What defects can be caused by the interaction of liquid metal with the mold

What are the factors that affect the quality of castings formed by liquid metal+?

Hello dear, what factors affect the quality of liquid metal forming castings + sound? Aluminum castings are leather metal objects obtained by casting methods, that is, the smelted liquid metal is smelted, injected into the pre-prepared casting mold by pouring, injection, inhalation or other methods, and after cooling, it is sandlessed, cleaned (see casting cleaning) and post-treatment (see casting post-treatment), and the object with a certain shape, size and performance is obtained. Let's take a look at the liquid forming casting process The liquid forming casting process can be so widely used because it has the following advantages:

1) It can manufacture blanks with complex internal cavities and shapes. (2) The process is flexible and adaptable. The size of the liquid molded parts is almost unlimited, and all metal materials that can be dissolved into a liquid state in the industry can be used for liquid molding, and for cast iron with poor plasticity, liquid molding is the only way to produce its blanks or parts.

3) The cost of liquid molded parts is low. Liquid molding can directly use waste parts and chips, and the equipment cost is low; At the same time, the machining allowance of liquid molded parts is small, saving metal. There are many factors that affect the quality of castings, the first is the design manufacturability of castings; second, there must be a reasonable casting process; the third is the quality of raw materials used for casting; The fourth is process operation, to formulate reasonable process operation procedures, improve the technical level of workers, so that the process regulations can be correctly implemented.

However, there are many processes for liquid metal molding, and it is difficult to accurately control them, which makes the quality of castings unstable. Compared with forgings of the same material, due to the loose structure and coarse grains of liquid molding, it is easy to produce internal defects such as shrinkage porosity, shrinkage porosity, and porosity. Its mechanical properties are low.

Casting stress refers to three types: thermal stress, phase transformation stress and shrinkage stress. The causes of various stresses vary. Thermal stressThermal stress is caused by uneven thickness of the section at the intersection of different geometric shapes of the casting, and inconsistent cooling.

Compressive stresses are formed at the thin walls, resulting in residual stresses in the casting. Phase change stressThe phase change stress is due to the phase transformation of some cast aluminum alloys during the cooling process after solidification, which brings about a change in volume and size. It is mainly caused by the uneven wall thickness of aluminum castings and the phase transformation of different parts at different times.

Shrinkage stress: When the aluminum casting shrinks, it is hindered by the mold and core and produces tensile stress. This stress is temporary, and the aluminum casting will disappear automatically out of the box. However, improper unpacking time will often cause thermal cracks, especially the aluminum alloy cast in the metal type is often prone to thermal cracks under this stress.

The residual stress in the cast aluminum alloy parts reduces the mechanical properties of the alloy and affects the machining accuracy of the cast aluminum alloy parts. Residual stresses in aluminum castings can be eliminated by annealing. Multi-element analyzer and carbon and sulfur analyzer test the composition of chemical elements and control the material.

Due to the good thermal conductivity of the alloy, there is no phase change during the cooling process, as long as the design of the dust and lack structure of the casting is reasonable, the residual stress of the aluminum casting is generally small.

What measures can be taken to address the non-breathability of metal molds when casting metal molds?

Kiss! Hello, happy to answer your <>

The metallophilic type itself is not breathable, and certain measures must be taken to remove the air in the cavity and the gas generated by the sand core. 1. It is suitable for making blanks with complex shapes, especially with complex inner cavities; 2. Wide adaptability and low cost; 3. For some materials with poor plasticity, such as cast iron, sand casting is the only forming process for manufacturing its parts or blanks. Applications:

Engine cylinder block, cylinder head, crankshaft and other castings of automobiles (2) investment casting investment casting: It usually refers to the casting scheme in which the model is made of fusible materials, and several layers of refractory materials are coated on the surface of the pattern to make the shell, and then the pattern is melted and discharged out of the shell, so as to obtain a casting mold without parting surface, and the casting scheme can be filled with sand and poured after high temperature roasting. It is often referred to as "lost wax casting".

I hope mine can help you! Do you have any other questions?

Summary. The difference between cast alloy and as-cast alloy is that aluminum alloy can change the concentration of alloy by slag removal, low density, but relatively high strength, close to or more than high-quality steel, good plasticity, can be processed into various profiles, has excellent electrical conductivity, thermal conductivity and corrosion resistance, is widely used in industry, and the amount of use is second only to steel. Aluminum alloys are divided into two categories:

Cast aluminium alloy, used in the as-cast state; Deformed aluminum alloy, can withstand pressure processing, mechanical properties are higher than cast. It can be processed into aluminum alloy of various shapes and specifications. It is mainly used in the manufacture of aviation equipment, daily necessities, doors and windows for construction, etc.

What are the differences in the properties of the same metal in cast and pressure working state?

The difference between cast alloy and cast state tells this alloy hello, aluminum alloy can change the concentration of alloy by slag removal, low density, but relatively high strength, close to or more than high-quality steel, good plasticity, can be processed into various profiles, with excellent electrical conductivity, thermal conductivity and corrosion resistance, widely used in industry, the amount of use is second only to steel. Aluminum alloys are divided into two categories: cast aluminum alloys, which are used in casting and permeability; Deformed aluminum alloy, the spine can withstand pressure processing, and the mechanical properties are higher than those in the as-cast state.

Can you add, I don't quite understand it.

The difference between cast alloy and cast state tells this alloy hello, aluminum alloy can change the concentration of alloy by slag removal, low density, but relatively high strength, close to or more than high-quality steel, good plasticity, can be processed into various profiles, with excellent electrical conductivity, thermal conductivity and corrosion resistance, widely used in industry, the amount of use is second only to steel. Aluminum alloys are divided into two categories: cast aluminum alloys, which are used in casting and permeability; Deformed aluminum alloy, the spine can withstand pressure processing, and the mechanical properties are higher than those in the as-cast state.

After hot forging, the deformation of the internal structure of the ingot can be summarized as follows:

1) Coarse columnar grains are plastically deformed and recrystallized into new equiaxed fine-grained structures.

2) Defects such as looseness, voids, and micro-cracks are compacted and welded under three-way compressive stress.

3) The oxides with high melting point are broken and distributed in the form of broken grains or chains along the direction of metal deformation, and the intergranular impurities with low melting point (such as sulfides) are distributed in bands along the direction of deformation.

On the other hand, what does it have to do with refillability?

1. The gating system, the gating system includes a straight sprue, a cross sprue, an inner sprue and a riser, which is a channel for the forming of metal liquids, and the gating system is poor, and the filling capacity is poor.

2. The temperature of the metal liquid, the appropriate pouring temperature is very important for filling.

3. Casting mold and casting surface coating. The paint is good, and the filling capacity is also strengthened.

In addition, the purity of the metal liquid, the speed of pouring, the temperature of the mold, etc., all have an impact.

the role of force - impact and erosion, etc.; It may cause sand holes, cracks, deformation and oversize of castings.

Poor and other defects. the action of heat – caused by heat exchange; It may lead to defects such as sand inclusion on the surface of the casting or shrinkage of the surface of the casting.

Chemical processes – combustion of organic matter, carbon powder may lead to further oxidation of porosity in castings, slag inclusion defects and core macros.

the role of force - impact and erosion, etc.; It may cause sand holes, crack bypassing, deformation and size of castings.

Poor and other defects. Early code action of heat – caused by heat exchange; It may lead to defects such as sand inclusion or surface subsidence on the surface of the casting.

Chemical processes – combustion of organics, carbon powder can lead to porosity in the casting, slag inclusion defects and further oxidation of the casting surface.