Factors affecting the surface roughness of stainless steel castings
Surface roughness is another major quality indicator for stainless steel castings, generally less than 3.2 μm, between 0.8 and 3.2 μm. There are many factors affecting the surface roughness of castings, such as the pressure type, the surface quality of the investment and stainless steel, the casting process, the type of alloy and other factors.
(1) Profile and investment surface quality. The surface roughness of the investment mold is the most important part affecting the surface roughness of the casting, and it is related to the surface quality of the molding, the compression molding method and the pressing process parameters.
(2) Stainless steel surface quality. Stainless steel is a columnar columnar structure network, and refractory materials, additives, and water are filled in the middle, so that there are pores of different sizes on the surface after dry roasting. The penetration of molten metal into the surface of the stainless steel is the main cause of the surface roughness of the part. The penetration depth of the molten metal is related to the crystal diameter, the average diameter of the surface pores, and the radius of curvature of the surface of the alloy liquid.
Therefore, in order to obtain a smooth stainless steel casting, it is necessary to reduce the diameter of the crystal and the filler particles, and reduce the surface pore diameter 庐; or to fill the larger pores with an additive that can be concentrated on the surface to reduce the penetration depth of the molten metal. .
(3) Influence of casting process. The process parameters such as the temperature of the stainless steel, the pouring temperature of the molten metal, the pressure head and the vacuum degree during casting have an influence on the surface roughness of the casting, especially the influence of the type temperature and the pouring temperature.
The relationship between the temperature of the stainless steel and the casting temperature of the molten metal and the surface roughness of the casting. As the temperature and pouring temperature of the molten metal increase, the filling property of the molten metal is improved, the depth of penetration into the pores of the surface layer is increased, and the surface roughness of the stainless steel casting is increased.
(4) The effect of the alloy. The thermal conductivity is small. After the stainless steel is used, the metal liquid pouring type is cooled slowly, and the obtained casting grains are coarse, and the intergranular grooves may roughen the surface of the casting, and the grain boundary groove depth may even reach 7 μm. To this end, the alloy should be modified, and a filler such as zircon with better thermal conductivity is used to increase the cooling rate of the stainless steel casting, so that the surface layer of the casting is finer to reduce the surface roughness of the casting.
Surface roughness is another major quality indicator for stainless steel castings, generally less than 3.2 μm, between 0.8 and 3.2 μm. There are many factors affecting the surface roughness of castings, such as the pressure type, the surface quality of the investment and stainless steel, the casting process, the type of alloy and other factors.
(1) Profile and investment surface quality. The surface roughness of the investment mold is the most important part affecting the surface roughness of the casting, and it is related to the surface quality of the molding, the compression molding method and the pressing process parameters.
(2) Stainless steel surface quality. Stainless steel is a columnar columnar structure network, and refractory materials, additives, and water are filled in the middle, so that there are pores of different sizes on the surface after dry roasting. The penetration of molten metal into the surface of the stainless steel is the main cause of the surface roughness of the part. The penetration depth of the molten metal is related to the crystal diameter, the average diameter of the surface pores, and the radius of curvature of the surface of the alloy liquid.
Therefore, in order to obtain a smooth stainless steel casting, it is necessary to reduce the diameter of the crystal and the filler particles, and reduce the surface pore diameter 庐; or to fill the larger pores with an additive that can be concentrated on the surface to reduce the penetration depth of the molten metal. .
(3) Influence of casting process. The process parameters such as the temperature of the stainless steel, the pouring temperature of the molten metal, the pressure head and the vacuum degree during casting have an influence on the surface roughness of the casting, especially the influence of the type temperature and the pouring temperature.
The relationship between the temperature of the stainless steel and the casting temperature of the molten metal and the surface roughness of the casting. As the temperature and pouring temperature of the molten metal increase, the filling property of the molten metal is improved, the depth of penetration into the pores of the surface layer is increased, and the surface roughness of the stainless steel casting is increased.
(4) The effect of the alloy. The thermal conductivity is small. After the stainless steel is used, the metal liquid pouring type is cooled slowly, and the obtained casting grains are coarse, and the intergranular grooves may roughen the surface of the casting, and the grain boundary groove depth may even reach 7 μm. To this end, the alloy should be modified, and a filler such as zircon with better thermal conductivity is used to increase the cooling rate of the stainless steel casting, so that the surface layer of the casting is finer to reduce the surface roughness of the casting.
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