The purpose of this study was to determine the impact of niobium addition as an inoculation element on the microstructure and electrochemical properties of EN-FGL250 gray cast iron. Niobium additions are in a powder f...The purpose of this study was to determine the impact of niobium addition as an inoculation element on the microstructure and electrochemical properties of EN-FGL250 gray cast iron. Niobium additions are in a powder form and have a 0.5 mm particle size at dfferent proportions of 1 wt.% and 3 wt.%. The addition was done during casting of the metal in the mold at the last cooling step of the melt cast iron. These additions have a significant impact on the phenomenon of solidifi cation as the metal powder deposited in the sand molds creates new centers of germination and absorbs a lot of heat. The cooling rate directly affects the microstructure and electrochemical behavior. This is confirmed by SEM observations and electrochemical tests. Furthermore, the addition of niobium transforms the microstructure of gray cast iron from cellular structure into totally dendritic structure. As a consequence, the niobium addition affected the shape and size of graphite, thus considerably reducing the corrosion current density by increasing the polarization resistance Rp.展开更多
Vermicular cast iron is used in certain fields because of its special physical properties. However, it is difficult to control the quality from the front of the furnace owing to the narrow range of vermiculizer and ot...Vermicular cast iron is used in certain fields because of its special physical properties. However, it is difficult to control the quality from the front of the furnace owing to the narrow range of vermiculizer and other elements that can be added to the iron. A real time method was developed to monitor the vermicular- graphite ratio of the cast iron based on fast measurements of the melt surface tension. The system includes a detector and a control unit that measure the amplitude and frequency of bubbles rising in the melt. This paper describes the methodology for measuring the surface tension of the melt and test results monitoring the vermicular-graphite ratio of the vermicular cast iron from the front of the furnace. The relationship between surface tension and graphite shape has been established. The results show that this system can quickly evaluate the vermicular-graphite ratio of the cast iron.展开更多
文摘The purpose of this study was to determine the impact of niobium addition as an inoculation element on the microstructure and electrochemical properties of EN-FGL250 gray cast iron. Niobium additions are in a powder form and have a 0.5 mm particle size at dfferent proportions of 1 wt.% and 3 wt.%. The addition was done during casting of the metal in the mold at the last cooling step of the melt cast iron. These additions have a significant impact on the phenomenon of solidifi cation as the metal powder deposited in the sand molds creates new centers of germination and absorbs a lot of heat. The cooling rate directly affects the microstructure and electrochemical behavior. This is confirmed by SEM observations and electrochemical tests. Furthermore, the addition of niobium transforms the microstructure of gray cast iron from cellular structure into totally dendritic structure. As a consequence, the niobium addition affected the shape and size of graphite, thus considerably reducing the corrosion current density by increasing the polarization resistance Rp.
基金the National Natural Science Foundation of China (No. 50174023) the Heilongjiang Province Key Task Project of Science and Technology (No. G00A12011)
文摘Vermicular cast iron is used in certain fields because of its special physical properties. However, it is difficult to control the quality from the front of the furnace owing to the narrow range of vermiculizer and other elements that can be added to the iron. A real time method was developed to monitor the vermicular- graphite ratio of the cast iron based on fast measurements of the melt surface tension. The system includes a detector and a control unit that measure the amplitude and frequency of bubbles rising in the melt. This paper describes the methodology for measuring the surface tension of the melt and test results monitoring the vermicular-graphite ratio of the vermicular cast iron from the front of the furnace. The relationship between surface tension and graphite shape has been established. The results show that this system can quickly evaluate the vermicular-graphite ratio of the cast iron.
