Cellular Microstructure and Mechanical Properties of a Directionally Solidified Al-1.0wt%Fe Alloy

2010 ◽  
Vol 636-637 ◽  
pp. 564-570 ◽  
Author(s):  
Pedro R. Goulart ◽  
J.E. Spinelli ◽  
F. Bertelli ◽  
Wislei R.R. Osório ◽  
Noé Cheung ◽  
...  

Upward directional transient solidification experiments have been carried out with an Al-1.0wt%Fe alloy. Tensile tests were carried out with samples collected along the casting length and these results have been correlated with measured cell spacings, since cellular growth has prevailed along the directionally solidified casting. The resulting mechanical properties include ultimate tensile strength, yield tensile strength and elongation. The used casting assembly was designed in such a way that the heat was extracted only through the water-cooled system at bottom of the casting. During non-equilibrium solidification, typical of DC (direct chill) castings, different cooling rates occur from the casting cooled surface up to the top of the casting, causing the formation of metastable intermetallic phases (AlmFe, Al6Fe, etc) in addition to the stable Al3Fe phase. The extensive presence of plate-like Al3Fe phase in the as-cast structure adversely influences the mechanical properties of Al-Fe alloys, since this morphology is more likely to induce microcracks than the fibrous Al6Fe phase. In order to permit an appropriate characterization of these intermetallic phases, they were extracted from the aluminum-rich matrix by using a dissolution technique. These phases were then investigated by optical microscopy and SEM techniques. It was found that the ultimate tensile strength, the yield strength and the elongation increase with decreasing cell spacing and experimental laws correlating cell spacing and these mechanical properties have been established.

2022 ◽  
Vol 327 ◽  
pp. 82-97
Author(s):  
He Qin ◽  
Guang Yu Yang ◽  
Shi Feng Luo ◽  
Tong Bai ◽  
Wan Qi Jie

Microstructures and mechanical properties of directionally solidified Mg-xGd (5.21, 7.96 and 9.58 wt.%) alloys were investigated at a wide range of growth rates (V = 10-200 μm/s) under the constant temperature gradient (G = 30 K/mm). The results showed that when the growth rate was 10 μm/s, different interface morphologies were observed in three tested alloys: cellular morphology for Mg-5.21Gd alloy, a mixed morphology of cellular structure and dendritic structure for Mg-7.96Gd alloy and dendrite morphology for Mg-9.58Gd alloy, respectively. Upon further increasing the growth rate, only dendrite morphology was exhibited in all experimental alloys. The microstructural parameters (λ1, λ2) decreased with increasing the growth rate for all the experimental alloy, and the measured λ1 and λ2 values were in good agreement with Trivedi model and Kattamis-Flemings model, respectively. Vickers hardness and the ultimate tensile strength increased with the increase of the growth rate and Gd content, while the elongation decreased gradually. Furthermore, the relationships between the hardness, ultimate tensile strength, the growth rate and the microstructural parameters were discussed and compared with the previous experimental results.


2021 ◽  
Vol 2 (12 (110)) ◽  
pp. 22-31
Author(s):  
Agus Widyianto ◽  
Ario Sunar Baskoro ◽  
Gandjar Kiswanto ◽  
Muhamad Fathin Ginanjar Ganeswara

Orbital pipe welding was often used to manufacture piping systems. In orbital pipe welding, a major challenge is the welding torch’s position during the welding process, so that additional methods are needed to overcome these challenges. This paper discusses the influence of welding sequence and welding current on distortion, mechanical properties and metallurgical observations in orbital pipe welding with SS 316L pipe square butt joints. The variation of the orbital pipe welding parameters used is welding current and welding sequence. The welding current used is 100 A, 110 A, and 120 A, while the welding sequence used is one sequence, two sequences, three sequences, and four sequences. The welding results will be analyzed from distortion measurement, mechanical properties test and metallurgical observations. Distortion measurements are made on the pipe before welding and after welding. Testing of mechanical properties includes tensile tests and microhardness tests, while metallurgical observations include macrostructure and microstructural observations. The results show that maximum axial distortion, transverse distortion, ovality, and taper occurred at a welding current of 120 A with four sequences of 445 µm, 300 µm, 195 µm, and 275 µm, respectively. The decrease in ultimate tensile strength is 51 % compared to the base metal’s ultimate tensile strength. Horizontal and vertical microhardness tests show that welding with one sequence produces the greatest microhardness value, but there is a decrease in the microhardness value using welding with two to four sequences. Orbital pipe welding results in different depths of penetration at each pipe position. The largest and smallest depth of penetration was 4.11 mm and 1.60 mm, respectively


