scholarly journals Microstructure and Mechanical Properties of High Vacuum Die-Cast AlSiMgMn Alloys at as-Cast and T6-Treated Conditions

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2065
Author(s):  
Fei Liu ◽  
Haidong Zhao ◽  
Runsheng Yang ◽  
Fengzhen Sun
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Failure Modes ◽  
High Vacuum ◽  
High Strength ◽  
Thin Wall ◽  
T6 Heat Treatment ◽  
Die Cast ◽  
Strength And Ductility

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.

Effect of Alloying and Thermal Processing on Mechanical Properties of TiAl Alloys

2016 ◽  
Vol 258 ◽  
pp. 501-505
Author(s):  
Alice Chlupová ◽  
Milan Heczko ◽  
Karel Obrtlík ◽  
Přemysl Beran ◽  
Tomáš Kruml
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Processing ◽  
Lamellar Microstructure ◽  
High Strength ◽  
Fatigue Behaviour ◽  
Tial Alloys ◽  
Working Temperature ◽  
Β Phase ◽  
Strength And Ductility

Two γ-based TiAl alloys with 7 at.% of Nb, alloyed with 2 at.% Mo and 0.5 at.% C, were studied. A heat treatment leading to very fine lamellar microstructure was applied on both alloys. Microstructure after the heat treatment was described and mechanical properties including fatigue behaviour were measured. The as-received material alloyed with C possesses high strength and very limited ductility, especially at RT. After application of selected heat treatment it becomes even more brittle; therefore, this process could be considered as not appropriate for this alloy. On the contrary, in the case of Mo alloyed material, both strength and ductility are improved by the heat treatment at RT and usual working temperature (~750 °C). Presence of the β phase is responsible for this effect. The selected heat treatment thus can be an alternative for this alloy to other thermomechanical treatments as high temperature forging.

Microstructure and Mechanical Properties of TiB2/ Al-Si Composites Fabricated by TIG Wire and Arc Additive Manufacturing

2019 ◽  
Vol 944 ◽  
pp. 64-72
Author(s):  
Qing Feng Yang ◽  
Cun Juan Xia ◽  
Ya Qi Deng
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
Yield Strength ◽  
Filler Wire ◽  
T6 Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
Before And After

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.

scholarly journals The Effect of Heat Treatment on Mechanical Properties of Pulsed Nd:YAG Welded Thin Ti6Al4V

2011 ◽  
Vol 189-193 ◽  
pp. 3672-3677 ◽  
Author(s):  
Yu Fan ◽  
Philip H. Shipway ◽  
Geoff D. Tansley ◽  
Jie Xu
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Beam Quality ◽  
Thin Sheet ◽  
Welding Process ◽  
High Strength ◽  
Travel Speed ◽  
Laser Beam Quality ◽  
Strength And Ductility ◽  
Martensite Structure

Pulsed Nd:YAG has been adopted successfully in welding process of thin (0.7 mm) Ti6Al4V. Laser welding of such thin sheet requires a small focal spot, good laser beam quality and fast travel speed, since too much heat generation can cause distortion for thin sheet weld. The microstructures of Ti6Al4V were complex and strongly affected the mechanical properties. These structures include: α´ martensite, metastable β, Widmanstätten, bimodal, lamellar and equiaxed microstructure. Bimodal and Widmanstätten structures exhibit a good-balance between strength and ductility. The microstructure of pulsed Nd:YAG welded Ti6Al4V was primarily α´ martensite, which showed the lowest ductility but not significantly high strength. A heat treatment at 950 followed by furnace cooling can transform the microstructure in the weld from α´ martensite structure into Widmanstätten structure.

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 ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Die Casting ◽  
High Vacuum ◽  
Distribution Analysis ◽  
T6 Heat Treatment ◽  
Gas Porosity ◽  
Before And After ◽  
Die Castings

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.

scholarly journals Structure and Properties of High-Strength Ti Grade 4 Prepared by Severe Plastic Deformation and Subsequent Heat Treatment

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1116
Author(s):  
Alena Michalcová ◽  
Dalibor Vojtěch ◽  
Jaroslav Vavřík ◽  
Kristína Bartha ◽  
Přemysl Beran ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Strength ◽  
Ultimate Tensile Stress ◽  
Internal Stresses ◽  
In Situ Xrd ◽  
Microstructure Observation

