Device and method for testing hot crack of aluminum alloy under condition of active applied load

Abstract

The invention relates to a device for testing hot crack of an aluminum alloy under the condition of an active applied load. The device mainly comprises a test sample mold unit, a connecting screw, a data testing unit, a frame-type connecting mechanism and a load application unit which are sequentially connected and positioned on the upper part of an equipment pedestal; and a data acquisition unit is connected with the data testing unit. Through the device for testing the hot crack of the aluminum alloy, information such as critical load and temperature change when a test sample is cracked can be acquired, and data information is provided for constructing a relation between the solid phase rate of the aluminum alloy and the applied load; and test samples with different dendritic crystal growth directions can be acquired by constructing different cooling velocities of the aluminum alloy through different heat preservation materials, and a relation between the growth direction of dendritic crystal and the hot crack is sought. The testing device is simple in structure, reasonable in design and easy and convenient to operate, is applied to easy-cracking alloy and non-cracking alloy, further enriches the category of testing equipment used in the hot crack research process, and promotes research and development of the hot crack.

Description

technical field [0001] The invention relates to an experimental device and method for testing hot cracking of an aluminum alloy under the condition of actively applying a load. The device can measure parameters such as critical load and temperature when the aluminum alloy is hot cracked, and belongs to the field of experimental research on metal materials and casting. Background technique [0002] In casting production, hot cracking is a common casting defect in castings, especially large castings, which has brought huge losses to industrial production. The occurrence of such casting defects is mainly related to the stress caused by the solid shrinkage of liquid alloy in the later stage of solidification. related to generation and development. Hot cracking of castings is a crack formed by castings at high temperature, and often occurs at the end of liquid alloy solidification, that is, in the solidus above the solidus line of the alloy. The occurrence of thermal cracks in c...

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Problems solved by technology

At the beginning of the 20th century, foundry workers began to study the formation mechanism of thermal cracks, and proposed several different theories such as strength theory, liquid film theory, comprehensive theory, and intergranular bridging theory to explain the formation of thermal cracks; With the continuous development of the casting field, the numerical simulation technology of the temperature field and the flow field in the casting process has been fully developed, and the numerical simulation research of the stress field in the casting process has also been developed, which also indirectly promotes the numerical simulation of hot cracks in the casting process. Some research results have been achieved, and some theoretical models and criteria for hot crack prediction (such as Rappaz's RDG criterion) have been proposed, but there is still no general theoretical model or criterion that can predict hot cracks more accurately.

Some information and data during the formation of liquid alloy hot cracks can be obtained by using these devices, but the hot crack test equipment used in the current experiment process is basically designed using the principle of solidification and shrinkage of the liquid alloy itself. Research on hot cracking of easy-cracking alloys, but these devices cannot meet the requirements for studying the hot cracking phenomenon of alloys with a small hot cracking tendency

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