2013 ◽  
Vol 380-384 ◽  
pp. 4372-4375
Author(s):  
Li Zhang ◽  
Zheng Liu ◽  
Ping Li Mao

The microstructure evolution and mechanical properties of as-extruded Mg-2.5 Zn-0.5Y Mg alloy were investigated. The grainy intermetallic phases (I-phase and w-phase) observed in the as-cast Mg-2.5Zn-0.5Y alloy distributed homogeneously in the hot extruded alloys. Compared with the cast one, the extruded alloy shows predominant mechanical properties as the result of refined microstructure and the dispersed intermetallic phases formed during hot extrusion. The ultimate tensile strength and the yield tensile strength of the extruded alloy were 354.8 MPa and 305.9MPa respectively.


2017 ◽  
Vol 17 (4) ◽  
pp. 179-184
Author(s):  
Xuesong Fu ◽  
Yan Yang ◽  
QuanYang Ma ◽  
Xiaodong Peng ◽  
Tiancai Xu

AbstractMg-0.5Si-xSn (x=0.95, 2.9, 5.02wt.%) alloys were cast and extruded at 593K (320oC) with an extrusion ratio of 25. The microstructure and mechanical properties of as-cast and extruded test alloys were investigated by OM, SEM, XRD and tensile tests. The experimental results indicate that the microstructure of the Mg-0.5Si-xSn alloys consists of primary α-Mg dendrites and an interdendritic eutectic containing α-Mg, Mg2Si and Mg2Sn. There is no coarse primary Mg2Si phase in the test alloys due to low Si content. With the increase in the Sn content, the Mg2Si phase was refined. The shape of Mg2Si phase was changed from branch to short bar, and the size of them were reduced. The ultimate tensile strength and yield strength of Mg-0.52Si-2.9Sn alloy at the temperature of 473K (200oC) reach 133MPa and 112MPa respectively. Refined eutectic Mg2Si phase and dispersed Mg2Sn phase with good elevated temperature stability are beneficial to improve the elevated temperature performance of the alloys. However, with the excess addition of Sn, large block-like Mg2Sn appears around the grain boundary leading to lower mechanical properties.


2017 ◽  
Vol 898 ◽  
pp. 259-264 ◽  
Author(s):  
Shao Chen Zhang ◽  
Jin Feng Leng ◽  
Chen Xue Li ◽  
Xin Ying Teng

A356.2 aluminum alloy (Al–7Si–0.35Mg) has been widely used in automotive and aircraft industries. Previous studies found that the metamorphism effect of rare earth is better than other type of elements because of long modification time and good stability. The influence of Yb addition (0%, 0.2%, 0.4% and 0.6%) and T6 heat treatment on A356.2 alloy has been investigated in this work. The microstructures and mechanical properties of the specimen after T6 treatment were examined by optical microscope, scanning electronic microscope and tensile tests. Experimental results showed that Yb could reduce the size of α-Al and change the Si morphology from needle-like to fine spheroidal particles. With the increase of Yb content, the ultimate tensile strength increased gradually. When adding 0.4%Yb, the alloy achieved the highest ultimate tensile strength (252 MPa) and hardness (97.3HB), 10.12% and 37.66% higher than the alloy with no Yb addition. Tensile fracture analysis showed that the fracture mechanism for A356.2 aluminum alloy after T6 treatment is transgranular/intergranular mixed mode of fracture.


2012 ◽  
Vol 482-484 ◽  
pp. 1530-1533
Author(s):  
Ming Li Huang ◽  
Hua Ying Li ◽  
Hua Ding

In the present work, mechanical properties and microstructures of hot-rolled and solution-treated Fe-26Mn-6Al-1C steel (6Al steel) were investigated. Tensile tests were carried out at room temperature. The samples were characterized by using XRD, OM, SEM and TEM. The results suggested that the microstructure of the hot rolled 6Al steel was fully austenitic. After solution treatment and deformation, the microstructure was still single austenite. With the increase of the solution treatment temperatures, the strength decreased and the elongation increased. After solution treated at 1100°C for 1h, the yield strength, ultimate tensile strength and elongation were 378MPa, 756MPa and 57%.


