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09
2021
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02
Foundry: What problems usually occur with ductile iron?
Foundry
Foundry: Ductile iron is a high-strength cast iron material developed in the 1950s, with comprehensive properties close to those of steel. Based on its excellent performance, it has been successfully used to cast some parts with complex stress and high requirements for strength, toughness, and wear resistance. It has rapidly developed into a widely used cast iron material, second only to gray cast iron. The so-called 'iron replacing steel' mainly refers to ductile iron.
Foundry: Ductile iron It is a high-strength cast iron material developed in the 1950s, and its comprehensive performance is close to that of steel. It is based on its excellent performance that it has been successfully used to cast some parts with complex stress, high strength, toughness, and wear resistance requirements. It has rapidly developed into a widely used cast iron material second only to gray cast iron. The so-called "iron instead of steel" mainly refers to ductile iron.
Ductile iron obtains spherical graphite through spheroidization and inoculation treatment, which effectively improves the mechanical properties of cast iron, especially the plasticity and toughness, thereby obtaining higher strength than carbon steel.
The following two problems usually occur:
1. Shrinkage cavity and porosity
Due to the pasty solidification characteristics of ductile iron, the cast iron produced often has defects such as shrinkage cavities and porosity due to poor feeding. In order to predict these defects before casting production, numerical simulation of the casting process has been carried out at home and abroad as early as the Indian era.
Numerical simulation of the casting process is the use of numerical simulation technology to simulate the actual casting formation process in a computer virtual environment, including the filling process of metal liquid, the cooling and solidification process, the stress formation process, judging the influence degree of the main elements in the forming process, and predicting the structure, performance and possible defects, to provide a basis for optimizing the process and reducing waste products.
2. Blowhole defect
In the production process of ductile iron castings, some smooth-walled holes with a diameter of about 0.5-3mm and a spherical, oval or pinhole shape are often found during heat treatment, shot blasting or machining. These holes are generally distributed 2-3mm under the skin of the casting, which is the so-called subcutaneous porosity.
Foundry : The formation of subcutaneous porosity is due to the large surface tension of the magnesium-containing iron liquid, which easily forms an oxide film, which has a certain impact on hindering the discharge of precipitated gas and invading gas. These gases remain under the skin and form pores. In addition, the pasty solidification characteristics of ductile iron cause the gas channels to be blocked earlier, which will also promote the formation of subcutaneous porosity defects.
Ductile iron, foundry
Shandong Gongchen Machinery Technology Co., Ltd.
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Address: Mucun Town, Fangzi District, Weifang City, Shandong Province
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