The Preparation of Rapidly Solidified and Powder Metallurgy AZ91 Alloy

2012 ◽  
Vol 476-478 ◽  
pp. 29-33
Author(s):  
Shao Ding Sheng ◽  
Hong Ge Yan
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Alloy Powder ◽  
Optical Microscope ◽  
Az91 Alloy ◽  
Precipitated Phase ◽  
Precipitated Phases ◽  
Rapidly Solidified ◽  
Equiaxed Grains

AZ91 alloy powder was prepared by two-roller quenching equipment. The powders were consolidated and extruded into bar. The microstructures of the powders and bars were observed by optical microscope (OM), XRD, HRTEM and SEM. The results suggested that the grain size of the powder were equiaxed with the sizes of about 1~5μm. The as-extruded alloy bars retain equiaxed grains with a large number of precipitated phases, β-Al12Mg17 and AlMg2Zn. The alloy exhibited excellent mechanical properties, the ultimate and yield tensile strength were 383.2MPa and 275.1MPa respectively. The shape of the precipitated phase was approximately globular with the size of about 50~200nm.

scholarly journals Microstructure, and Mechanical and Wear Properties of Grp/AZ91 Magnesium Matrix Composites

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1190 ◽  
Author(s):  
Chang-rui Wang ◽  
Kun-kun Deng ◽  
Yan Bai
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Yield Strength ◽  
Wear Mechanism ◽  
Thermal Deformation ◽  
Volume Fraction ◽  
Az91 Alloy

Based on semi-solid mixing technology, two kinds of as-cast Grp (Graphite particles)/AZ91 composites with different Grp volume fractions (5 vol %, 10 vol %) were prepared; these are called 5 vol % Grp/AZ91 composites and 10 vol % Grp/AZ91 composites, respectively. In order to eliminate casting defects, refine grains, and improve mechanical properties, thermal deformation analysis of these composites was conducted. The effect of the addition of Grp and thermal deformation on the microstructure, mechanical properties, and wear resistance of AZ91 composite was explored. The results showed that after 5 vol % Grp was added into the as-cast AZ91 alloy, Mg17Al12 phases were no longer precipitated reticularly along the grain boundary, and Al4C3 phases were formed inside the composite. With the increase in the volume fraction of Grp, the grains of the AZ91 composites were steadily refined. With the increase of forging pass, the grain size of 5% Grp/AZ91 composites decreased first, and then increased. Additionally, the Grp size decreased gradually. There was little change in the yield strength, and the tensile strength and elongation were improved to a certain extent. After forging and extrusion of 5% Grp/AZ91 composites once, the grain size and Grp size were further reduced, and the yield strength, tensile strength, and elongation were increased by 23%, 30%, and 65%, respectively, compared with the composite after forging. With the increase of the number of forging passes before extrusion, the grain size decreased little by little, while the Grp size remained unchanged. The average yield strength, tensile strength, and elongation of the composites after forging and extrusion six times were increased by 3%, 3%, and 23%, respectively, compared with the composite after forging and extrusion once. The wear rate and friction coefficient of the 5% Grp/AZ91 composites decreased after forging once, and the wear mechanism was mainly due to ploughing wear. By comparison, the wear rate and friction coefficient of the 5% Grp/AZ91 composites increased in the extrusion state, and the main wear mechanism was from wedge formation and micro-cutting wear.

Influence of Grain Size on Mechanical Properties in a Fe-9Ni-12Mn-2.5Si-1.0C TWIP Steel

2011 ◽  
Vol 197-198 ◽  
pp. 655-661
Author(s):  
Ze Bin Yang ◽  
Ding Yi Zhu ◽  
Wei Fa Yi ◽  
Shu Mei Lin ◽  
Cheng Mei Du
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Strain Hardening ◽  
Twip Steel ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Microstructure Observation ◽  
Transmission Electron ◽  
Average Grain Size

We investigate the influence of grain size on mechanical properties in a Fe-9Ni-12Mn-2.5Si-1.0C TWIP steel by unidirectional tensile. Meanwhile the microstructures of the TWIP steel were observed and analyzed by optical microscope (OM) and transmission electron microscope (TEM). The experimental results show that the TWIP steel’s yield strength and tensile strength decrease with the increasing of grain size, whereas the plasticity increases with it. When the average grain size reaches to 27μm, the tensile strength is 1080MPa, the elongation percentage is 77%, and the strength-plasticity product achieves the 83160MPa•%. Steel’s strain hardening rate can be changed from three-stage to four-stage with the increasing of grain sizes, the areas of strain hardening by twin deformation mechanism are expanded. Through the microstructure observation we found that, coarse-grained TWIP steel conducts to twinning formation, the high density twins can increase the alloy’s ductility by splitting the grain.

