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AISI 1045 steel has the characteristics of high strain rate, large strain, and sharp rise in temperature during high-speed deformation process, resulting in a concentrated deformation band and fine structure. In this work, the microstructure of submicron-sized grains in AISI 1045 steel material formed under 10 6 s –1 during a high speed cutting process was examined. To reveal the dynamic evolution mechanism of the AISI 1045 microstructure, the continuous dynamic recrystallization theory was introduced. The results show a high dislocation density which favor the formation of small angle grain boundaries during the high speed cutting process. Kinetics calculations that use continuous dynamic recrystallization mechanisms prove that the recrystallization size is constant when the strain rate ncreases from 10 3 s –1 to 10 6 s –1, and the transition time is reduced from 6×10 –5 s to 4×10 –8 s. The recrystallization grains were gradually formed during the deformation of the material, not generated after the deformation.

Through the fatigue test of modified spur gear with root crack fault by fatigue testing machine，the rule of root crack propagation is obtained，the root crack is easier to expand along the direction of tooth width than the direction of tooth root， and the growth rate is slow at first and then fast. The automatic propagation of the root crack of modified spur gear with same initial crack is analyzed by using the simulation software FRANC3D， and the propagation direction and path of the crack are determined. By comparison， the simulation results are consistent with the experimental results， which shows that the constructed simulation model is verified by the fatigue test， and the reliability of the conclusion is proved. The research on the propagation path and direction of root crack can provide a reliable basis for the design and manufacture of practical gears. On the basis of this study， the related problems of crack growth life are discussed.

This paper introduces the development status of moderate-scale management of grain and oil in Nanchang, analyzes the existing problems in production and management, puts forward some suggestions in terms of fund, science and technology and industrial structure, and lists some cases for reference, so as to provide a direction for the operation of grain and oil in Nanchang. [ABSTRACT FROM AUTHOR]

Nanchong City is a major grain production city in Sichuan Province. The annual use of agricultural plastic film for grain and oil crop production and the amount of waste agricultural plastic film produced are very large. How to properly recycle agricultural plastic film and reduce the non-point source pollution of agricultural plastic film to agricultural environment has become an unavoidable subject of agricultural production in Nanchong City. In recent years, the scientific recycling of agricultural plastic film in Nanchong City has made great achievement. On the basis of statistical survey, this paper elaborated the main methods and results achieved, analyzed the existing problems, and came up with recommendations for the future work, in the hope of providing a reference for strengthening agricultural plastic film recycling in similar situations. [ABSTRACT FROM AUTHOR]