Scaling of intragranuiar dendritic microstructure in ingot solidification

1996 ◽  
Vol 27 (1) ◽  
pp. 101-113 ◽  
Author(s):  
D. Bouchard ◽  
J. S. Kirkaldy
Keyword(s):  
Dendritic Microstructure ◽  
Ingot Solidification

scholarly journals Effects of Weight‐Compatible Design on Ingot Solidification

2021 ◽  
Vol 92 (3) ◽  
pp. 2170031
Author(s):  
Yan Zhang ◽  
Changjun Xu ◽  
Ningning Liu ◽  
Yuting Zhang ◽  
Zhengguo Xue
Keyword(s):  
Ingot Solidification

Mechanical Properties of Equal-Channel Angular Extrusion-Processed Al-20Zn Alloy

2012 ◽  
Vol 445 ◽  
pp. 195-200
Author(s):  
Murat Aydin ◽  
Yakup Heyal
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Equal Channel Angular Extrusion ◽  
Considerable Change ◽  
Fatigue Properties ◽  
Dendritic Microstructure ◽  
Two Phase ◽  
Angular Extrusion ◽  
Alloy Increase ◽  
The Impact

The mechanical properties mainly tensile properties, impact toughness and high-cycle fatigue properties, of two-phase Al-20Zn alloy subjected to severe plastic deformation (SPD) via equal-channel angular extrusion (ECAE) using route A up to 2 passes were studied. The ECAE almost completely eliminated as-cast dendritic microstructure including casting defects such as micro porosities. A refined microstructure consisting of elongated micro constituents, α and α+η eutectic phases, formed after ECAE via route A. As a result of this microstructural change, mechanical properties mainly the impact toughness and fatigue performance of the as-cast Al-20Zn alloy increased significantly through the ECAE. The rates of increase in fatigue endurance limit are approximately 74 % after one pass and 89 % after two passes while the increase in impact toughness is 122 %. Also the yield and tensile strengths of the alloy increase with ECAE. However, no considerable change occurred in hardness and percentage elongation of the alloy. It was also observed that the ECAE changed the nature of the fatigue fracture characteristics of the as-cast Al-20Zn alloy.

Formation Mechanism of Thixotropic Microstructure of AM60 Alloy during Solidification

2014 ◽  
Vol 1030-1032 ◽  
pp. 86-89
Author(s):  
Bo Xing
Keyword(s):  
Formation Mechanism ◽  
Solid Substrate ◽  
Research Field ◽  
Primary Phase ◽  
Solid Particles ◽  
Metallographic Analysis ◽  
Semisolid Slurry ◽  
Dendritic Microstructure ◽  
Quenching Method ◽  
Semi Solid

A research field on semi-solid metal processing is the preparation of semi-solid slurry with non-dendritic microstructure. Nowadays, with the technological innovation of semi-solid slurry preparation, people turn to produce the non-dendritic semisolid microstructure by locally cooling of the alloy melt during solidification. Therefore, it is necessary to investigate the formation mechanism of the non-dendritic microstructure formation because the primary phase undergoes a specially controlled nucleation and growth which distinctly different from the commom solidification. In this paper, the semisolid slurry of AM60 alloy was produced by Self-Inoculation Method (SIM), and the microstructure evolution of primary α-Mg was investigated by water quenching method and metallographic analysis. The results indicate that the semisolid microstructure of AM60 alloy produced by SIM composed of small and globular α-Mg particles, and these grains undergone a coarsing process during quiescent holding. The solid substrate caused by the fusion of solid particles and the dendritic fragments caused by melt flow caused the grain multiplication, and then the grain undergone a steadily growth because of the uniform temperature distribution, resulting in the increase of grains density and a small grain size of the AM60 semisolid slurry.

scholarly journals Morphological transition of silicate crystals solidified from highly undercooled aerodynamically levitated melt droplets

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Ganesh Shete ◽  
Shyamprasad Karagadde ◽  
Atul Srivastava
Keyword(s):  
Magnesium Silicate ◽  
Model Material ◽  
Morphological Transition ◽  
Metallic System ◽  
Dendritic Microstructure ◽  
Contact Conditions ◽  
Cooling Rates ◽  
Morphological Transitions ◽  
Aerodynamic Levitation ◽  
Scanning Electron

