scholarly journals Excellent age hardenability with the controllable microstructure of AXW100 magnesium sheet alloy

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sumi Jo ◽  
Lawrence Whitmore ◽  
Sangkyu Woo ◽  
Ainhoa Urrutia Aramburu ◽  
Dietmar Letzig ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Texture Evolution ◽  
Grain Structure ◽  
Aged Condition ◽  
Tem Analysis ◽  
Fine Grain ◽  
Peak Aged Condition ◽  
Peak Aged ◽  
Grain Boundary Pinning ◽  
Weak Texture

AbstractAge-hardenability and corresponding improvement of the mechanical properties of Mg–1Al–0.7Ca and Mg–1Al–0.7Ca–0.7Y alloy sheets are addressed with respect to the microstructure and texture evolution during thermomechanical treatments. A fine grain structure and weak texture with the basal pole split into the sheet transverse direction are retained in the Mg–1Al–0.7Ca–0.7Y sheet even after the homogenization at 500 °C, due to the grain boundary pinning by Y-containing precipitates possessing a high thermal stability. Contrarily, the Mg–1Al–0.7Ca sheet shows a coarse microstructure and basal-type texture after the homogenization. The peak-aged condition is attained after the aging at 250 °C for 1800 s of both homogenized sheets, while the Y-containing sheet shows a higher hardness than the Mg–1Al–0.7Ca sheet. TEM analysis and thermodynamic calculation show the formation of metastable precipitates composed of Al, Ca, Y and Mg in the Mg–1Al–0.7Ca–0.7Y sheet at the homogenized and peak-aged conditions. A significant increase in the yield strength is obtained in the peak-aged condition from 162 MPa after the homogenization to 244 MPa, which arises from the increased size and number density of the precipitates. The high age-hardenability of the Mg–1Al–0.7Ca–0.7Y sheet attributes to the superior mechanical properties with an improved ductility promoted by the weak texture.

Study on Orange Peel Phenomena in Cu-Cr-Zr-Ti Alloy Thrust Chamber

2015 ◽  
Vol 830-831 ◽  
pp. 362-366
Author(s):  
Ravi Ranjan Kumar ◽  
Alok Singh ◽  
Ashish Kumar Pande ◽  
Debasis Tripathy ◽  
M. Amruth ◽  
...  
Keyword(s):  
Grain Size ◽  
Orange Peel ◽  
Grain Structure ◽  
Coarse Grain ◽  
Air Cooling ◽  
Rocket Engines ◽  
Aged Condition ◽  
Thrust Chamber ◽  
Peak Aged Condition ◽  
Peak Aged

Cu-Cr-Zr-Ti alloys are widely used for fabrication of thrust chamber in liquid rocket engines, because of their high thermal conductivity and adequate strength. The alloy should be used in peak aged condition to achieve the best combination of strength and conductivity. However, realization of final component involves different stages of forming, intermediate heat treatment and brazing operations, which limit the usage of the alloy in peak aged condition. The formability of material depends on grain size to a large extent. Larger grained metals have better formability, but the roughened surface that results from stretching metal with coarse grain structure results in surface defects like orange peel. Copper alloys on cold working sometimes exhibit a surface pebbling effect termed as ‘orange peel’ or alligator skin’.The plates of this copper alloy, finish hot rolled at 925 to 975°C and annealed at 980±10°C for 10 ±2 min followed by air cooling are subjected to different stages of forming to get the final profile of thrust chamber. During the course of forming of plate for divergent thrust chamber, orange peel defect is observed in areas of higher deformation. Detailed characterization of these formed shells in terms of microstructure, grain size and mechanical property has been carried out to find out the exact cause of this defect. Study revealed that the plate has coarse grain structure, which has resulted in orange peel defect during forming. To overcome this effect, the plates were realized with modifications in finish hot rolling and annealing temperatures, which has shown improvement in grain refinement and mechanical properties. It has suppressed the orange peel defect during forming.

