scholarly journals Effect of Injected Oxygen Amount on the Gas Porosity and Mechanical Properties of a Pore-Free Die-Cast Al–Si–Cu Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1805
Author(s):  
Ho-Jung Kang ◽  
Ho-Sung Jang ◽  
Seong-Hyo Oh ◽  
Pil-Hwan Yoon ◽  
Gyu-Heun Lee ◽  
...  

With the rise in the demand for eco-friendly and electric vehicles, welding and heat treatment are becoming very important to meet the necessary weight reduction, complexity, and high functionality of die castings. Pore-free (PF) die casting is an effective process that enables heat treatment and welding due to low gas porosities. Indeed, this process affords castings of low gas porosity, similar to those attained by high-vacuum die casting. In this study, we compared the gas porosities of different castings fabricated by PF die casting using varied injected oxygen amounts. The castings were all subjected to T6 heat treatment and analyzed by computed tomography (CT) to compare their microstructure and mechanical properties before and after T6 heat treatment. The results revealed that with the increasing injected oxygen amount, the gas porosity of the specimens decreased while their mechanical properties increased. In particular, the gas porosity was the lowest at 1.26 L. Moreover, the 1.26 L specimen displayed the best tensile strength, yield strength, and elongation results. Finally, Weibull distribution analysis revealed that the tensile strength and elongation repeatability and reproducibility increased with increasing injected oxygen amount.

2019 ◽  
Vol 944 ◽  
pp. 64-72
Author(s):  
Qing Feng Yang ◽  
Cun Juan Xia ◽  
Ya Qi Deng

Bulky sample was made by using TIG wire and arc additive manufacturing (WAAM) technology, in which Ф1.6 mm filler wire of in-situ TiB2/Al-Si composites was selected as deposition metal, following by T6 heat treatment. The microstructure and mechanical properties of the bulky sample before and after heat treatment were analyzed. Experimental results showed that the texture of the original samples parallel to the weld direction and perpendicular to the weld direction was similar consisting of columnar dendrites and equiaxed crystals. After T6 heat treatment, the hardness of the sample was increased to 115.85 HV from 62.83 HV, the yield strength of the sample was 273.33 MPa, the average tensile strength was 347.33 MPa, and the average elongation after fracture was 7.96%. Although pore defects existed in the fracture, yet the fracture of the sample was ductile fracture.


2010 ◽  
Vol 148-149 ◽  
pp. 346-352
Author(s):  
Dong Nan Li ◽  
Wen Zhe Chen ◽  
Jun Tian

The semi-solid slurry of AZ91D magnesium alloy was prepared by twin-screw stirring mixer, the microstructure and mechanical properties of semi-solid formed magnesium alloy AZ91D produced by rheo-diecasting and conventional liquid die casting were investigated, respectively. The strengthen mechanism of the semi-solid formed magnesium alloy after heat treatment was analysed by EDS. The results show that the mechanical properties of semi-solid formed magnesium alloy can be enhanced markedly by T4 and T6 heat treatment, owing to decrease of the porosity and less segregation in casting, brittle eutectic compounds dissolves gradually into α-Mg matrix, and the primary phase α-Mg decomposes in the course of heat treatment. In as-cast state, the tensile strength, elongation and hardness of semi-solid formed magnesium alloy AZ91D are 222MPa, 2.3% and 74 HBS, respectively. In T4 heat treatment state, the tensile strength and elongation are increased by 13% and 210%, and in T6 heat treatment state, the tensile strength and hardness are increased by 11% and 16%. The mechanical properties of castings formed by conventional liquid die casting are deteriorated distinctly after T6 heat treatment due to its porosity and crack defects.


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.


Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2065
Author(s):  
Fei Liu ◽  
Haidong Zhao ◽  
Runsheng Yang ◽  
Fengzhen Sun

Al–Si–Mg based alloys can provide high strength and ductility to satisfy the increasing demands of thin wall castings for automotive applications. This study has investigated the effects of T6 heat-treatment on the microstructures, the local mechanical properties of alloy phases and the fracture behavior of high vacuum die-cast AlSiMgMn alloys using in-situ scanning electron microscopy (SEM) in combination with nano-indentation testing. The microstructures of the alloys at as-cast and T6 treated conditions were compared and analyzed. It is found that the T6 heat treatment plays different roles in affecting the hardness and the Young’s modulus of alloy phases. This study also found that the T6 heat treatment would influence the failure modes of the alloys. The mechanisms of crack propagation in the as-cast and T6 treated alloys were also analyzed and discussed.


2013 ◽  
Vol 690-693 ◽  
pp. 44-48
Author(s):  
Feng Wang ◽  
Zhi Wang ◽  
Zheng Liu ◽  
Ping Li Mao

In this paper, developed a non-aluminum die casting magnesium alloys were studied based on Mg-xGd-Y-Zr(x=6, 8, 12 wt.%)alloys in cold chamber press. The microstructures and mechanical properties of die casting GWK alloys have been investigated using OM, SEM, XRD, EDS and mechanical property test. The experimental results show that with increasing Gd content of Mg-xGd-Y-Zr alloys, the tensile strength increase, but elongation decrease. In particular, die casting GWK alloys after short-term and low-temperature solid solution treatment (T4) have a small variation in grain size and more uniform microstructures, and the second phases distribute at the grain boundaries in form of discontinuous rod shape or granule shape, which result in an obvious improvement in tensile mechanical properties of alloys. The Mg-12Gd-3Y-0.5Zr die casting alloy exhibit maximum tensile strength after solution heat treatment, and the value is 269MPa at room temperature. The effect of solution heat treatment on die casting Mg-xGd-Y-Zr alloys was also discussed.


Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2131
Author(s):  
Bo-Chin Huang ◽  
Fei-Yi Hung

This study investigated the microstructure, mechanical properties, impact toughness, and erosion characteristics of Al-10Si-Mg alloy specimens manufactured using the selective laser melting (SLM) method with or without subsequent T6 heat treatment. Furthermore, the erosion phase transformation behavior of the test specimens was analyzed, and the effect of the degradation mechanism on the tensile mechanical properties and impact toughness of the SLM Al-10Si-Mg alloy specimens before and after particle erosion was compared. The experimental results indicated that the Al-10Si-Mg alloy subjected to T6 heat treatment has better erosion resistance than the as-fabricated material. The tensile strength and fracture toughness of both specimen groups decreased due to the formation of microcracks on the surface caused by particle erosion. Nevertheless, the erosion-induced silicon nanoparticle solid solution softens the Al matrix and improves the elongation of the SLM Al-10Si-Mg alloy.


2016 ◽  
Vol 850 ◽  
pp. 762-767
Author(s):  
Shun Cheng Wang ◽  
Dong Fu Song ◽  
Jing Xu ◽  
Kai Hong Zheng

In the present investigation the casting-forging integrated technology was adopted to manufacture Al-1.1Mg-0.6Si-0.4Cu alloy automobile brake calipers. The effect of forging pressure on the microstructure and mechanical properties of Al-1.1Mg-0.6Si-0.4Cu alloy calipers were studied. The results showed that the shrinkage porosities and cracks in the Al-1.1Mg-0.6Si-0.4Cu alloy calipers could be removed by the forging process. The ultimate tensile strength and elongation of Al-1.1Mg-0.6Si-0.4Cu alloy calipers increased with the increase of forging pressure. When the forging pressure was 120 MPa, the ultimate tensile strength and elongation of Al-1.1Mg-0.6Si-0.4Cu alloy calipers with T6 heat treatment were 365.3 MPa and 11.5%, which were improved by 22.8% and 38.2%, respectively compared with that of Al-1.1Mg-0.6Si-0.4Cu alloy calipers without forging. The tensile fracture images revealed that the fracture modes of Al-1.1Mg-0.6Si-0.4Cu alloy calipers were more ductile at higher forging pressure.


2015 ◽  
Vol 60 (2) ◽  
pp. 627-632 ◽  
Author(s):  
J. Pezda

AbstractThe paper presents test results concerning an effect of the heat treatment on microstructure and mechanical properties of eutectic EN AC-AlSi12CuNiMg (EN AC-48000) alloy according to the EN 1706:2010 (tensile strength –Rm, hardness –HB10/1000/30) modified with strontium. Solution heat treatment and ageing treatment temperature ranges were selected on base of heating (melting) curves recorded with use of the ATD method. Temperatures of the solution heat treatment were 500, 520, and 535°C ±5°C, while the solution time ranged from 0.5 to 3 h (0.5; 1.5 and 3 h). Temperature of the solution heat treatment amounted to 180, 235 and 310°C, while the ageing time ranged from 2 to 8 h (2, 5 and 8 h).Obtained results have enabled determination of optimal parameters of the T6 heat treatment in aspect of improvement of tensile strengthRmand hardnessHBof the alloy, with reduced time of individual treatments and determination of mathematical relationships enabling prediction of these mechanical properties.


2011 ◽  
Vol 71-78 ◽  
pp. 3329-3332
Author(s):  
Ke Jie Li

The Mg-12Gd-2Y-0.5Sm-0.5Sb-0.5Zr (wt.%) alloy was prepared by casting technology. The microstructure of alloy was then investigated after T6 heat treatment. The results show that at 523K, the alloy has shown the superior tensile strength (i.e. 345.5 MPa). When experimental alloy was stretched with temperature increasing from 293K to 523K, the increases of deformation strengthening and critical crack propagation stress caused the anomalous temperature dependence of tensile strength.


2014 ◽  
Vol 794-796 ◽  
pp. 501-507 ◽  
Author(s):  
Haris Rudianto ◽  
Jang Kwang Joo ◽  
Yang Sang Sun ◽  
Kim Yong Jin ◽  
Ivo Dlouhy

In this research, Al-5.5Zn-2.5Mg-0.5Cu was investigated. Compaction pressure at 700 MPa was carried out to make green body materials. Strong interlocking between particles is expected after high compaction process. Sintering of aluminum composites powder is sensitive to the humidity. High purity nitrogen gas was used to sinter this material from 560o-585°C for 1 hour. Sintering density increased with increasing sintering temperature and reached 96% relative sintering density at 580°C. Mechanical properties investigation of this material was done with hardness and tensile test. At optimum sintering conditions, this material has 40 HRB hardness and 329 MPa tensile strength. Based on chemical composition, this material has possibility to improve mechanical properties by T6 heat treatment. Strengthening precipitates such as MgZn2 and CuAl2 were expected as results from T6 heat treatment. Mechanical properties improved with this treatment with reaching 513 MPa of tensile strength. SEM, DSC-TGA and X-Ray Diffraction were used to characterize this material.


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