Cause and Control of Poor Fusion of High N-Cr Centrifugal Compound Rolls of 480×900

Author of the article:YANG Zhiqiang1 , LYU Weiwei1 , SU Chen1 , GUO Hongxing2

Author's Workplace：1. School Electrical, Kunming Industrial Vocational and Technical College, Anning 650302, China; 2. Yunnan KISC Heavy Equipment Manufacturing Group Co., Ltd., Anning 650302, China

Key Words：poor fusion layer; centrifugal composite casting; high nickel-chromium roll

Abstract：The bad fusion between the working layer and the core was the most important casting defect in 准480×900 high Ni-Cr infinite cold ductile iron rolls. This defect was usually difficult to repair and directly leads to scrap of the rolls. The analysis of the defects of the high Ni-Cr infinite chilled cast iron roll of the 480 ×900 centrifugal composite casting has found that the main causes of bad fusion were low centrifugal pouring stop temperature and slow static pouring core filling speed in the working layer. When pouring molten iron in the working layer, excessive addition of ‘O’ type glass slag, too low casting temperature of molten iron in the core and poor purity of molten iron would also cause bad fusion defects. According to the above reasons, the prevention and control measures were put forward: according to the product size and process design measures, reasonable adding ‘O’ type glass slag; Centrifuge shutdown should be selected in the working layer of metal crystallization platform temperature below 10~20 ℃ ; The molten iron in the core was poured by top injection method and the temperature was controlled in the range of 1 385~1 410 ℃. The results show that reducing the time interval between centrifuge shutdown and molten iron pouring at the core can effectively prevent the bad fusion between the working layer and the core