Effect of Simulated Brazing Cycle on the Microstructure and Mechanical Properties of Cu-Cr-Zr-Ti Alloy

2012 ◽  
Vol 710 ◽  
pp. 626-631 ◽  
Author(s):  
S. Chenna Krishna ◽  
K.V. Radhika ◽  
K. Thomas Tharian ◽  
G. Sudarshan Rao ◽  
M. Swathi Kiranmayee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hardness Measurement ◽  
Rocket Engines ◽  
Aged Condition ◽  
Thrust Chamber ◽  
Microstructure And Mechanical Properties ◽  
Liquid Rocket Engines ◽  
Peak Aged Condition ◽  
Peak Aged ◽  
Liquid Rocket

Cu-Cr-Zr-Ti alloys are widely used for fabrication of thrust chamber in liquid rocket engines, because of their high thermal conductivity and adequate strength. The alloy should be used in peak-aged condition to achieve the best combination of strength and conductivity. However, realization of final component involves forming and brazing operations which limit the usage of the alloy in peak aged condition. Therefore, an attempt has been made to study the effect of the simulated brazing treatment on the microstructure and mechanical properties using optical microscopy, electron microscopy, mechanical testing and hardness measurement. The high temperature brazing treatments resulted in tremendous grain growth. The measured hardness is observed to be in line with the grain size of the specimens. The hardness and tensile strength decreased in samples subjected to simulated brazing cycle, implying requirement for a post braze treatment. After the post brazing treatment the optimum mechanical properties have been achieved at room temperature. Low ductility was observed at 600°C in the samples subjected to simulated brazing cycle.

Production of Fine-Grained and Weak Texture Structure in an Mg-7Gd-5Y-1Nd-0.5Zr Alloy by Multi-Axial Forging

2014 ◽  
Vol 633-634 ◽  
pp. 120-124
Author(s):  
Ting Li ◽  
Kui Zhang ◽  
Zhi Wei Du ◽  
Jia Wei Yuan ◽  
Xing Gang Li
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Texture Evolution ◽  
Ultrafine Grain ◽  
Fine Grained ◽  
Fine Grain ◽  
Ultrafine Grain Size ◽  
Refinement Mechanism ◽  
Texture Structure ◽  
Weak Texture

Multi-axial forging was employed to produce simultaneously ultrafine grain size and weak texture in an Mg-7Gd-5Y-1Nd-0.5Zr alloy. The results indicate that the structure of fine grain size and weak texture could be achieved after two cycles of multi-axial forging, which leads to a substantial mechanical properties improvement. The grain refinement mechanism and texture evolution of Mg-7Gd-5Y-1Nd-0.5Zr alloy during multi-axial forging have been investigated.

Microstructure and Mechanical Properties of the Spray-Deposited Al-10.8Zn-2.8Mg-1.9Cu Alloy at Various Aging Conditions

2007 ◽  
Vol 561-565 ◽  
pp. 809-812
Author(s):  
Feng Wang ◽  
Bai Qing Xiong ◽  
Yon Gan Zhang ◽  
Bao Hong Zhu ◽  
Hong Wei Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Resolution Electron Microscopy ◽  
Tensile Tests ◽  
Aged Condition ◽  
Aging Condition ◽  
Microstructure And Mechanical Properties ◽  
Peak Aged Condition ◽  
Resolution Electron ◽  
Aging Conditions ◽  
Peak Aged

In this paper, Al-10.8Zn-2.8Mg-1.9Cu alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray deposited alloy at various aging conditions (T6, T73 and RRA treatment) were studied using high-resolution electron microscopy, selected area diffraction, and tensile tests. The results indicate that the two types of GP zones, GPI and GPII zones are major precipitates for the alloy under peak-aged condition. The peak UTS and YS values achieved at an ageing temperature of 120 °C was 818 MPa and 793 MPa. Under two-step aging condition, the GP zones and η’ are major precipitates for the alloy, the discontinuous grain boundary precipitates are favorable to SCC resistance in over-aged condition, which reduces its strength 58 MPa(about 7%) comparing to the peak-aged condition. RRA treatment decreased ultimate tensile strength 25 MPa (about 3%) in values compared with the alloy at T6 condition.

Aging Behavior in 15-5 PH Precipitation Hardening Martensitic Stainless Steel

2012 ◽  
Vol 710 ◽  
pp. 483-488 ◽  
Author(s):  
V. Anil Kumar ◽  
M.K. Karthikeyan ◽  
Rohit Kumar Gupta ◽  
F. Gino Prakash ◽  
P. Ram Kumar
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Precipitation Hardening ◽  
Martensitic Stainless Steel ◽  
Low Carbon ◽  
Aged Condition ◽  
Aging Behavior ◽  
Peak Aged Condition ◽  
Peak Aged

