| The application of the Breathable steel in the injection mold can effectively solve the problem of exhaust gas trapping of the mold,improve the forming quality of the injection molding product.The existing research reports that 304/316L stainless steel is commonly used for Breathable steel materials,although it can guarantee excellent corrosion resistance,but due to this materials insufficient strength,it’s easy to fail during the working process of the mold.Therefore,in this work,a new type of high-carbon niobium-containing material is designed to improve the strength of Breathable steel.This experiment prepares breathable steel by powder metallurgy technology,The effects of powder size,green density,sintering temperature and different quenching and tempering temperatures on the comprehensive properties of Breathable steel were investigated,respectively.The main conclusions are as follows:1.By controlling different powder particle size,green density and sintering temperature,powder metallurgy Breathable steel can be prepared with high strength,high corrosion resistance and good Breathability.The finer the particle size,the better the Breathability of the Breathable steel,but the worse the mechanical properties and corrosion resistance;As the green density and sintering temperature increase,the Breathability of the Breathable steel deteriorates,but its mechanical properties and corrosion resistance has improved.After different quenching+tempering heat treatment,the comprehensive performance of the Breathable steel can be further improved.2.The Fe-13Cr-0.5Mo-3Nb Breathable steel is evenly distributed with irregular pores,and a large number of dispersed Nb6C5 particles are formed.The exist of Nb inhibits the formation of carbides of Cr,improved the strength and corrosion resistance of the material.After heat treatment,the Nb6C5 particles precipitated in the grains are finer and more diffuse.After tempering,the M7C3 carbides are mostly dissolved in the Breathable steel.3.The optimum preparation process parameters are:the powder particle size is96-120μm,the compact density is 5.6g/cm3,and the sintering temperature is 1280°C.In this process parameters The excellent comprehensive performance Breathable steel can be prepared.the relative gas permeability coefficient is 2.5465m3/h·kpa·m2,the corrosion rate is 0.016mm/y,the Breathability is comparable to similar imported breathable steel,and the yield strength higher than 150MPa.The application of the prepared Breathable steel in the injection mold can reduce the injection defects on the surface of the product,significantly improve the molding quality of the injection molding product,and improve the densification degree of the product.4.The best quenching+tempering process parametersare:1000°C quenching+300°C tempering,the Breathable steel under optimised heat-treated process shows better corrosion resistance and wear resistance,the hardness reaches 36.7HRC,compared the performance of the non-heat treatment has greatly improved. |
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