The world's first high-strength and high-rigidity ductile iron cylinder block was born in Yuchai

Recently, the world's first cast QT900-2 high-strength and high-rigidity ductile iron cylinder block was successfully cast at Guangxi Yuchai Foundry Co., LTD. Judging from the surface quality of the cylinder block blank, the anatomy of the body and the performance test results of the body, it is superior to the original cylinder block, and the weight has also been reduced by 30%.

The main difficulty in the production of ductile iron cylinder blocks lies in the complex structure of components and the significant differences in wall thickness. Due to the paste-like solidification characteristic of ductile iron, it is difficult to achieve feeding through conventional feeding processes. The cylinder block is extremely prone to a large number of shrinkage cavities and porosity problems, which are hard to be completely solved by conventional processes.

Based on the successful batch production of 3mm high-strength thin-walled flywheel housings replacing aluminum by using the iron mold sand-covering process, Yuchai Casting has this time adopted the as-cast QT900-2 material process to adjust and optimize many process parameters such as the original cylinder block pouring system, the thickness of the sand-covering layer and the iron mold thickness in areas prone to shrinkage porosity, and melting, achieving a complete success. At present, this process material has been applied in shaft and shell casting products such as flywheel housings, crankshafts, bearing covers, and robot reducers, achieving good results.

At present, the materials for commercial diesel engine cylinder blocks are developing towards vermicular iron. However, vermicular iron has characteristics such as low yield strength, significant performance differences with different vermiculation rates, and the need for structural strength to ensure stress generation, which makes it very difficult to achieve lightweighting with vermicular iron.

This type of high-strength and high-rigidity ductile iron has a yield strength 114% higher than that of RUT400 and an elastic modulus 13% higher, making it a new material for the lightweighting of cylinder blocks. According to estimates, if it is applied to the heaviest cylinder block of the engine, it is expected to reduce the weight by 100 kilograms. At the same time, it will make the engine upgrade and cylinder expansion extremely easy, and can eliminate the cylinder block cracking problem caused by knocking in gas engines and hydrogen-fueled engines. After being applied to Yuchai engines with a displacement of 11 liters or more, it will be able to better help customers realize commercial value It has great economic and social benefits.