15-5 PH stainless steel is strengthened by precipitation of copper rich phases in a low carbon body centred cubic (b.c.c) lath martensitic matrix. Microstructures developed in aerospace grade 15-5PH precipitation-hardened stainless steel with different aging heat treatments have been studied. An attempt has been made to correlate the microstructural observations with the mechanical properties in different aging regimes. The overaging treatment imparts excellent ductility with a compromise in strength in peak aged condition to overaged condition the tune of 300 MPa in both tensile and yield strength. Hardness and tensile strength showed a similar decreasing trend with increase in aging temperature.

scholarly journals Texture Evolution in AA6082-T6 BFSW Welds: Optical Microscopy and EBSD Characterisation

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3215 ◽  
Author(s):  
Abbas Tamadon ◽  
Dirk J. Pons ◽  
Don Clucas ◽  
Kamil Sued
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Optical Microscopy ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
Grain Structure ◽  
Friction Stir ◽  
Fine Grain ◽  
Grain Structures ◽  
Dynamic Recrystallisation

One of the difficulties with bobbin friction stir welding (BFSW) has been the visualisation of microstructure, particularly grain boundaries, and this is especially problematic for materials with fine grain structure, such as AA6082-T6 aluminium as here. Welds of this material were examined using optical microscopy (OM) and electron backscatter diffraction (EBSD). Results show that the grain structures that form depend on a complex set of factors. The motion of the pin and shoulder features transports material around the weld, which induces shear. The shear deformation around the pin is non-uniform with a thermal and strain gradient across the weld, and hence the dynamic recrystallisation (DRX) processes are also variable, giving a range of observed polycrystalline and grain boundary structures. Partial DRX was observed at both hourglass boundaries, and full DRX at mid-stirring zone. The grain boundary mapping showed the formation of low-angle grain boundaries (LAGBs) at regions of high shear as a consequence of thermomechanical nature of the process.

scholarly journals The Mechanical Properties of AlSi17Cu5 Cast Alloy after Overheating and Modification of CuP Master Alloy

2013 ◽  
Vol 13 (3) ◽  
pp. 68-71
Author(s):  
J. Piątkowski ◽  
M. Jabłońska
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Master Alloy ◽  
Liquid State ◽  
Alloy Composition ◽  
Cast Alloy ◽  
Primary Silicon ◽  
Grain Structure ◽  
Silicon Crystals ◽  
Fine Grain

Abstract The paper presents the results of studies on the effect of the AlSi17Cu5 alloy overheating to atemperature of 920°C and modification with phosphorus (CuP10) on the resultingmechanical (HB, Rm, R0.2) and plastic (A5 and Z) properties. It has been shown that, so-called, "timethermal treatment" (TTT) of an alloy in the liquid state, consisting inoverheating the metal to about 250°C above Tliq,holding at this temperature by 30 minutes improvesthe mechanical properties. It has also been found that overheating of alloy above Tliq.enhances the process of modification, resulting in the formation of fine-grain structure. The primary silicon crystals uniformly distributed in the eutectic and characteristics ofthe α(Al) solution supersaturated with alloying elements present in the starting alloy composition (Cu, Fe) provide not only an increase of strength at ambient temperature but also at elevated temperature (250°C).

Evolution of Microstructure and Mechanical Properties of the Thixo-Diecast 319s Alloy during Heat Treatment

2013 ◽  
Vol 765 ◽  
pp. 511-515 ◽  
Author(s):  
Da Quan Li ◽  
Xiao Kang Liang ◽  
Fu Bao Yang ◽  
You Feng He ◽  
Fan Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Cast Alloy ◽  
Grain Structure ◽  
Precipitate Size ◽  
Fine Grain ◽  
Microstructure And Mechanical Properties ◽  
Optimum Heat ◽  
Evolution Of Microstructure

The evolution of microstructure and mechanical properties during solution and ageing heat treatment process was studied in terms of a thixo-diecast impeller of 319s aluminium alloy. The cast alloy exhibited a microstructure consisting of primary uniformly distributed in α-Al globules and the eutectics. A series of heat treatment studies were performed to determine optimum heat treatment parameters, in order to achieve fine grain structure, fine silicon particles and optimal precipitate size and distribution. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to study the evolution of microstructure and mechanical properties. The results demonstrate that, the full T6 heat treatments are successfully applied to thixo-diecast 319s impellers. A two-step solution heat treatment is employed to prevent porosity due to overheating. The tensile properties of thixo-diecast 319s impellers were substantially enhanced after T6 heat treatment. The plate-shaped θ′ precipitates and lath-shaped Q′ precipitates are the most effective for precipitation strengthening.

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