽  
Microstructure Observation ◽  
Good Shape ◽  
Precipitated Phase ◽  
Dynamic Function ◽  
Shape Memory Properties

The columnar-grained Cu–Al–Mn shape memory alloys (SMAs), which have good shape memory properties and are prepared by a unidirectional solidification technique, were subjected to a gradient heat treatment under temperatures ranging from 100 to 450 °C. After this treatment, the microstructure, hardness, transformation temperature and shape memory properties of these samples could exhibit gradient changing trends, all of which were investigated by optical microscope, scanning electron microscopy (SEM), a Vickers microhardness tester, and a compression machine. The microstructure observation result shows that the acicular bainite-precipitated phase produces from scratch and then grows continuously with the increasing of the heat treatment temperature, finally presenting a graded distribution from one end section to another of the sample. The hardness tests give the samples results also increasing with temperature. Specifically, the change relationship between hardness and the treatment temperature mathematically satisfies dynamic function. In addition, it can be concluded from mechanical tests the compressive elastic–superelastic strain and strength of the samples show gradient variation features. Overall, our experimental investigation indicates that a gradient heat treatment is an effective way to conduct microstructure control or design for the Cu–Al–Mn SMAs, and their graded properties are mainly caused by the different fractions of the bainite phase producing in different local areas after the gradient heat treatment.

scholarly journals A thermo-mechanical machining method for improving the accuracy and stability of the geometric shape of long low-rigidity shafts

2021 ◽  
Author(s):  
Antoni Świć ◽  
Arkadiusz Gola ◽  
Łukasz Sobaszek ◽  
Natalia Šmidová
Keyword(s):  
Heat Treatment ◽  
Cross Section ◽  
Mechanical Treatment ◽  
Geometric Shape ◽  
Different Dimensions ◽  
Thermo Mechanical Treatment ◽  
Mechanical Machining ◽  
Simultaneous Heat ◽  
Accuracy And Stability

AbstractThe article presents a new thermo-mechanical machining method for the manufacture of long low-rigidity shafts which combines straightening and heat treatment operations. A fixture for thermo-mechanical treatment of long low-rigidity shafts was designed and used in tests which involved axial straightening of shafts combined with a quenching operation (performed to increase the corrosion resistance of the steel used as stock material). The study showed that an analysis of the initial deflections of semi-finished shafts of different dimensions and determination of the maximum corrective deflection in the device could be used as a basis for performing axial straightening of shaft workpieces with simultaneous heat treatment and correction of the initial deflection of the workpiece. The deflection is corrected by stretching the fibers of the stock material, at any cross-section of the shaft, up to the yield point and generating residual stresses symmetrical to the axis of the workpiece. These processes allow to increase the accuracy and stability of the geometric shape of the shaft.

Role of Deformation Twinning in Cold Rolling and Recrystallization of Titanium

2005 ◽  
Vol 495-497 ◽  
pp. 651-656 ◽  
Author(s):  
Y.B. Chun ◽  
S. Lee Semiatin ◽  
Sun Keun Hwang
Keyword(s):  
Heat Treatment ◽  
Cold Rolling ◽  
Texture Component ◽  
Recrystallization Texture ◽  
Rolling Texture ◽  
Mechanical Twinning ◽  
Treatment Temperature ◽  
Recrystallization Annealing ◽  
Cp Ti ◽  
Evolution Of Microstructure

The evolution of microstructure and texture during cold rolling and recrystallization annealing of commercial-purity Ti (CP-Ti) was established. Cold rolling to 40% reduction activated mechanical twinning- mostly > 3 2 11 < } 2 2 11 { compressive twins and > 1 1 10 < } 2 1 10 { tensile twins. The formation of twins resulted in an inhomogeneous microstructure, in which only the localized regions containing twins were refined and the regions deformed by slip remained coarse. The twinned grains, containing high stored energy and numerous high-angle grain boundaries, became the preferential sites of nucleation during subsequent recrystallization. During recrystallization heat treatment at 500~700°C, the cold-rolling texture (ϕ1=0°, Φ=35°, ϕ2=30°) diminished in intensity, whereas a recrystallization texture component (ϕ1=15°, Φ=35°, ϕ2=35°) appeared. The recrystallization heat treatment temperature affected the rate of recrystallization but not the texture characteristics per se. During the subsequent grain growth stage, the recrystallization texture component increased. This behavior was attributed to the growth of larger-than-average grains of this particular crystal orientation.The evolution of microstructure and texture during cold rolling and recrystallization annealing of commercial-purity Ti (CP-Ti) was established. Cold rolling to 40% reduction activated mechanical twinning- mostly > 3 2 11 < } 2 2 11 { compressive twins and > 1 1 10 < } 2 1 10 { tensile twins. The formation of twins resulted in an inhomogeneous microstructure, in which only the localized regions containing twins were refined and the regions deformed by slip remained coarse. The twinned grains, containing high stored energy and numerous high-angle grain boundaries, became the preferential sites of nucleation during subsequent recrystallization. During recrystallization heat treatment at 500~700°C, the cold-rolling texture (ϕ1=0°, Φ=35°, ϕ2=30°) diminished in intensity, whereas a recrystallization texture component (ϕ1=15°, Φ=35°, ϕ2=35°) appeared. The recrystallization heat treatment temperature affected the rate of recrystallization but not the texture characteristics per se. During the subsequent grain growth stage, the recrystallization texture component increased. This behavior was attributed to the growth of larger-than-average grains of this particular crystal orientation.

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