2020 ◽  
Vol 26 (3) ◽  
pp. 127-130
Author(s):  
Nassim Markiz ◽  
Eszter Horváth ◽  
Péter Ficzere

AbstractIn the recent years, additive manufacturing became an interesting topic in many fields due to the ease of manufacturing complex objects. However, it is impossible to determine the mechanical properties of any additive manufacturing parts without testing them. In this work, the mechanical properties with focus on ultimate tensile strength and modulus of elasticity of 3D printed acrylonitrile butadi-ene styrene (ABS) specimens were investigated. The tensile tests were carried using Zwick Z005 loading machine with a capacity of 5KN according to the American Society for Testing and Materials (ASTM) D638 standard test methods for tensile properties of plastics. The aim of this study is to investigate the influence of printing direction on the mechanical properties of the printed specimens. Thus, for each printing direction ( and ), five specimens were printed. Tensile testing of the 3D printed ABS specimens showed that the printing direction made the strongest specimen at an ultimate tensile strength of 22 MPa while at printing direction it showed 12 MPa. No influence on the modulus of elasticity was noticed. The experimental results are presented in the manuscript.


2013 ◽  
Vol 22 (5) ◽  
pp. 096369351302200
Author(s):  
Mostefa Bourchak ◽  
Adnan Khan ◽  
Khalid A. Juhany

The purpose of this study is to compare the mechanical properties in the form of ultimate tensile strength, ultimate tensile strain and Young's modulus of an epoxy resin at different curing cycles. The work carried out consisted of investigating the effect of preheating time and then the effect of post-curing time at the same temperature. Five repeats of static tensile tests were then carried out using universal test machine. Results indicated that compared to a shorter epoxy resin preheat duration of 15 min at 80°C, a longer duration of 30 min at 80°C of preheating degrades the material ultimate tensile strength and ultimate tensile strain leading to a suffer material. However, compared to no further post-curing of the epoxy resin, a two-hour post-cure duration at 80°C slightly increased the ultimate tensile strength and significantly decreased the ultimate tensile strain making the material even suffer than in the case of preheating. The implication is that in-house cure cycle tests should be carried out to characterize the resin instead of exclusively relying on resin manufacturer proposed cure cycles.


Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 384
Author(s):  
Andong Du ◽  
Anders E. W. Jarfors ◽  
Jinchuan Zheng ◽  
Kaikun Wang ◽  
Gegang Yu

The effect of lanthanum (La)+cerium (Ce) addition on the high-temperature strength of an aluminum (Al)–silicon (Si)–copper (Cu)–magnesium (Mg)–iron (Fe)–manganese (Mn) alloy was investigated. A great number of plate-like intermetallics, Al11(Ce, La)3- and blocky α-Al15(Fe, Mn)3Si2-precipitates, were observed. The results showed that the high-temperature mechanical properties depended strongly on the amount and morphology of the intermetallic phases formed. The precipitated tiny Al11(Ce, La)3 and α-Al15(Fe, Mn)3Si2 both contributed to the high-temperature mechanical properties, especially at 300 °C and 400 °C. The formation of coarse plate-like Al11(Ce, La)3, at the highest (Ce-La) additions, reduced the mechanical properties at (≤300) ℃ and improved the properties at 400 ℃. Analysis of the strengthening mechanisms revealed that the load-bearing mechanism was the main contributing mechanism with no contribution from thermal-expansion mismatch effects. Strain hardening had a minor contribution to the tensile strength at high-temperature.


Author(s):  
Aleksandra Towarek ◽  
Wojciech Jurczak ◽  
Joanna Zdunek ◽  
Mariusz Kulczyk ◽  
Jarosław Mizera

AbstractTwo model aluminium-magnesium alloys, containing 3 and 7.5 wt.% of Mg, were subjected to plastic deformation by means of hydrostatic extrusion (HE). Two degrees of deformation were imposed by two subsequent reductions of the diameter. Microstructural analysis and tensile tests of the materials in the initial state and after deformation were performed. For both materials, HE extrusion resulted in the deformation of the microstructure—formation of the un-equilibrium grain boundaries and partition of the grains. What is more, HE resulted in a significant increase of tensile strength and decrease of the elongation, mostly after the first degree of deformation.


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