Aluminum alloy casting mechanical performance prediction method

Abstract

The invention provides an aluminium alloy casting mechanical performance prediction method, comprising: first casting a sample, establishing a relationship among a mechanical performance, porosity and secondary dendrite arm spacing; then constructing a mathematical model of microscopic porosity and secondary dendrite formed in a casting solidification process; and finally predicting values of the microscopic porosity and the secondary dendrite by a computer before casting, and predicting a mechanical performance of an aluminum alloy casting according to the relationship among a mechanical performance, porosity and secondary dendrite arm spacing. When the predicted mechanical performance is not up to standard, an improved casting technique enables the mechanical performance to meet design requirements, so as to achieve a purpose of nondestructive testing. The invention has the advantages that the casting technique is optimized, casting quality is ensured, once casting is achieved, and an important application value is achieved.

Description

technical field [0001] The invention relates to the technical field of mechanical numerical simulation, in particular to a method for predicting the mechanical properties of aluminum alloy castings. Background technique [0002] With the development of aluminum alloy casting technology and the characteristics of light weight, high specific strength, good corrosion resistance and low production cost, aluminum alloy castings provide a wide range of application fields, and aluminum alloys are gradually becoming large, complex, With the development in the direction of high strength, the requirements for the mechanical properties and internal quality of aluminum alloy castings are also getting higher and higher. The mechanical properties are often tested by pouring samples in the same furnace. The internal quality inspection is divided into non-destructive inspection and body destructive inspection. For large castings, in addition to the body destructive inspection when necessary...

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Problems solved by technology

Non-destructive inspection mainly uses radiographic flaw detection, ultrasonic flaw detection, magnetic particle flaw detection, etc. These methods can only detect the mechanical properties and internal quality of the casting after solidification, but cannot predict the performance and structure of the casting before pouring

[0003] The mechanical properties of castings are the main indicators of casting acceptance. Many castings are scrapped because their mechanical properties do not meet the requirements. For example, a certain type of military product is an important weapon and equipment for Chinese naval ships. It is up to 3800*2300*2650mm, with a net weight of 2700kg, and the cost of raw materials alone is as high as 240,000 yuan per piece. The structure is very complicated, but its mechanical properties and internal quality requirements are very high. The crystallization range of ZL114B aluminum alloy is relatively wide, and it is easy to produce microporous defects during the solidification process, which affects its internal quality and reduces the mechanical properties. Therefore, it is very necessary to predict the mechanical properties of the castings before pouring, understand the solidification status of the castings, and predict the defects of the castings. Make the mechanical properties meet the requirements of use by changing the process parameters and other means

Under the production conditions where the chemical composition and casting process are very stable, the as-cast mechanical properties of the casting are related to the porosity of the casting (the ratio of the actual density to the theoretical density when there are microscopic pores) and the secondary dendrite spacing. The porosity and secondary dendrite spacing of alloy castings have been studied. It is generally believed that the micropores are formed by the interaction of hydrogen and solidification shrinkage; the secondary dendrite spacing is mainly caused by the supercooling when equiaxed crystals are formed. Depending on the degree, the content of the research involves the initial conditions when the micropores are formed, the size, shape and distribution of the pores, the metallographic parameters, the influence of the grain size on the performance, etc., most of which are still in the basic research stage. There are no examples of predicting the mechanical properties of actual castings, especially for the ZL114B aluminum alloy with a wide liquid-solid two-phase region

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