Relationship of DAS to cooling rate in solidified U-700 alloy

1986 ◽  
Vol 5 (12) ◽  
pp. 1273-1274 ◽  
Author(s):  
Prakash Khedkar ◽  
Philip Nash
Keyword(s):  
Cooling Rate ◽  
Relationship Of

Effects of Solidification Parameters on SDAS of A357 Alloy

2008 ◽  
Vol 51 ◽  
pp. 85-92 ◽  
Author(s):  
Juan He ◽  
Jian Min Zeng ◽  
Along Yan
Keyword(s):  
Cooling Rate ◽  
Solidification Time ◽  
Local Solidification Time ◽  
A357 Alloy ◽  
Solidification Condition ◽  
Alloy Casting ◽  
Furan Resin ◽  
Solidification Parameters ◽  
Relationship Of ◽  
The Relationship

In this investigation, experiments were carried out to study the relationship of solidification parameters and the secondary dendrite arm spacing (SDAS) in A357 alloy casting with various thicknesses under the same solidification condition. The results show that the cooling rate decreases as the thickness of specimens increases, the local solidification time increased, and SDAS increased. The relationships between the SDAS and cooling rate and local solidification time under the condition of furan resin self-hardening sand casting were obtained: SDAS = 20.8 tf 0.3, SDAS = 69.34 v -0.3. The mechanical properties have some linear relations with SDAS of A357 alloy after aging heat treatment. The correlations can be expressed: UTS=410.4-0.8SDAS and El%=7.9-0.05SDAS.

Numerical Evaluation on the Curve Deviation of the Molded Glass Lens

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Jian Zhou ◽  
Mujun Li ◽  
Yang Hu ◽  
Tianyi Shi ◽  
Yueliang Ji ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Good Reason ◽  
Processing Parameters ◽  
Forming Process ◽  
Molding Process ◽  
Contact Heat ◽  
Thermal Boundary Conditions ◽  
Glass Lens ◽  
Final Profile ◽  
Relationship Of

The compression molding of precision glass lens is a near net-shape forming process for optical components fabrication. The final profile curve accuracy is one of the most crucial criterions for evaluating the quality of the molded lens. In this research, our purpose was focused on the evaluation of the molded lens curve deviation. By incorporating stress relaxation and structural relaxation model of glass, numerical simulations of the whole molding process for fabricating a planoconvex lens were conducted by utilizing the commercial software msc Marc. The relationship of the three variables, i.e., the lens curve deviation, the mold curve deviation, the gap between the lens and the lower mold, was discussed and the evolution plots with time of the three variables were obtained. Details of the thermal boundary conditions were discussed by considering the contact heat transfer behavior. Then the essentiality of a small gap between the molds and the molded lens after releasing the upper mold was demonstrated. In details, the sensitivity analysis of the processing parameters was conducted, such as the releasing temperature, the cooling rate in the annealing and fast cooling stage, respectively, and the magnitude of the hold-up force. The results showed that the glass lens curve deviation was not sensitive to the choices of the releasing temperature and the cooling rate. What's more, the results indicated that the curve deviation decreased with the hold-up force increasing. Finally, with all the details considered, the final simulation results were presented accurately with good reason.

Effect of the Crystallization Conditions on the Epitaxial Relationship of Si Deposited on 3C-SiC(100)

2006 ◽  
Vol 527-529 ◽  
pp. 1563-1566 ◽  
Author(s):  
Gabriel Ferro ◽  
Efstathios K. Polychroniadis ◽  
D. Panknin ◽  
Wolfgang Skorupa ◽  
J. Stoemenos ◽  
...  
Keyword(s):  
Melting Point ◽  
Cooling Rate ◽  
Deposition Temperature ◽  
Lattice Mismatch ◽  
Thin Layers ◽  
Liquid Droplets ◽  
Epitaxial Relationship ◽  
Free Standing ◽  
Crystallization Conditions ◽  
Relationship Of

The epitaxial relationship of Si deposited on 3C-SiC was studied using both free standing 3C-SiC(100) material from Hoya and 3C-SiC thin layers deposited on Si(100) as substrates. The conditions of Si growth were varied depending on the substrate. When Si is deposited at 1000°C on (001) 3C-SiC, it is in perfect epitaxial relation with the SiC layer [100]Si//[100]SiC and [001]Si//[001]SiC. After a 20 ms flash lamp pulse on the same sample, which has the effect of fast melting of the Si top layer only, the defects in the Si are eliminated. Using free standing 3C-SiC, the deposition temperature was not limited by the Si melting point so that it was fixed at 1500°C in order to form a set of Si liquid droplets on the surface with diameters ranging from 5 to 20 μm. Surprisingly more than 60% of the Si droplets exhibit the epitaxial relation [110]Si//[001]SiC and [111]Si//[110]SiC after crystallization. The occurrence of this epitaxial relationship can be understood in terms of lattice mismatch reduction from 20% to 18.3%. The conditions of crystallization, most probably the cooling rate, seem to have a strong effect on Si orientation.