Effects of Sr and B addition on microstructure and mechanical properties of AZ91 magnesium alloy

2007 ◽  
Vol 22 (9) ◽  
pp. 2423-2428 ◽  
Author(s):  
H.L. Zhao ◽  
S.K. Guan ◽  
F.Y. Zheng
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Solidification Range ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size ◽  
B Additions ◽  
Az91 Magnesium

The effects of Sr and B addition on the microstructure and mechanical properties of AZ91 alloy were studied. The results of this work show that a small amount of Sr addition to AZ91 refined the grain size. The highest tensile strength was obtained from the alloy with the optimal composition of 0.5% Sr and 0.09% B added, in which the average grain size was 42 μm. The tensile strength and elongation of the AZ91–0.5%Sr–0.09%B alloy were 151 MPa and 1.62%, respectively. Some needle-shaped Al4Sr particles distributed mainly at grain boundaries have been observed in the alloys with Sr and B additions. The fluidity is improved significantly, and the solidification range decreased by adding Sr and B. The liquidus of AZ91 alloy decreased markedly with the addition of Sr and B, but the solidus hardly changed. Therefore, the solidification range can be decreased, which will improve the die-casting properties.

Influence of Ti to the Microstructure and Mechanical Properties of Al-12Si-3.2Cu-1Mg-2.4Ni Piston Alloy

2013 ◽  
Vol 477-478 ◽  
pp. 1278-1283
Author(s):  
Ling Zhan Zhou ◽  
Yin Jiang Peng ◽  
Xiu Rong Zhu ◽  
Guang Ming Zhang ◽  
Li Ming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Squeeze Casting ◽  
Casting Process ◽  
Optical Microscope ◽  
Heat Treated ◽  
Eutectic Si ◽  
Squeeze Casting Process ◽  
Ti Addition

Al-12Si-3.2Cu-1Mg-2.4Ni-χTi (χ=0, 0.2) alloys were prepared by squeeze casting process, and then heat-treated. The mechanical properties were tested at 350°C, the microstructure and phases in them were investigated by optical microscope, SEM, EDS and XRD. It is found that the grain size has an obvious increment after 0.2 wt. % Ti additions to Al-12Si-3.2Cu-1Mg-2.4Ni, and the ultimate tensile strength at elevated-temperature increased accordingly. Intermetallic compounds, such as γ-Al7Cu4Ni, M-Mg2Si, Q-Al5Cu2Mg8Si6 and δ-Al3CuNi existing in alloys with and without Ti addition. Needle-like Ti containing phase with the elements of Al, Si and Ti created in Al-12Si-3.2Cu-1Mg-2.4Ni-0.2Ti alloy, and the eutectic Si is found to distribute by the side of Ti containing phase.

Effect of Mg Addition on the Mechanical Properties of Rapidly Solidified Al-Mn Alloys at Elevated Temperatures

2010 ◽  
Vol 638-642 ◽  
pp. 339-344
Author(s):  
Makoto Sugamata ◽  
Akio Tomioka ◽  
Yousuke Kubota
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Tensile Strength ◽  
Intermetallic Compounds ◽  
Elevated Temperatures ◽  
Optical Microscope ◽  
Strength Increase ◽  
Positive Effects ◽  
Uniform Dispersion ◽  
Rapidly Solidified

