On The Relation between Hardness and Yield Strength in a Sand Cast AZ91 Alloy

2013 ◽  
pp. 291-294
Author(s):  
C.L. Bancroft ◽  
C.H. Cáceres ◽  
J.R. Griffiths
Keyword(s):  
Yield Strength ◽  
Az91 Alloy ◽  
Sand Cast

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.

Microstructure and Mechanical Properties of Extruded Mg-Al-Ca Based Alloys

2005 ◽  
Vol 488-489 ◽  
pp. 275-278 ◽  
Author(s):  
Rong Shi Chen ◽  
Jean Jacques Blandin ◽  
Michel Suéry ◽  
En Hou Han
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Elevated Temperature ◽  
Yield Strength ◽  
Ambient Temperature ◽  
Grain Refinement ◽  
Tensile Tests ◽  
Az91 Alloy ◽  
Microstructure And Mechanical Properties ◽  
Ca Addition

Mechanical properties and microstructure of extruded AZ91(-Ca) alloys have been studied in this paper. The results showed that Ca has no significant effect on reducing grain size of the extruded AZ91 alloy. The ambient temperature tensile tests showed that the ultimate and yield strength of extruded AZ91 alloy decreased by addition of Ca. At elevated temperature, Ca addition improves the yield strength of both AZ91 alloy. The variations in microstructure and mechanical properties of the AZ91 alloy are also discussed in terms of the effects of Ca on grain refinement and formation of constituent phases.

Improving the Microstructure and Mechanical Properties of a Cast Mg-9Al-1Zn Alloy Using Friction Stir Processing

2016 ◽  
Vol 838-839 ◽  
pp. 214-219 ◽  
Author(s):  
Wai Hoe Loke ◽  
Raafat Ibrahim ◽  
Sri Lathabai
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Processing ◽  
Intermetallic Phase ◽  
Az91 Alloy ◽  
Dendritic Microstructure ◽  
Sand Cast ◽  
Friction Stir ◽  
Microchemical Analysis ◽  
Microhardness Profile ◽  
Shear Punch Testing

Friction stir processing (FSP) is a novel thermo-mechanical technique for modifying the microstructure of metals and alloys at targeted locations. In the present study, the microstructures and mechanical properties of friction stir processed Mg-9Al-1Zn (AZ91) alloy were evaluated. 4 mm thick sand cast AZ91 plates with a coarse dendritic microstructure and visible intermetallic phase were processed using single-pass FSP with different combinations of tool rotational and traverse speeds. Significant grain refinement (<10 μm), elimination of casting defects and the dissolution of intermetallic phase were observed at the stir zone (SZ) of all tested specimens. Microhardness tests showed increased microhardness along the SZ with a more uniform microhardness profile as compared to the regions outside the SZ. Mechanical properties evaluation using shear punch testing and subsequent microstructure analysis performed using scanning electron microscopy and microchemical analysis using Energy Dispersive Spectroscopy are discussed in this paper.

Effects of La on the Microstructures and Mechanical Properties of AZ91 Magnesium Alloy and its Mechanism

2011 ◽  
Vol 328-330 ◽  
pp. 1650-1653 ◽  
Author(s):  
Jin Ling Zhang ◽  
She Bin Wang ◽  
Xiao Ye Qi ◽  
Bing She Xu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Magnesium Alloy ◽  
Yield Strength ◽  
Maximum Yield ◽  
Az91 Alloy ◽  
Strengthening Effect ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium ◽  
Maximum Yield Strength

Microstructure changes brought by the addition of La element to AZ91 magnesium alloy are studied, also, the precipitating phases were identified and their influence on the mechanical properties of alloys was investigated. Results show La makes refinement of microstructure of the AZ91 alloy, and decrease the size of Mg17Al12 phase. La element takes a priority to react with Al element over Mg, forming binary phase Al11La3 with high melting point. Certain amount of La increases tensile strength, yield strength and elongation. With more addition, La would combine more Al in matrix and decrease strengthening effect, because Al11La3 phase would become coarsening. The mechanical poroerties tests indicate that AZ91+0.16%La alloy has the best properties. Maximum tensile strength, maximum yield strength and elongation are 245MPa, 178MPa and 14.5% respective, increased by 21%, 19% and 48% respectively. The mechanism of La strenthing mechanical properties is proposed that Al11La3 phase enriched on solid-liquid interface, increased the degree of supercooling, refined the grain size and changed the crystal style.

scholarly journals The Comparison in the Microstructure and Mechanical Properties between AZ91 Alloy and Nano-SiCp/AZ91 Composite Processed by Multi-Pass Forging Under Varying Passes and Temperatures

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 625 ◽  
Author(s):  
K.B. Nie ◽  
J.G. Han ◽  
K.K. Deng ◽  
X.J. Wang ◽  
C. Xu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Yield Strength ◽  
Grain Refinement ◽  
Texture Evolution ◽  
Az91 Alloy ◽  
Strengthening Effect ◽  
Sic Nanoparticles ◽  
Microstructure And Mechanical Properties ◽  
Second Phases

