Jian Yun Li

Developed New Type of Pneumatic Spray Nozzle and Research of Spray Characteristic

The Pneumatic atomizing nozzle is quenching test professional nozzle which is designed for new quenching process taking high-pressure nitrogen gas water as quenching medium. It meets the requirements of high pressure nitrogen quenching process and reaches the requirements that particle size can be adjusted, flow spray field coverage angle is large, flow and pressure are adjustable and the amplitude of accommodation is big. The nozzle special for high-pressure gas quenching test is less and it can only be chose from other functional nozzles, having great limitations. The development of nozzle special for high-pressure gas quenching will have a certain role in promoting the popularization of high-pressure gas quenching technology and the development of nozzle technology.

Numerical Simulation of Pressure Difference about Curve Ball in Flight

Life lies in movement, Football is now the most popular sport in the world. Fluent12.1 software is employed in this thesis to model the numerical simulation of the pressure which the ball with different angular velocity and different velocity bears. Simulation results show that the pressure difference on the surface of the ball with a certain speed will increase if the angular velocity increases. The pressure difference on the surface of the ball with a certain angular velocity will increase if the velocity increases. The radian of ball will become more bigger.

Stress Field Numerical Calculation for T10 Steel Quenched by Atmosphere-Pressure High-Velocity Nitrogen-Water Spray Based on DEFORM

In this paper, by using the result calculated with FORTRAN program based on nonlinear estimation method, the stress field of T10 steel specimen quenching process is solved and analyzed. In order to get an in-depth understanding of the stress field in the specimen, the accurate calculation model and appropriate simplification must be considered. Because T10 steels phase is non-uniform when quenching, in order to get the accurate result, the heat release of phase changing must be considerate.

Comparison of Surface Heat-Transfer Coefficient of GCr15 Steel Quenched by Clear Water and Nitrogen-Spray Water

In order to simulate the thermal stresses, thermal strains and residual stresses of steel during quenching by numerical means, it is necessary to obtain an accurate boundary condition of temperature field. The explicit finite difference method, nonlinear estimate method and the experimental relation between temperature and time during water and nitrogen-spray water quenching have been used to solve the inverse problem of heat conduction. The relations between surface heat-transfer coefficient in water and nitrogen-spray water quenching and surface temperature of cylinder have been given. In numerical calculation, the thermal physical properties of material were treated as the function of temperature. The results show that the relations between surface heat-transfer coefficient and surface temperature are non-linear during water and nitrogen-spray water quenching, the heat-transfer coefficient is bigger when water quenching than when nitrogen-spray water before 580°C, the heat-transfer coefficient is smaller when water quenching than when nitrogen-spray water after 400°C. The results of calculation coincided with the results of experiment. This method can effectively determine the surface heat-transfer coefficient during water and nitrogen-spray water quenching.

Experimental Study on Nitrogen-Spray Water Quenching for 9SiCr

Alloy steel 9SiCr is quenched by a certain proportion of mixture gas of nitrogen and spray water at atmosphere, and the continual cooling curve during quenching is determined, the rigidity of quenched workpiece is measured and the metallographic map is captured. The results show that it can improve the cooling effect of quenching medium on the one hand; on the other hand, it can decrease the deformation and residual stress of workpieces. The results show that the rigidity of quenched workpiece is about 62 (HRC), which is corresponding with the rigidity after oil quenching. Martensite phase transformation occurs at the end of quenching that can be seen from the metallographic map.

Study on Cooling Performance of Eject Quenching by Mixture of Nitrogen-Spray Water

Though gas quenching has several advantages, such as minimal environmental impact, little deformation, low energy cost, clean products, and ability to control the cooling locally and temporally for best product properties, its cooling performance is less than that of oil and water. If gas is mixed with spray water, the mixture will has favorable cooling performance. The cooling performance of eject quenching by mixture of Nitrogen-spray water is studied experimentally. Alloy steel 9SiCr is specimen, and it is quenched by a certain proportion of mixture gas of Nitrogen and spray water under normal pressure and high velocity, and the continual cooling curve is determined. The experimental results show that it can improve the cooling effect of quenching medium on the one hand; on the other hand, it can decrease the deformation and residual stress of specimen. The results also show that cooling performance of the mixture and cooling velocity can be enhanced by increasing gas pressure when the mixture ratio is fixed, and it takes short time to cool to room temperature. The cooling performance of the mixture and cooling velocity can be enhanced by increasing the mixture ratio under same pressure, and it also takes short time to cool to the room temperature. The continual cooling curve is determined, which gives the information of cooling performance of eject quenching by mixture of Nitrogen-spray water under Normal pressure changed with the pressure and the mixture ratio of Nitrogen and spray water.

The Effect of the Structure of Collection Loop on Two-Phase Flow Field in Quenching Furnace

In order to analyses the effect of structure of collection loop on two-phase flow field in quenching furnace, the complex flow field in furnace for mixture of Nitrogen and spray water ejecting quenching under normal pressure and high velocity is numerically simulated with Mixture model of two-phase flow by CFD software FLUENT. Different inlet velocity, different volume percent of spray water, different velocity differences between Nitrogen and spray water, and different angle and dimension of collection loop affected on outlet velocity are analyzed. The research results show that the flow field is really complex, and around inner and outside canister and collection loop back flow exists. The angle of collection loop has less effect on outlet velocity, and the inner diameter of collection loop has more effect on outlet velocity. The simulation results show that the furnace can accelerate the flow of quenching media, which can cool specimen quickly.

Study on Surface Heat Transfer Coefficient of Mixture of Nitrogen-Spray Water Eject Quenching under Normal Pressure and High Velocity

During mixture of Nitrogen and spray water ejecting quenching under normal pressure and high velocity, the liquid film that is formed on the surface of specimen to reduce the heat transfer between specimen and quenching media is removed on the one hand; on the other hand, the heat transfer performance of the mixture exceeds that of pure Nitrogen. Because the surface heat transfer coefficient is difficult to measure, according the cooling curve of surface and centre of specimen measured experimentally, the law of surface heat transfer coefficient and specimen temperature is calculated by nonlinear estimate methods and finite difference method based on inverse heat transfer method. The results show that the cooling performance of mixture of Nitrogen and spray water is as well as that of water or oil. During quenching, the surface heat transfer coefficient increases rapidly at begin, and at temperature of 170 °C, the surface heat transfer coefficient decreases. During martensite phase transformation, the latent heat is used to increase drive force of phase transformation and to overcome resistance of phase transformation, thus the martensite phase transformation can fulfill.

Stress Strain Analysis of Steel Specimens Not Wholly Quenched

A finite element model of not wholly quenched steel fatigue specimen is established. Hardness value of some distance to work piece surface are assumed different and cyclic strength coefficients of different zones are different, both is assumed to be proportional to hardness value. Elasto-plastic finite element analysis was carried out for this model. According to the stress-strain distribution on transverse section, the effect of not wholly quenched on fatigue crack initiation life is analyzed.