scholarly journals Microstructure and Mechanical Behavior of Mg-0.5Si-xSn Alloys

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.

2010 ◽  
Vol 139-141 ◽  
pp. 180-184
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) and extrusion temperatures (300°C, 330°C, 360°C, 390°C, 420°C) on the mechanical properties and microstructure of homogenized AZ80 alloy have been investigated through the tensile tests and via metallographic microscope observation. The results show that the alloy’s grain is small and small amounts of black hard and brittle second-phase β (Mg17Al12) are precipitated uniformly along the grain boundary causing the gradual increase of the alloy’s tensile strength at 330°C. When the extrusion temperature is up to 390°C, the grain size increases significantly, but the second phase precipitation along grain boundaries transforms into continuous and uniform-distribution precipitation within the grain. In this case, when the extrusion ratio is 60, the alloy’s tensile strength reaches its peak 390Mpa. As the extrusion temperature increases, inhomogeneous precipitation of the second-phase along grain boundaries increases, causing the decrease of the alloy’s strength. At the same temperature, the tensile strength increases firstly and then decreases as extrusion ratio increases. With the gradual increase of the refinement grain, the dispersed precipitates increase and the alloy’s tensile strength and plasticity reach their peaks when the extrusion temperature is 390°C. As the grain grows, the second phase becomes inhomogeneous distribution, and the alloy’s strength and plasticity gradually decrease.


2007 ◽  
Vol 546-549 ◽  
pp. 237-240 ◽  
Author(s):  
Bin Chen ◽  
Dong Liang Lin ◽  
Xiao Qin Zeng ◽  
Chen Lu

The elevated temperature mechanical behavior of Mg-Y-Zn alloys was investigated. It was found that the extruded Mg-Y-Zn alloy exhibited excellent mechanical properties both at ambient temperature and elevated temperature. With the increase of tensile temperature, the ultimate tensile strengths of Mg-Y-Zn alloys decreased and their elongations increased. The ultimate tensile strengths increased and elongations decreased with the increase of yttrium content. However, a gradual increase in the ultimate tensile strength and elongation both at ambient temperature and elevated temperature was obtained by increasing both yttrium and zinc contents. The fracture modes of Mg-Y-Zn alloys at different tensile temperature were also investigated.


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


Author(s):  
Ruyao Wang ◽  
Wei Hua Lu

The microstructure, mechanical properties, and fracture of nodular silicon hypereutectic Al–Si alloys containing 12–30 wt% Si are discussed. The eutectic and primary silicon particles are nodulized, offering an average aspect ratio of 1.60–1.70 with a designed modification practice followed by a solution heat treatment of 8–10 h at 510°C–520°C. Such a soaking temperature does not result in coarsening or clustering of the silicon particles. Nodulization of silicon phase leads to an increase in the tensile strength and ductility of alloys at room and elevated temperatures compared with commercial Al–Si alloys. Increasing the Si content leads the tensile strength and elongation of alloys at room temperature to fall down due to the formation of coarsen primary Si grains, but the ultimate tensile strength at 300°C remains unchanged. The ultimate tensile strength σb-alloy of hypereutectic Al–Si alloys is inversely proportional to square root of maximum silicon size dmax. The initiation and propagation of the crack with continuous increase in applied loading were observed under scanning electron microscope. The fracture surfaces in nodular silicon Al–Si alloys are composed of equiaxed ductile dimples. The finite-element method has been used to study the stress distribution within the different morphologies of Si grain and how Si and Al phases interact during loading.


2013 ◽  
Vol 668 ◽  
pp. 823-829 ◽  
Author(s):  
Xiu Qing Zhang ◽  
Ge Chen ◽  
Yang Wang ◽  
Min Yu Han

Homogenized magnesium alloy Mg-6Zn-Si-0.25Ca has been hot-extruded and then aging treated for improving the magnesium alloy plastic deformation ability and promoting applications of magnesium alloys. In the hot extrusion process, the influences of extrusion parameters for microstructures and mechanical properties of Mg-6Zn-Si-0.25Ca magnesium alloy were investigated. The results show that dynamic recrystallization occurred during hot extrusion. Compared with as-cast alloy, the grains are fined remarkably, and the mechanical properties are enhanced obviously. Twin crystals appeared in grains after hot extrusion, with the extrusion temperature rising, twin crystal structures has been reduced. Aging further increased the mechanical properties of the estruded alloy. The ultimate tensile strength of Mg-6Zn-Si-0.25Ca alloy is about 385 MPa and the elongation is about 11% when extruded at 320°C(extrusion ratio is 10) and aged at 190°C for 8h.