AbstractThe present work reports the morphological transition during solidification of a non-metallic system. Pure magnesium silicate (Mg2SiO4) is chosen as the model material and the solidification experiments have been conducted under purely non-contact conditions using the principles of aerodynamic levitation. The influence of the undercooling and cooling rates on the surface features observed in the solidified samples is investigated. Levitation experiments have been performed for different samples, which are solidified for a range of undercooling levels between 360 to 1100° C. In order to understand and report the morphological transitions, solidified samples have been observed using scanning electron microscopy, which showed the formation of highly branched faceted microstructure for an undercooling regime of 360–800° C, and non-dendritic microstructure for even higher undercooling regime of 800–1100° C. Further experiments performed on this non-metallic system for different cooling rates also suggested that, regardless of the cooling rate, lower undercooling leads to branched faceted features, whereas higher undercooling results into unbranched facets. The methodology and instrumentation provide unique capabilities to probe the behavior of materials at high temperatures.

Evaluation of High Cycle Fatigue Properties of Double Side Welded AISI 321 Plates Using GTAW Process for Pressure Vessels

2021 ◽  
Author(s):  
Mohan Kumar S ◽  
A. Rajesh Kannan ◽  
Pramod R. ◽  
Pravin Kumar N ◽  
Nallathambi Siva Shanmugam ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Fatigue Behavior ◽  
Fatigue Behaviour ◽  
Pressure Vessels ◽  
Fatigue Properties ◽  
Dendritic Microstructure ◽  
Gas Tungsten Arc ◽  
Gtaw Process ◽  
Fatigue Rupture ◽  
Aisi 321

Abstract Titanium stabilized AISI 321 material (UNS S32100) is generally preferred in the pressure vessel industry as they are not sensitive to intergranular corrosion. In critical applications, the fatigue behaviour of weld seams are amongst the most stringent requirements. The microstructural characteristics and fatigue performance of double side welded AISI 321 plate having 6 mm thickness were evaluated in this work. AISI 321 was welded with Double side-gas tungsten arc welding (DS-GTAW) process. The fatigue behavior was examined under a loading ratio of 0.1 for two different specimens: Base metal (BM) and Weld metal (WM). Monotonic tensile results show the improved tensile properties of WM compared to BM samples. The fatigue strength of WM (332.6 MPa) was 25% higher than that of BM (265.7 MPa) specimen and is attributed to the increase in ferrite volume along with dendritic microstructure. The change in the fraction of low angle grain boundaries (LABs) and high angle grain boundaries (HABs) improved the tensile and fatigue properties. The stress amplitudes influenced the degree of striations in the BM and WM. Final fracture surfaces were characterized with dimples and micro-voids, revealing the ductile mode of fatigue fracture. The fatigue rupture surfaces of BM and WM samples at different stress regimes are discussed.

scholarly journals The Influence of Layer Thickness on the Microstructure and Mechanical Properties of M300 Maraging Steel Additively Manufactured by LENS® Technology

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 603
Author(s):  
Natalia Rońda ◽  
Krzysztof Grzelak ◽  
Marek Polański ◽  
Julita Dworecka-Wójcik
Keyword(s):  
Mechanical Properties ◽  
Layer Thickness ◽  
Maraging Steel ◽  
Structural Integrity ◽  
Tensile Tests ◽  
Dendritic Microstructure ◽  
Fine Grained ◽  
Laser Engineered Net Shaping ◽  
Microstructure And Mechanical Properties ◽  
Net Shaping

This work investigates the effect of layer thickness on the microstructure and mechanical properties of M300 maraging steel produced by Laser Engineered Net Shaping (LENS®) technique. The microstructure was characterized using light microscopy (LM) and scanning electron microscopy (SEM). The mechanical properties were characterized by tensile tests and microhardness measurements. The porosity and mechanical properties were found to be highly dependent on the layer thickness. Increasing the layer thickness increased the porosity of the manufactured parts while degrading their mechanical properties. Moreover, etched samples revealed a fine cellular dendritic microstructure; decreasing the layer thickness caused the microstructure to become fine-grained. Tests showed that for samples manufactured with the chosen laser power, a layer thickness of more than 0.75 mm is too high to maintain the structural integrity of the deposited material.