Severe plastic deformation represented by three passes in Conform SPD and subsequent rotary swaging was applied on Ti grade 4. This process caused extreme strengthening of material, accompanied by reduction of ductility. Mechanical properties of such material were then tuned by a suitable heat treatment. Measurements of in situ electrical resistance, in situ XRD and hardness indicated the appropriate temperature to be 450 °C for the heat treatment required to obtain desired mechanical properties. The optimal duration of annealing was stated to be 3 h. As was verified by neutron diffraction, SEM and TEM microstructure observation, the material underwent recrystallization during this heat treatment. That was documented by changes of the grain shape and evaluation of crystallite size, as well as of the reduction of internal stresses. In annealed state, the yield stress and ultimate tensile stress decreased form 1205 to 871 MPa and 1224 to 950 MPa, respectively, while the ductility increased from 7.8% to 25.1%. This study also shows that mechanical properties of Ti grade 4 processed by continual industrially applicable process (Conform SPD) are comparable with those obtained by ECAP.

Mechanism for Mechanical Properties of the A357 Connection Beam Casting from Solidification

2012 ◽  
Vol 217-219 ◽  
pp. 1762-1768
Author(s):  
Zhen Zhong Fan ◽  
Jiong Li Li ◽  
Sha Sha Li
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cooling Rate ◽  
Performance Test ◽  
Casting Defects ◽  
Thin Wall ◽  
T6 Heat Treatment ◽  
Microstructure Observation ◽  
Mechanics Performance ◽  
A357 Aluminum Alloy

The overall distribution of mechanical properties of A357 aluminum alloy connection beam casting after solidification and T6 heat treatment was researched in this paper, through the mechanics performance test, metallographic microstructure observation, SEM and EDS scanning analysis of the fracture surface, the ensemble mechanical properties of connection beam casting was characterized. The results show that owing to the low cooling rate nearby the arc thick-walled department and the trasition region between the thick and thin-walled of the connection beam casting, leading to the morphology of the crystalline grains and silicon particles in this vicinity are thick. Some casting defects such as oxide inclusions located in the lateral stud district were caused by the strong erosion of high temperature melting liquid during the pouring process, resulting in the mechanical properties decreased significantly, casting defects were not eliminated in the T6 heat treatment process. Due to both the high cooling rate and the smooth pouring process among the thin-wall, forward stud and square box region of A357 aluminum connection beam casting, after the solid solution and limitation strengthening of T6 heat treatment, resulting in the overall mechanical properties were higher than other areas. The tensile strength has reached 360.96MPa, also with the yield strength and elongation respectively attained 297.95MPa and 8.82 %.

Solidification Behavior and Mechanical Properties of Al-Si-Mg Alloy with Ti Addition

2016 ◽  
Vol 850 ◽  
pp. 594-602 ◽  
Author(s):  
Cong Xu ◽  
Cheng Yuan Wang ◽  
Hai Jun Yang ◽  
Zhi Guo Liu ◽  
Hiroshi Yamagata ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cast Alloy ◽  
Solidification Behavior ◽  
A357 Alloy ◽  
T6 Heat Treatment ◽  
Interdendritic Space ◽  
Cast Alloys ◽  
Ti Addition ◽  
Strength And Ductility

The solidification behavior, microstructural evolution and mechanical properties of Al-Si-Mg foundry alloy with different Ti additions were investigated in the present study. The solidification behavior of those A357 alloys was analyzed through thermal analysis. The microstructures were examined by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the addition of Ti could refine grains of A357 as-cast alloy due to a good restriction on the grain growth, but Ti could not refine secondary dendrite arm spacing (SDAS), thus mechanical properties of the A357 as-cast alloy did not improved significantly. After T6 heat treatment, the microstructure with α-Al dendrites with the Al-Si eutectics at interdendritic space was replaced by a homogeneous α-Al matrix with a nonuniform dispersion of discrete, spheroidizing and coarse silicon particles. Hence, compared with the as-cast alloys, both of the strength and ductility of the T6 treated alloys are significantly improved, and an optimal combination of strength and elongation of the A357 alloy can be achieved by the 0.8 wt.% Ti addition after T6 heat treatment.

UNS A97075

Alloy Digest ◽  
1986 ◽  
Vol 35 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
High Strength ◽  
Heat Treating ◽  
Good Resistance ◽  
Temperature Performance ◽  
Structural Applications ◽  
Structural Parts ◽  
Very High

Abstract UNS No. A97075 is a wrought precipitation-hardenable aluminum alloy. It has excellent mechanical properties, workability and response to heat treatment and refrigeration. Its typical uses comprise aircraft structural parts and other highly stressed structural applications where very high strength and good resistance to corrosion are required. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fatigue. It also includes information on low temperature performance as well as forming, heat treating, and machining. Filing Code: Al-269. Producer or source: Various aluminum companies.

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