Effect of Cooling and Isothermal Aging on Microstructure Using Electroless Nickel (Boron) Plating

2014 ◽  
Vol 695 ◽  
pp. 352-356
Author(s):  
Hardinna Wirda Kahar ◽  
A.M. Zetty Akhtar ◽  
Siti Rabiatull Aisha Idris ◽  
Mahadzir Ishak
Keyword(s):  
Cooling Rate ◽  
Electroless Nickel ◽  
Optical Microscope ◽  
Air Cooling ◽  
Image Analyzer ◽  
Cooling Rates ◽  
Optical Microscope Image ◽  
Finish Material ◽  
The One ◽  
Relationship Of

This paper presents a study on relationship of cooling rates towards the intermetallic compound (IMC) morphology. Cooling rate is an important parameter as it has significant effect towards the IMC microstructure formation that indirectly affects solders joint reliability. However, there is still insufficient study regarding the effect of cooling rate on the IMC thickness and microstructure behavior by using Nickel Boron as surface finish material in the electronic packaging industry. In this study, Sn-3Ag-0.5Cu solder was used on Nickel Boron as coating layer. Cooling rates were obtained by cooling specimens in different media which is water and air. The elemental composition was confirmed using Energy-dispersive X-ray spectroscopy and the microstructure of each IMC then analyzed using optical microscope, image analyzer and ImageJ. In this study, faster cooling rate (water) found to provide thicker IMC (6μm) compared to the other medium used. The morphology shape of each IMC also differs between different medium of cooling. IMC that undergoes faster cooling showed continues like layer while the one using air cooling formed scallop like IMC.

Effect of Cooling Rate on Morphology and Crystallography of Lath Martensite in Fe-Ni Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 1459-1463 ◽  
Author(s):  
Shigekazu Morito ◽  
Ryota Igarashi ◽  
Keiichiro Kamiya ◽  
Takuya Ohba ◽  
Tadashi Maki
Keyword(s):  
Cooling Rate ◽  
Lath Martensite ◽  
Ni Alloys ◽  
Ni Alloy ◽  
Diffraction Patterns ◽  
Quenching Method ◽  
Austenite Grain Boundary ◽  
Relationship Of ◽  
Step Quenching ◽  
Martensite Structure

The development of blocks and subblocks in the lath martensite was observed with SEM/EBSD and TEM/Kikuchi diffraction patterns analyses. Morphology of lath martensite formed below Ms temperature was observed using step quenching method in 18 mass% Ni maraging steel. The development of lath martensite structure can be described as follow; lath groups with single K-S variant start to form at the austenite grain boundary. Next, other sub-blocks appear adjacent to the lath groups formed first and these lath groups form macroscopic blocks observed in optical microscopy. The morphologies of the lath martensite in Fe -23 mass% Ni alloy cooled at different cooling rates after austenitization were also observed. The packet size and block thickness decreases with increasing cooling rate, although the sub-block thickness do not change. A packet locally contains small packets with different relationship of close packed planes, and the amount of small packets increases with increasing the cooling rate.

Study on Relationship of Abnormal Heat Treatment, Microstructure and Properties of P91 Steel

2011 ◽  
Vol 311-313 ◽  
pp. 830-834
Author(s):  
Xue Xia Xu ◽  
Jie Ouyang ◽  
Xiao Guang Niu ◽  
Yan Ting Feng ◽  
Wen Peng Li
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Gradual Transition ◽  
Dual Phase ◽  
Tempered Martensite ◽  
Phase Zone ◽  
P91 Steel ◽  
Microstructure And Properties ◽  
Relationship Of ◽  
Reduced Temperature

Improper heat treatment may result in unsatisfactory microstructure and mechanical properties for P91 steel. In this work, the effect of abnormal heat treatment on microstructure and properties of P91 steel were studied. Results showed that with the normalization temperature increased from 860°C to 1000°C, the microstructures of P91 steel are ferrite, mixture of ferrite and martensite, and tempered martensite correspondingly. Cooling rate after austenization has important influence on microstructure and properties. The tempered microstructure has a gradual transition from coarse inhomogeneous ferrite to finer martensite when the cooling rate increased from 1 to 3°C/min. The reduced temperature normalization has no significant effect on hardness even as low as 860°C under aircooling condition, whereas the hareness is inadequate when the cooling rate is too slow. Incomplete austenization and transformation in dual phase zone may account for the phenomenon.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Effects of cooling rate on the mechanical properties of dual phase treated vanadium steels

1983 ◽  
Vol 41 ◽  
pp. 220-221
Author(s):  
L.J. Chen ◽  
H.C. Cheng ◽  
J.R. Gong ◽  
J.G. Yang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Automobile Industry ◽  
High Strength ◽  
Weight Percent ◽  
Low Alloy Steels ◽  
Dual Phase ◽  
Resource Requirement ◽  
Alloy Steels ◽  
Potential Weight

For fuel savings as well as energy and resource requirement, high strength low alloy steels (HSLA) are of particular interest to automobile industry because of the potential weight reduction which can be achieved by using thinner section of these steels to carry the same load and thus to improve the fuel mileage. Dual phase treatment has been utilized to obtain superior strength and ductility combinations compared to the HSLA of identical composition. Recently, cooling rate following heat treatment was found to be important to the tensile properties of the dual phase steels. In this paper, we report the results of the investigation of cooling rate on the microstructures and mechanical properties of several vanadium HSLA steels.The steels with composition (in weight percent) listed below were supplied by China Steel Corporation: 1. low V steel (0.11C, 0.65Si, 1.63Mn, 0.015P, 0.008S, 0.084Aℓ, 0.004V), 2. 0.059V steel (0.13C, 0.62S1, 1.59Mn, 0.012P, 0.008S, 0.065Aℓ, 0.059V), 3. 0.10V steel (0.11C, 0.58Si, 1.58Mn, 0.017P, 0.008S, 0.068Aℓ, 0.10V).

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

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