Research On The Composition Segregation Of Cu-15Ni-8Sn Alloy In Permanent Mold And Sand Mold Casting Ingots

The Cu-15Ni-8Sn alloy is a high strength wear resistant copper alloy and can be applied to withstand greater stress and friction conditions,commonly used for the production of bearings or bushings for large machinery and equipment.However,the alloy is prone to produce serious macro-segregation of tin during the casting process.In addition,defects such as porosities and shrinkages easily occur,which lead to the sharp decline of the ingots' performance,also affect the subsequent thermal processing and heat treatment process results.In this paper,aiming at the Cu-15Ni-8Sn alloy ingot's casting problems,by using spectrometer,metallurgical microscopy,electron microscopy,researched on the composition macro-segregation of Cu-15Ni-8Sn alloy,and the other casting defects were also analyzed.Finally the casting process parameters were optimized.The main results of the dissertation are as follows:(1)Researched on the macro-segregation characteristics of Cu-15Ni-8Sn alloy ingots by permanent mold and sand mold casting,found that the macro-segregation in the horizontal direction of the alloy ingot was serious and the macroscopic segregation in the vertical direction was slight,macro-segregation of the ingot cross-section of the middle of the Sn content is low,both sides of the high Sn content,showing the phenomenon of invers-segregation.The absolute value of the radial macro-segregation at the bottom part of the permanent casting ingot was 0.3wt.%,the sand type was 1.05 wt.%,in the center part of the permanent casting ingot was 2.23 wt.%,the sand type was 3.10 wt.%,in the upper part of the permanent casting ingot was 1.91 wt.%,the sand type was 1.13 wt.%.The Sn element of macro-segregation of permanent casting ingot is less severe than sand casting ingot.(2)Researched on the effects of pouring temperature and mold temperature on macro-segregation in Cu-15Ni-8Sn alloy.It is found that with the decrease of pouring temperature,the macro-segregation of Sn element is effectively inhibited.The optimum pouring temperature of the permanent mold casting was 1261? and that of the sand ingot was 1269?.When the mold temperature is 200?,Different parts of the Sn elemental composition of macro-segregation less.(3)Researched on the other cast defects of permanent mold cast Cu-15Ni-8Sn alloy ingot.It is found that the pouring temperature increases and the porosity increases.The temperature of mold increases,and the porosity decreases.The pouring temperature and mold temperature affect the defects of ingot porosity and macro-segregation.Based on the permanent mold,the combination of pouring temperature of 1250? and mold temperature of 250?,and increased riser height,which could effectively decrease the macro-segregation,porosity and shrinkage of Cu-15Ni-8Sn ingot.The experimental results are as follows the factory is applied.