In this study, both AZ91 alloy and nano-SiCp/AZ91 composite were subjected to multi-pass forging under varying passes and temperatures. The microstructure and mechanical properties of the alloy were compared with its composite. After six passes of multi-pass forging at a constant temperature of 400 ℃, complete recrystallization occurred in both the AZ91 alloy and composite. The decrease of temperature and the increase of passes for the multi-pass forging led to further refinement of dynamic recrystallized grains and dynamic precipitation of second phases. The grain size of the nano-SiCp/AZ91 composite was smaller than that of the AZ91 alloy under the same multi-pass forging condition, which indicated that the addition of SiC nanoparticles were beneficial to grain refinement by pinning the grain boundaries. The texture intensity for the 12 passes of multi-pass forging with varying temperatures was increased compared with that after nine passes. The ultimate tensile strength is slightly decreased while the yield strength was increased unobviously for the AZ91 alloy with the decrease of temperature and the increase of the passes for the multi-pass forging. Under the same condition of multi-pass forging, the yield strength of the composite was higher than that of the AZ91 alloy due to the Orowan strengthening effect and grain refinement strengthening resulting from externally applied SiC nanoparticles and internally precipitated second phases. By comparing the microstructure and mechanical properties between the AZ91 alloy and nano-SiCp/AZ91 composite, the strength-toughness properties of the composites at room temperature were affected by the matrix grain size, texture evolution, SiC nanoparticles distribution and the precipitated second phases.

Development of Mg-Al-Zn Based Diecasting Alloys for Elevated Temperature Applications

2005 ◽  
Vol 475-479 ◽  
pp. 525-528 ◽  
Author(s):  
Jeong Min Kim ◽  
Bong Koo Park ◽  
Kee Sam Shin ◽  
Joong Hwan Jun ◽  
Ki Tae Kim ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Elevated Temperature ◽  
Yield Strength ◽  
Hot Cracking ◽  
Az91 Alloy ◽  
Cracking Resistance ◽  
Microstructural Investigation ◽  
Heat Resistant ◽  
Misch Metal ◽  
Zn Content

Effort has been devoted to develop new heat resistant diecasting alloys based on Mg-Al- Zn system in this research. Small amounts of cerium-rich misch metal and antimony additions to AZ91 alloy could enhance the tensile strength at an elevated temperature while keeping the good castability. The increase of Zn content in Mg-8(wt%)Al-xZn-0.5RE-0.5Sb alloys, was observed to significantly increase the yield strength at 175oC although the castability such as fluidity and hot cracking resistance was slightly decreased. Intensive microstructural investigation on the new Mg- Al-Zn diecasting alloys was also carried out.

Effects of Quenching Rate on the Microstructures and Mechanical Properties of the Heat Treatable Mg-4.2Y-2.3Nd-1.0Gd-0.6Zr Magnesium Alloy

2015 ◽  
Vol 816 ◽  
pp. 356-361
Author(s):  
Y.H. Kang ◽  
D. Wu ◽  
Rong Shi Chen ◽  
E.H. Han
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Vickers Hardness ◽  
Cast Alloy ◽  
Age Hardening ◽  
Quenching Rate ◽  
Sand Cast ◽  
Quench Sensitivity ◽  
The Matrix ◽  
Microstructures And Mechanical Properties

The effects of quenching rate on the microstructures and mechanical properties of the heat treatable Mg-4.2Y-2.3Nd-1.0Gd-0.6Zr (wt.%) (WE43) sand-cast alloy have been studied using a combination of mechanical testing, Vickers hardness testing, optical microscopy (OM) and scanning electron microscope (SEM). Two quenching conditions, either air quenching or 60°C water quenching, were employed. The results indicate that some precipitates have formed in the matrix and grain boundaries in the air-quenched solutionized alloy. And the Vickers hardness and yield strength (YS) is HV77 and 155 MPa, respectively, which is slightly more than the 60°C water-quenched solutionized alloy. However, the ultimate tensile strength (UTS) and yield strength (YS) of the peak-aged at 250°C (T6) of the two quenching conditions are both 273 MPa and 212 MPa, respectively. And they have similar age hardening curves at 250°C and the T6 microstructure. So the results indicate that in this work of quenching rate range WE43 alloy has few quench sensitivity effect.

Evaluation of an Alternate Method for Determining Yield Strength Offset Values for Selective Laser Sintered Polymeric Materials

2019 ◽  
Author(s):  
Chelsey Henry ◽  
Keith Rupel ◽  
Charles Park ◽  
Joseph Costanzo ◽  
Cary Kaczowka ◽  
...  
Keyword(s):  
Yield Strength ◽  
Polymeric Materials

Influence of Yield Strength Variability over Cross-Section to Steel Beam Load-Carrying Capacity

2005 ◽  
Vol 10 (2) ◽  
pp. 151-160 ◽  
Author(s):  
J. Kala ◽  
Z. Kala
Keyword(s):  
Yield Strength ◽  
Cross Section ◽  
Carrying Capacity ◽  
Bending Moment ◽  
Statistical Characteristics ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Strength Variability ◽  
Hot Rolled ◽  
Hot Rolled Steel

Authors of article analysed influence of variability of yield strength over cross-section of hot rolled steel member to its load-carrying capacity. In calculation models, the yield strength is usually taken as constant. But yield strength of a steel hot-rolled beam is generally a random quantity. Not only the whole beam but also its parts have slightly different material characteristics. According to the results of more accurate measurements, the statistical characteristics of the material taken from various cross-section points (e.g. from a web and a flange) are, however, more or less different. This variation is described by one dimensional random field. The load-carrying capacity of the beam IPE300 under bending moment at its ends with the lateral buckling influence included is analysed, nondimensional slenderness according to EC3 is λ¯ = 0.6. For this relatively low slender beam the influence of the yield strength on the load-carrying capacity is large. Also the influence of all the other imperfections as accurately as possible, the load-carrying capacity was determined by geometrically and materially nonlinear solution of very accurate FEM model by the ANSYS programme.

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