2008 ◽  
Vol 141-143 ◽  
pp. 779-784 ◽  
Author(s):  
Hai Ping Cao ◽  
Olof Granath ◽  
Magnus Wessen

The RHEOMETALTM process is a commercially used semi-solid process for production of high integrity cast components. The process differs from most other semi-solid casting processes in that temperature control is not necessary during processing and large amount of slurry with required solid fraction can be quickly produced. The simplicity of this process has led to a large commercial interest during the last year. This work is based on an investigation regarding the variation of as-cast mechanical properties for secondary Al-Si based alloys (~2.5 % Cu) with a Si content varying from 4.55 to 8.90 % using the RHEOMETALTM process. The purpose was to find the most suitable Al-Si alloy for rheocasting, in comparison with the common HPDC-alloy A380 (EN-AC46000). It was found that lower Si containing alloys exhibited better elongation but slightly lower yield strength. The alloy containing 5.39 wt% Si showed the highest ultimate tensile strength in this investigation. The lower Si containing alloys also demonstrated better feedability in the rheocasting process, which is contrary to what normally is found for normal liquid casting processes. Based on the results in this investigation it is recommended to use an alloy containing about 5-7 wt% Si for rheocasting purposes.


Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1228
Author(s):  
Honglin Zhang ◽  
Zhigang Xu ◽  
Laszlo J. Kecskes ◽  
Sergey Yarmolenko ◽  
Jagannathan Sankar

The present work mainly investigated the effect of extrusion temperatures on the microstructure and mechanical properties of Mg-1.3Zn-0.5Ca (wt.%) alloys. The alloys were subjected to extrusion at 300 °C, 350 °C, and 400 °C with an extrusion ratio of 9.37. The results demonstrated that both the average size and volume fraction of dynamic recrystallized (DRXed) grains increased with increasing extrusion temperature (DRXed fractions of 0.43, 0.61, and 0.97 for 300 °C, 350 °C, and 400 °C, respectively). Moreover, the as-extruded alloys exhibited a typical basal fiber texture. The alloy extruded at 300 °C had a microstructure composed of fine DRXed grains of ~1.54 µm and strongly textured elongated unDRXed grains. It also had an ultimate tensile strength (UTS) of 355 MPa, tensile yield strength (TYS) of 284 MPa, and an elongation (EL) of 5.7%. In contrast, after extrusion at 400 °C, the microstructure was almost completely DRXed with a greatly weakened texture, resulting in an improved EL of 15.1% and UTS of 274 MPa, TYS of 220 MPa. At the intermediate temperature of 350 °C, the alloy had a UTS of 298 MPa, TYS of 234 MPa, and EL of 12.8%.


Author(s):  
Matteo Benedetti ◽  
Cinzia Menapace ◽  
Vigilio Fontanari ◽  
Ciro Santus

The present paper investigates the variability in the static and cyclic properties of two nominally identical supplies of the aeronautical Al grade 7075-T6. Samples were extracted from extruded bars of 15 mm and 60 mm diameter and with slightly different chemical composition. Noticeable differences were found in tensile strength, total elongation, low- and high-cycle fatigue strength, despite the nearly identical hardness value. The diverse mechanical behavior has been imputed to different extrusion ratio and therefore work hardening along with a more or less fine distribution of precipitates and dispersoids. The high-cycle fatigue strength was found to be in direct correlation with the monotonic yield strength and the size of the largest intermetallic precipitate. A simple equation based on Murakami sqrt(area) parameter is proposed to predict the fatigue endurance. Tensile tests and microstructural analyses are recommended instead of conventional hardness tests to have a tighter quality control on the mechanical properties of semifinished products.


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 765 ◽  
pp. 486-490 ◽  
Author(s):  
Feng Xia ◽  
Jian Ping Li ◽  
Yong Chun Guo ◽  
Zhong Yang

The microstructures and mechanical properties of an Al-Si-Cu-Mg-Ni aluminium alloy have been investigated after thermal exposure at 350 °C for time intervals up to 1000 h. Experimental results showed that, with increasing the thermal exposure time, room temperature ultimate tensile strength, elevated temperature ultimate tensile strength, and Brinell hardness firstly decreased remarkably (up to 100 h) and then decreased slightly to a certain constant value (100-1000 h). Before thermal exposure, room temperature ultimate tensile strength, elevated temperature ultimate tensile strength, elevated temperature elongation percentage, and Brinell hardness of the alloys are 203.5 MPa, 48.7 MPa, 9.2%, and 82.3, respectively. With increasing the thermal exposure time, eutectic silicon grows up steadily, and the amount of Q phase with a flower shape increases. Transmission electron microscopy analysis showed that the formation of stable θ precipitates was found in the microstructure.


Sign in / Sign up

Export Citation Format

Share Document