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Concept of solidification of casting metals

- A molten metal in which high energy state. As the melt cools, it loses energy to form crystals

- Since heat loss walls near the model faster than anywhere else, the first crystallites form submicroscopic metal called nuclei here.

- Melt experience difficulty starting crystallites have no impurity crystallization nuclei to start.

- However in such conditions and form crystals melt undercools so nucleus or seed.

- Nuclei formed as above tends to grow at the second stage of solidification.

- The crystal growth proceeds with energy released by melting crystal interface. Crystal growth occurs on dendritic manner.

- Dendritic growth takes place at the evolution of small arms on the original branches of individual dendrites.

- Gives the resulting solid dendrites grain.
(a) a Slow cooling the dendrites grow long while rapid cooling causes short dendrite growth.
(b) Since the end be dendrites grain, slow cooling results in large grain structure and rapid cooling in small grains in the metal structure solidified.

- As solidification proceeds, growing more and more weapons on existing dendrite and also dendrites more and more the form until all crystallized melt.

- Dendrite Growth weapons because metal atoms attach themselves to solid dendrite.

- Smashing arrange themselves into three-dimensional pattern is repeated many times during the crystal growth.

- The unit of repetition is called unit cells. Unit cells arrange themselves in straight lines.

- Just so lines in a geometric pattern formed right angles to each other to produce dendritic structure.

- Dendrite growth that out until they contact the dendrite nearby and generate grain boundaries, ie boundaries between crystals or grains

- Quiet probably the army dendrite concentrated and ultimately can solid crystal or grain stay no expression on dendritic growth.

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Sand Casting of Metals

sand casting is often used in the industry (automotive, aerospace, etc.) to make parts that are composed of iron, bronze, brass and aluminum times. The metal is melted in a furnace of choice and poured into a mold cavity made of sand. Sand casting is used because it is cheap and the process is relatively simple. However, that common flaws in sand cast parts and can the flaws of the properties of materials cast. As a result, it can this be used to teach both the sand casting process and also to demonstrate that the effect on the formation of fault processing.

This module builds on previous models and experiments located on the website coupled listed under recommended prerequisites. If the necessary equipment and furnaces readily available, see the Materials Processing modules and / or Processing Effects on Structures and Properties for a potential replacement.

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Interfacial Heat Transfer Coefficient of Casting Metals

Interfacial heat transfer coefficient of casting metals has a great influence on the casting solidification process. Especially in the process of casting metals, casting interface often comes into being gaps which are the control factors of heat transfer for solidification process. At the same time, the interfacial heat transfer coefficient is one of the essential boundary conditions for computer solidification simulation. The accuracy will directly affect the reliability of numerical simulation. In the actual casting metals solidification process, the interfacial heat transfer coefficient changes with the temperature and the different process conditions. Thus the exact solution is relatively difficult.

Interface heat transfer coefficient of casting metals solidification is not a constant. It is the function which changes over time. It will decrease to a stable value with the increase of solidification time. In the process of actual simulation, most of the simulation softwares set the interfacial heat transfer coefficient to a constant value, which creates a larger deviation between the simulation results and the actual results. To get accurate interfacial heat transfer coefficient has important application value and referential meaning for the casting metals simulation process.

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