Study on Mechanical Properties at High Temperatures and Microstructure of Mg-12Gd-3Y-0.5Zr Magnesium Alloy

2014 ◽  
Vol 997 ◽  
pp. 618-623 ◽  
Author(s):  
Tian Dong Cao ◽  
Xiao Ming Yang

In this paper, tensile tests were carried out on the as-rolled and heat-treated Mg-12Gd-3Y-0.5Zr magnesium alloy at different temperatures. Tendency of tensile strength vs temperature was investigated and strengthening mechanism was discussed. It shows that both as-rolled and heat-treated Mg-12Gd-3Y-0.5Zr magnesium alloy have good mechanical properties at high temperatures. The reason why they have poor tension-compression asymmetry was discussed by their texture analysis. It is indicated that solution strengthening and precipitation strengthening were main strengthening mechanisam, and RE additons improve their thermal stability which lead to their high tensile strength at high temperatures.

2011 ◽  
Vol 686 ◽  
pp. 120-124
Author(s):  
Jin Ping Fan ◽  
She Bin Wang ◽  
Bing She Xu

The effects of Sr addition on the mechanical properties and microstructure of Mg-6Al mag- nesium alloy both at 25 °C and at 175 °C were investigated by means of OM, SEM and EDS and XRD. Upon the Sr addition of 2%, the tensile strength was increased by 7.2% to 184.4MPa at 25 °C, while it was increased by 30% to 155.4MPa at 175 °C. The strengthening mechanism of Mg-6Al-xSr at lower temperature (25 °C) was different from that at higher temperature (175°C). The results show that the addition of strontium effectively improved the microstructure and mechanical properties of magnesium alloy.


2019 ◽  
Vol 38 (2019) ◽  
pp. 892-896 ◽  
Author(s):  
Süleyman Tekeli ◽  
Ijlal Simsek ◽  
Dogan Simsek ◽  
Dursun Ozyurek

AbstractIn this study, the effect of solid solution temperature on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment was investigated. Following solid solution at five different temperatures for 2 hours, the AA7075 alloy was quenched and then artificially aged at 120∘C for 24 hours. Hardness measurements, microstructure examinations (SEM+EDS, XRD) and tensile tests were carried out for the alloys. The results showed that the increased solid solution temperature led to formation of precipitates in the microstructures and thus caused higher hardness and tensile strength.


2014 ◽  
Vol 606 ◽  
pp. 55-59 ◽  
Author(s):  
R. Senthil ◽  
A. Gnanavelbabu

Magnesium alloys are the very progressive materials whereon is due to improve their end-use properties. Especially, wrought Mg alloys attract attention since they have more advantageous mechanical properties than cast Mg alloys. Investigations were carried out the effects of heat treatment on tensile strength and microstructure of AZ61A magnesium alloy. The AZ61A Mg alloy is solution heat treated at the temperature of 6500F (343°C) for various soaking timing such as 120 min, 240 min and 360 minutes and allowed it cool slowly in the furnace itself. Magnesium alloys usually are heat treated either to improve mechanical properties or as means of conditioning for specific fabrication operations. Special attention had been focused on the analysis of mutual relations existing between the deformation conditions, microstructural parameters, grain size and the achieved mechanical properties. The result after the solution heat treatment, showed remarkably improved hardness, tensile strength and yield strength. It would be appropriate for a forming process namely isostatic forming process.


Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 884 ◽  
Author(s):  
Seyed Vahid Sajadifar ◽  
Emad Scharifi ◽  
Ursula Weidig ◽  
Kurt Steinhoff ◽  
Thomas Niendorf

This study focuses on the high temperature characteristics of thermo-mechanically processed AA7075 alloy. An integrated die forming process that combines solution heat treatment and hot forming at different temperatures was employed to process the AA7075 alloy. Low die temperature resulted in the fabrication of parts with higher strength, similar to that of T6 condition, while forming this alloy in the hot die led to the fabrication of more ductile parts. Isothermal uniaxial tensile tests in the temperature range of 200–400 °C and at strain rates ranging from 0.001–0.1 s−1 were performed on the as-received material, and on both the solution heat-treated and the thermo-mechanically processed parts to explore the impacts of deformation parameters on the mechanical behavior at elevated temperatures. Flow stress levels of AA7075 alloy in all processing states were shown to be strongly temperature- and strain-rate dependent. Results imply that thermo-mechanical parameters are very influential on the mechanical properties of the AA7075 alloy formed at elevated temperatures. Microstructural studies were conducted by utilizing optical microscopy and a scanning electron microscope to reveal the dominant softening mechanism and the level of grain growth at elevated temperatures.


2016 ◽  
Vol 51 (14) ◽  
pp. 1971-1977 ◽  
Author(s):  
NH Noor Mohamed ◽  
Hitoshi Takagi ◽  
Antonio N Nakagaito

The mechanical properties of cellulose nanofiber-reinforced polyvinyl alcohol composite were studied. Neat polyvinyl alcohol films, cellulose nanofiber sheets, and their nanocomposites containing cellulose nanofiber weight ratios of 5, 15, 30, 40, 45, 50 and 80 wt% were fabricated. Heat treatment by hot pressing at 180℃ was conducted on the specimens to study its effect to the mechanical properties and the results were compared with the non heat-treated specimens. Morphology of the composites was studied by scanning electron microscopy and the mechanical properties were evaluated by means of tensile tests. The results showed that increase of cellulose nanofiber content from 5 wt% to 80 wt% has increased the tensile strength of the composites up to 180 MPa, with cellulose nanofiber content higher than 40 wt% yielding higher tensile strength. The heat-treated specimens exhibited higher tensile strength compared to those of untreated specimens.


2013 ◽  
Vol 683 ◽  
pp. 82-89 ◽  
Author(s):  
Borpit Thossatheppitak ◽  
Surasak Suranuntchai ◽  
Vitoon Uthaisangsuk ◽  
Anchalee Manonukul ◽  
Pinai Mungsuntisuk

Nickel Aluminum Bronze (NAB) alloys have been widely used in different kinds of machine parts where the superior resistance to corrosion and erosion in saltwater is needed. In this work, mechanical properties at high temperatures and microstructures of a NAB alloy were investigated. First, NAB specimens were prepared as an as-cast ingot and were subsequently heat-treated at 675°C for 6 hours in order to improve microstructure and mechanical properties. The mechanical properties at high temperatures in form of the plastic flow curves of the NAB alloy were characterized by a deformation dilatometer. The NAB samples were compressed at high temperature and rapidly cooled down to room temperature. The deformation temperatures of 825°C, 850°C and 900°C, a strain rate of 0.01 s-1, and a maximum compression strain of 0.4 were considered. The influences of the temperature on flow behavior of the NAB alloy were investigated. The plastic stress-strain curves at different temperatures were compared with regard to the rate of material strain hardening and softening. It was found that the compression stresses decreased with increasing temperatures. Additionally, the resulted hardness and microstructures of the alloy after forming at high temperatures were analyzed.


2010 ◽  
Vol 148-149 ◽  
pp. 332-337 ◽  
Author(s):  
Yong Xue ◽  
Zhi Min Zhang ◽  
Li Hui Lang

