The project of defects and microstructure control of large alloy ingot and forging done by Shenyang National Laboratory for Materials Science (SYNL) researchers has recently been granted the second prize of National S&T progress award. Carried out by Prof. LI Dianzhong, Prof. LI Yiyi and other researchers at SYNL, this project belongs to the field of materials and metallurgy, involving the multidisciplinary systems of steels, metallurgy, thermal forming, and computer simulation for major engineering.

The manufacturing capacity of large castings and forgings is an important symbol to measure the industrial level of a country. However, many large castings and forgings in China, such as the water turbine wheels in the Three Gorges Project (TGP) and nuclear power pressure vessels, had been dependent on import and controlled by foreign countries for a long time, which seriously restricted the progress of major projects and threatened the economic and national security.

SYNL and the key enterprises tackle problems with joint efforts, closely focusing on the development demand of China's major industry such as energy and electricity, metallurgical machinery, shipbuilding, etc., extracting scientific problems from production practice and developing a set of key technologies. The defects and microstructure control problems of large alloy ingot and forging have been solved, and major innovative achievements are as follow:

1) The mechanism of type A segregation in large ingot was found, and the theory of defect formation in macrosegregation and the technique of ingot preparation with low segregation were developed.

2) The controlling mechanism of key phases in a series of materials was clarified, and the problem of strength and toughness matching was solved, guaranteeing the quality stability of key components in energy engineering.

3) A multi-scale and whole-process computation and simulation system was established to accurately predict the forming, defect, and microstructure evolution in many large castings and forgings, shortening the development period and significantly improving the qualified rate of products and material utilization.

The project has been granted 22 invention patents, and the overall technology has reached the international leading level. It realizes the localization of the key parts in major projects and gets rid of the passive situation that the large castings and forgings are controlled by foreign countries. Moreover, it improves the overall manufacturing technology level of China’s large casting and forging and provides a successful example for the cooperation between research institutes and large enterprise groups.