High-strength low stress cast nodular cast iron with high elasticity modulus and manufacturing method thereof

Abstract

The invention discloses a high-strength low stress cast nodular cast iron with high elasticity modulus. The nodular cast iron comprises the following components by mass percent: 3.7-3.9% of C, 2.0-2.2% of Si, 4.50-4.65% of CE, 0.5-0.6% of Mn, less than or equal to 0.03% of P, less than or equal to 0.02% of S, 0.03-0.06% of Mg, 0.01-0.02% of RE, 0.5-0.7% of Cu, and 0.05-0.06% of Sn. A manufacture method of the nodular cast iron is characterized by high temperature pure iron liquid of base iron, compound alloying and accurate addition; according to the microscopic structure of the manufactured nodular cast iron, the content of pearlite is more than or equal to 95%, the nodularity is more than or equal to 90%, spherulitic graphite number in unit area is 200-380 / mm<2>, the yield strength is over 400MPa, the strength of extension is over 700MPa, the elastic modulus is more than 170GPa, the hardness HB is 190-250, the elongation is more than 3%, the casting inner stress is less than or equal to 50MPa, namely, with high carbon equivalent and high silicon-carbon ratio, the nodular cast iron has excellent performances such as high strength, high elasticity modulus and low stress, thus meeting the technical requirement of casting of machine tools.

Description

technical field [0001] The invention relates to nodular cast iron, in particular to a high-strength, high-elastic-modulus, low-stress as-cast nodular cast iron suitable for manufacturing machine tool castings, and also relates to a manufacturing method of the as-cast nodular cast iron. Background technique [0002] With the continuous improvement of parts processing accuracy requirements and the development of large-scale CNC machine tools, the demand for large-scale precision machine tools has increased rapidly. At the same time, the requirements for the quality of machine tool castings that account for 70-80% of the weight of the machine tool have also been increased. Ductile iron castings (such as Grades QT600-3, QT700-2) are increasingly used in large and heavy machine tools due to their excellent performance. However, the dimensional accuracy and retention of machine tool castings have become the bottleneck in the manufacture of high-end CNC precision machine tools in m...

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Problems solved by technology

[0003]The main problems in the original technical solution for ductile iron machine tool castings are: 1. The carbon equivalent fluctuates greatly (4.00~4.60%) and is unstable ; 2. The residual stress of the casting is high and the variation range is large (100~200MPa), which seriously leads to deformation or even cracking of the casting; 3. It is difficult to achieve high strength and high elastic modulus at the same time. Generally, the tensile strength is about 600 MPa, and the elastic modulus The lower amount is about 150GPa, and the performance index of elastic modulus is almost not controlled in the domestic casting production, and the elastic modulus is rarely measured; High-magnesium and high-rare-earth spheroidizers are used for spheroidization treatment through the flushing method or capping method. The inoculant mostly uses 75# ferrosilicon, and the inoculation treatment is carried out through inoculation in the bag and floating silicon inoculation. The nodulizer and inoculant are added The amount is large, the absorption rate is low, and the physical and chemical indicators of the obtained castings are unstable

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