In the present research, the influences of different extrusion ratios (15, 30, 45, 60, and 75), extrusion temperatures (300 , 340 , 380 , 420 , and 460 ), and subsequent heat treatment on the mechanical properties and microstructure of as-cast ZK60 magnesium alloy have been investigated through the tensile tests and via metallographic observation. The results show that forward extrusion process can refine the microstructure of as-cast ZK60 alloy effectively. If as-cast ZK60 alloys have been extruded with the extrusion ratio 45 at 380 ,420 and 460 , respectively, and then post-heat treatment was conducted, the ZK60 alloy’s strength is higher under T5 than T6 treatment. For as-cast ZK60 alloy processed by extrusion and T5 method, the most appropriate temperature for extrusion processing is 300 , at which its tensile strength are highest provided the extrusion ratio is 30 but yet its plasticity is best provided the extrusion ratio is 45. If forward extrusions were conducted at 380 , mechanical properties of ZK60 alloy have little difference as the extrusion ratio varies. When T6 treatment was conducted for the extruded bars, their mechanical properties were improved little, moreover, the bigger the extrusion ratio is, the higher the tensile strength and elongation of the extruded bars become.


2013 ◽  
Vol 749 ◽  
pp. 105-111
Author(s):  
Wei Yan ◽  
Yuan Hui Weng ◽  
Zong Qiang Luo ◽  
Wei Wen Zhang

The microstructures and mechanical properties of the Cu-17Ni-3Al-X alloy extruded at different temperatures were investigated by hardness and tensile tests, optical microscope and scanning electronic microscope. The experimental results showed that dynamic re-crystallization occured during the hot extrusion at 1000 . The grain size of the extruded alloy was significantly refined and the mechanical properties increased remarkably compared to the as-cast alloy. The alloy extruded at 1075 exhibited good mechanical properties with tensile strength of 994 MPa, Brinell hardness of 296 and elongation of 8.0%, which are 30%, 9% and 285% higher than that of the as-cast alloy.


2020 ◽  
Vol 897 ◽  
pp. 35-40
Author(s):  
Thanate Assawakawintip ◽  
Rochaya Chintavalakorn ◽  
Peerapong Santiwong ◽  
Anak Khantachawana

To investigate the effects of different temperatures for heat treatment of custom-made NiTi closed coil springs. NiTi closed coil springs (50.8% Ni-49.2%Ti) were manually fabricated around a 0.9mm diameter mandrel and heat treated at temperatures of 400°C, 450°C, and 500°C for 20 minutes. The outer diameter of each specimen was measured to determine the effect of heat treatment temperature on spring geometry. Tensile tests were carried out to measure the force levels at 3, 6, 9, and 12 mm of spring extension. Non-parametric statistical analyses were done to assess and compare the effects of different temperatures of heat treatment on the custom-made orthodontic closed coil springs. Heat treatment at lower temperatures produced larger outer coil diameters than at higher temperatures. Raising the temperature of heat treatment produced significant increases in force levels by 13-18 g especially between 400°C and 500°C at spring extensions of 3, 6 and 9 mm. The highest superelastic ratio of 5.44 was found in the NiTi coil springs that were heat treatment at 500°C for 20 minutes which signifies superelastic tendencies. The mechanical properties of NiTi closed coil springs are influenced by the temperature of heat treatment. The NiTi closed coil springs that were heat treated at 500°C for 20 minutes produce appropriate force levels to display a superelastic tendency for orthodontic use.


2013 ◽  
Vol 800 ◽  
pp. 225-228 ◽  
Author(s):  
Xiao Jie Song ◽  
Quan An Li ◽  
San Ling Fu

The effects of Y and Gd on the microstructure and mechanical properties of AZ81 magnesium alloy were studied by alloy preparation, microstructure analysis and mechanical property testing. The results show that moderate addition of Y and Gd to AZ61 magnesium alloy can obviously refine grains of AZ61 alloy, and decrease the amount of Mg17Al12 phase. With the increase of alloying elements, the tensile strength and elongation of aged AZ61 magnesium alloy at the temperature ranging of 25°C~175°C rise at first and then drop.When content of Y and Gd is up to 2.7%,the values of tensile strength of the alloy at room temperature and 175°C are up to their maximums, 254MPa and 164MPa respectively, while the elongation of the alloy are 22.9%,18.7% respectively. Y and Gd improve the mechanical properties of AZ61 alloy because of the grain refining strengthening, solution strengthening and the dispersion strengthening.


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