Simulation Investigation Of Inclusions Distribution In Die Steel H13 Ingot Manufactured By High Pressure Metallurgy

Mold is an extremely important and special basic process equipment in industrial production.With its excellent comprehensive performance,the second-generation hot die steel H13 has become the most widely used mold steel in China and the world.However,domestic hot die steel H13 has many problems such as low purity,more inclusions and low service life.So this paper takes steel H13 as the research object.By measuring the temperature variation curve of ingot and mold during process of pressure solidification,the Beck nonlinear estimation method is used to investigate the heat transfer between the ingot and the mold.Based on the macroscopic transmission principle,combined with the change of physical property parameters with pressure,the inclusions distribution model of pressure solidification has been established.Using the model after verification,the effect of technological parameters such as solidification pressure,size and type of inclusions on distribution has been revealed,which promotes the development of domestic technology on high quality hot die steel H13 to some extent.The main research contents and conclusions of this topic are as follows:(1)During the process of smelting hot die steel H13 under the solidification pressure of 0.1 MPa,1MPa and 2 MPa by 25kg pressure induction furnace,the temperature of ingot and mold has been measured,and the interface heat transfer coefficient under different pressures has been obtained by Beck nonlinear estimation method.Comparing the temperature curve and the interface heat transfer coefficient under different pressures,increasing pressure can obviously enhance the interface heat transfer conditions between the ingot and the mold.(2)Based on the macroscopic transmission principle,combined with the Euler-Eulerian model,interface heat transfer coefficient and property parameters of H13 steel under different pressures,the inclusions distribution model of pressure solidification has been established,which is compared with the measurement of inclusion distribution and literature report.The model has good credibility and accuracy.It can be used to explore the influence mechanism of process parameters on the distribution of inclusions during pressure solidification.(3)The effects of process parameters such as solidification pressure、pouring temperature and the diameter and type of inclusions on the distribution of inclusions have been analyzed.The results show that the drag force plays a leading role in the driving force of inclusion movement,followed by the resultant force of gravity and buoyancy.The additional mass force is much smaller than other forces.As the diameter of the inclusion increases,the number of floating inclusions increase.With the increase of solidification pressure,the number of inclusions remains the same at the edge of the ingot.The concentration at the center of the ingot is obvious and the upward floating tendency is increased.Increasing the pouring temperature,the inclusions float obviously and gather gradually at the edge.Compared with Al2O3 inclusions,SiO2 inclusions float more easily and have a higher probability of aggregation on the side...