Development of casting solidification technology

The growth of solidification technology of investment casting

1. The coagulation, craft of the so-called passed workmanship, the country is to make the liquid metal heat along the necessarily to exclude, or through a process of liquid metal to implement a target purpose of rapid solidification, which makes the development of the grain (solidification) to stop toward the inevitable target, with both sides, after all, to the grain structure or single crystal structure of the casting technology of a kind of way.Because an inexhaustible improve cooling craft and restraint, that heat out the strength and the underlying purpose of endless progress, so that the sight of solid-liquid boundary along the gradient of temperature in the liquid phase increases, this not only makes the grain the underlying purpose of the development of progress, and to construct more tall and straight, and delayed the directional area. Passed craft solidification has been widely used in gas turbine blade forging high temperature alloy yield, because along the development of the directional structure mechanics function is good, to make leaf slice things temperature greatly progress, making progress aviation policy motivation function.The latest stop in sequential solidification is the production of single crystal castings, such as single crystal turbine blades, which have higher temperature, thermal resistance, creep resistance and erosion resistance than ordinary sequential solidification columnar blades.The adoption of this kind of superalloy single-crystal blade aero-engine has significantly improved the thrust and efficiency of aero-engine.

2. Rapid solidification technology means that the liquid alloy is changed into solid state under the premise of cooling rate (10-4-10k /S) much faster than that of the usual process (103-109 K/S).It makes the alloy material with excellent structure and function, such as very fine grain (usually < 0.1-0.01um > or even nanometer size grain), alloy element segregation defects and high separation degree of ultrafine precipitated phase, material high strength, high toughness and so on.The rapid solidification technique allows liquid metals to deform the crystallization process (nucleation and development) that indirectly forms the amorphous arrangement of solid materials, known as metallic glass.This kind of amorphous alloy has a long distance disordered layout and has special electrical, magnetic, electrochemical and mechanical functions.Such as used as control transformer core material, computer head and core equipment parts of the material, fiber welding materials.Rapid solidification is being faced up by many people.

3. Another development of the composite material preparation and solidification technique is the preparation of composite materials. The so-called composite materials are materials with special functions that cause the reinforcing phase or special components in the nonmetallic or metallic matrix to disperse or arrange the reinforcing phase according to the desired pattern through controlled solidification.Because the matrix of composite material with high fragmentation, coupled with the existence of the strengthening phase, therefore, can be expressed and popular single phase structure function material of differences, such as high strength, excellent high temperature function and anti falters, function, and has grown the way of preparing a variety of composite material technology, such as connecting passed solidifying craft preparation of authigenic composite material.The use of this area will have a broader vision.

4.Semi-solid forging semi-solid metal forging technology after more than 20 years of research and growth, has entered the stage of industrial use.Its reason is in the process of liquid metal solidification stop intense agitation (can take machine, electromagnetic or other style), the popular casting to form the branch crystal collection skeleton was destroyed, constitute the separation of granular structure shape, thus made of semi-solid metal, it has a certain activity, then the money can be manipulated forming craft of fruit such as die casting, extrusion, forging forming blank or casting.Semi-solid metal forging forming subdued the traditional forging forming of shrinkage, shrinkage, porosity and wrong size error, error, low forming temperature, delay the die life, save energy, improve yield premise and condition, progress casting quality (cut hole and solidification shorter), a lot of advantages such as cutting machining allowance.Semi-solid metal forming process will become one of the most promising near - net forming and forming technologies in the 21st century.