With an aim of clarifying the strength of rapidly solidified P/M materials strengthened by solid solution of Mg and dispersion of transition metal compounds at elevated temperature, Al-2mass%Mn, Al-4mass%Mn and Al-6mass%Mn alloys with varied Mg additions of 0, 1 and 3 mass% were prepared by rapid solidification techniques. Rapidly solidified (RS) flakes were produced by remelting alloy ingots in a graphite crucible, atomizing the alloy melt and subsequent splat-quenching on a rotating water-cooled copper roll under argon atmosphere.　The RS flakes were consolidated to the P/M materials by hot extrusion after vacuum degassing. Cast ingots of these alloys were also hot-extruded under the same conditions to the I/M as reference materials. Metallographic structures and constituent phases were studied for the P/M and I/M materials by optical microscope and X-ray diffraction. Mechanical properties of as-extruded and annealed P/M materials and as-extruded I/M materials were examined by tensile test at room and elevated temperatures under various strain rates. Uniform dispersion of fine intermetallic compounds (Al6Mn) was observed in all the as-extruded P/M materials. Added Mg was present as the solute in I/M and P/M materials alloy even after annealing. The P/M materials containing Mg exhibited higher hardness and strength at room temperature, than those without Mg. It was considered that both solid solution of Mg and dispersion of intermetallic compounds were contributing the hardness and strength increase in the rapidly solidified Al-Mn-Mg alloys. Tensile strength increases with increasing amount of Mg in I/M materials at all testing temperatures. However, strength of as-extruded P/M materials decreases with addition of Mg at 573K and 673K. Thus the positive effects of Mg additions on tensile strength of as-extruded P/M materials disappeared at higher testing temperature. Tensile strength of annealed P/M materials in which dislocation density decreased and compound particle coarsened increased with addition of Mg at elevated temperatures.

Influence of Extrusion Temperature on Microstructures and Properties of Cu-17Ni-3Al-X Alloy

2013 ◽  
Vol 749 ◽  
pp. 105-111
Author(s):  
Wei Yan ◽  
Yuan Hui Weng ◽  
Zong Qiang Luo ◽  
Wei Wen Zhang
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Brinell Hardness ◽  
Cast Alloy ◽  
Hot Extrusion ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Different Temperatures ◽  
Electronic Microscope

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.

Influence of Extrusion Ratio on Microstructures and Properties of Cu-17Ni-3Al-X Alloy

2013 ◽  
Vol 477-478 ◽  
pp. 1307-1315 ◽  
Author(s):  
Yuan Hui Weng ◽  
Yuan Xuan Liu ◽  
Tan Wei ◽  
Wei Wen Zhang ◽  
Zong Qiang Luo
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Brinell Hardness ◽  
Cast Alloy ◽  
Optical Microscope ◽  
Extrusion Ratio ◽  
Hardness Testing ◽  
Second Phases ◽  
Microstructures And Mechanical Properties

The microstructures and mechanical properties of the Cu-17Ni-3Al-X alloy hot-extruded at different extrusion ratios were investigated by tensile and hardness testing, optical microscope (OM) and scanning electronic microscope.The results show that the dynamic re-crystallization occurs when the extrusion ratio λ increases from 8 to 25. The grain size and the second phases of the extruded alloys are obviously finer than that of the as-cast alloy. The mechanical properties of the extruded alloys are improved remarkably. The alloy with the λ of 25 obtained the tensile strength of 1025MPa, Brinell Hardness of 312HB and elongation of 10.0% which is 35%, 14% and 355%, respectively, higher than that of the as-cast alloy.

INFLUENCE OF T5 TREATMENT ON MICROSTRUCTURE AND PROPERTIES OF EXTRUDED ZK60 MAGNESIUM ALLOY

2009 ◽  
Vol 23 (06n07) ◽  
pp. 996-1001 ◽  
Author(s):  
ZHIMIN ZHANG ◽  
BAOHONG ZHANG
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Magnesium Alloy ◽  
Yield Strength ◽  
Experimental Results ◽  
Second Phase ◽  
Microstructure And Properties ◽  
Precipitated Phase ◽  
Zk60 Magnesium Alloy

As-cast ZK60 magnesium alloy that has been treated by homogenizing was forward extruded at 380°C and different extrusion ratios. Half of the extruded samples were treated by T5 treatment (10 hours at 170°C). The microstructure and mechanical properties of extruded samples that have been treated by T5 treatment and not been treated by T5 treatment have been measured. Experimental results show that the T5 treatment of extruded ZK60 magnesium alloy will cause the tensile strength and hardness to increase in some sort, the yield strength to increase obviously, but elongation to decrease slightly. When ZK60 magnesium alloy is extruded at 380°C, the second phase, MgZn and a small quantity of MnZn 2, will precipitate, and the distribution of second phase is even and dispersed. After T5 treatment, the change of grain size is not obvious, but the quantity of precipitated phase obviously increases comparing with extruded samples, and some of the precipitated phase aggregate and grow.