Continuous Casting of Magnesium Billets for Semi-Solid Processing

2005 ◽  
Vol 475-479 ◽  
pp. 517-520
Author(s):  
Hwa Chul Jung ◽  
Kwang Seon Shin
Keyword(s):  
Aluminum Alloys ◽  
Continuous Casting ◽  
Magnesium Alloys ◽  
Casting Process ◽  
Az91 Alloy ◽  
Attractive Alternative ◽  
Limited Information ◽  
Continuous Casting Process ◽  
Dendritic Microstructure ◽  
Semi Solid

Semi-solid processing is recognized as an attractive alternative method for the near net-shape production of engineering components. Although there has been a significant progress in semi-solid processing of aluminum alloys, very limited information is available on semi-solid processing of magnesium alloys, except for the thixomolding process. Continuous casting process has been utilized to produce the billets with the desirable cross-section at a reduced production cost for many metals, such as steel, copper and aluminum alloys. It has also been commercially utilized to produce the aluminum billets with non-dendritic microstructure for subsequent thixocasting process. However, continuous casting of magnesium billets for semi-solid processing has not yet been commercialized due to the difficulties involved in casting of magnesium alloys. In the present study, a continuous casting process has been developed for the production of the cylindrical billets of magnesium alloys for the subsequent thixocasting process. In order to obtain the desired non-dendritic microstructure with an excellent degree of homogeneity both in microstructure and composition, an electromagnetic stirring system has been utilized. A continuous casting process has been proven to be an efficient way to produce the high quality billets of magnesium alloys for semi-solid processing. A prototype air conditioner cover was produced using the continuously cast billets of AZ91 alloy.

Microstructural administered mechanical properties and corrosion behaviour of wire plus arc additive manufactured SS 321 plate

2021 ◽  
pp. 095440622110420
Author(s):  
S Mohan Kumar ◽  
R Sasikumar ◽  
A Rajesh Kannan ◽  
R Pramod ◽  
N Pravin Kumar ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Corrosion Behaviour ◽  
Film Formation ◽  
Vertical Direction ◽  
Dendritic Microstructure ◽  
Aisi 321 ◽  
Mechanical Properties And Corrosion ◽  
Corrosive Environments ◽  
Material Utilization ◽  
The Impact

Wire plus arc additive manufacturing (WAAM) technology with higher deposition rate and efficient material utilization was employed to fabricate a stainless steel 321 (SS 321) wall for the first time. In this work, the microstructural characteristics, mechanical properties and corrosion performance of as-built SS 321 were evaluated. The micrographs confirmed the presence of columnar and equiaxed dendrites along the building direction, and recrystallization of grains was noticed due to the re-melting of former layers. The microstructure was dominantly austenite with a small fraction of ferrite within the austenitic matrix. Better tensile properties were noticed for as-printed SS 321 WAAM samples in-comparison to wrought counterpart. This is corroborated to the equiaxed and columnar dendritic microstructure with small fraction of ferrite (FN). The hardness decreased from bottom (247 HV) to top (196 HV) region in SS 321 WAAM plate and is attributed to the microstructural difference with varying amount of ferrite (6.3 to 3.7 FN). The impact strength of samples in the horizontal and vertical direction was 116  ±  2 J and 114  ±  2.5 J respectively, and is comparable with the wrought AISI 321 (123  ±  1.5 J). The reduction in impact toughness is attributed to the ferrite (<6.3 FN) fraction. Polarization curves and Nyquist plots elucidate the excellent pitting resistance of SS 321 WAAM specimens, and the corrosion rate was less than 1 mils per year (mpy). Corrosion cracks were absent, and the passive film formation in the WAAM specimens were compact and highly stable for corrosive environments.

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