Vibratory weld conditioning during gas tungsten arc welding of al 5052 alloy on the mechanical and micro-structural behavior

2020 ◽  
Vol 17 (6) ◽  
pp. 831-836
Author(s):  
M. Vykunta Rao ◽  
Srinivasa Rao P. ◽  
B. Surendra Babu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Welded Joints ◽  
Great Influence ◽  
Welding Process ◽  
Microstructural Characterization ◽  
Content Type ◽  
Average Grain Size

Purpose Vibratory weld conditioning parameters have a great influence on the improvement of mechanical properties of weld connections. The purpose of this paper is to understand the influence of vibratory weld conditioning on the mechanical and microstructural characterization of aluminum 5052 alloy weldments. An attempt is made to understand the effect of the vibratory tungsten inert gas (TIG) welding process parameters on the hardness, ultimate tensile strength and microstructure of Al 5052-H32 alloy weldments. Design/methodology/approach Aluminum 5052 H32 specimens are welded at different combinations of vibromotor voltage inputs and time of vibrations. Voltage input is varied from 50 to 230 V at an interval of 10 V. At each voltage input to the vibromotor, there are three levels of time of vibration, i.e. 80, 90 and 100 s. The vibratory TIG-welded specimens are tested for their mechanical and microstructural properties. Findings The results indicate that the mechanical properties of aluminum alloy weld connections improved by increasing voltage input up to 160 V. Also, it has been observed that by increasing vibromotor voltage input beyond 160 V, mechanical properties were reduced significantly. It is also found that vibration time has less influence on the mechanical properties of weld connections. Improvement in hardness and ultimate tensile strength of vibratory welded joints is 16 and 14%, respectively, when compared without vibration, i.e. normal weld conditions. Average grain size is measured as per ASTM E 112–96. Average grain size is in the case of 0, 120, 160 and 230 is 20.709, 17.99, 16.57 and 20.8086 µm, respectively. Originality/value Novel vibratory TIG welded joints are prepared. Mechanical and micro-structural properties are tested.

scholarly journals Investigation of Damage Evolution in Heterogeneous Rock Based on the Grain-Based Finite-Discrete Element Model

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3969
Author(s):  
Shirui Zhang ◽  
Shili Qiu ◽  
Pengfei Kou ◽  
Shaojun Li ◽  
Ping Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Grain Orientation ◽  
Damage Evolution ◽  
Discrete Element ◽  
Uniaxial Tensile ◽  
Tensile Cracks ◽  
Rock Heterogeneity ◽  
Heterogeneous Rock

Granite exhibits obvious meso-geometric heterogeneity. To study the influence of grain size and preferred grain orientation on the damage evolution and mechanical properties of granite, as well as to reveal the inner link between grain size‚ preferred orientation, uniaxial tensile strength (UTS) and damage evolution, a series of Brazilian splitting tests were carried out based on the combined finite-discrete element method (FDEM), grain-based model (GBM) and inverse Monte Carlo (IMC) algorithm. The main conclusions are as follows: (1) Mineral grain significantly influences the crack propagation paths, and the GBM can capture the location of fracture section more accurately than the conventional model. (2) Shear cracks occur near the loading area, while tensile and tensile-shear mixed cracks occur far from the loading area. The applied stress must overcome the tensile strength of the grain interface contacts. (3) The UTS and the ratio of the number of intergrain tensile cracks to the number of intragrain tensile cracks are negatively related to the grain size. (4) With the increase of the preferred grain orientation, the UTS presents a “V-shaped” characteristic distribution. (5) During the whole process of splitting simulation, shear microcracks play the dominant role in energy release; particularly, they occur in later stage. This novel framework, which can reveal the control mechanism of brittle rock heterogeneity on continuous-discontinuous trans-scale fracture process and microscopic rock behaviour, provides an effective technology and numerical analysis method for characterizing rock meso-structure. Accordingly, the research results can provide a useful reference for the prediction of heterogeneous rock mechanical properties and the stability control of engineering rock masses.

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