【摘要】 本文研究了稀土镁球墨铸铁球化后铁水氧活度与球化率之间的关系,确定了判定稀土镁球墨铸铁球化率的氧活度界限。应用氧浓差电池法检测稀土镁球铁球化率,简便易行,可快速准确地用于球铁生产的炉前检测。更多还原

【Abstract】 Analyzing thermodynamically the relation among the dissolved elements,oxygen actitvity and residuals of RE and Mg,a conclusion is reasoned out for the RE-Mg treated ductile iron that the graphite morphology has a closed connection with the oxygen activity.Based on this analysis,a method for rapidly determining the oxygen activity by using an oxygen probe containing mainly a concentration cell to measure the cell cmf and thermo-emf has been successfully introduced to appraise the effect of spheroidization of RE-Mg on the ductile iron.Both the experiment,as presented in this paper,and practice under production conditions give the following results.1.The method,in virtue of that the oxygen activity of molten iron determined as above is representative of the important factors influencing spheroidization,is reasonable and reliable.2.Time history exhibits that a significant change of oxygen activity occurs due to spheroidization.The oxygen activity and sulphur content in molten iron increase while RE and Mg residuals decrease because of the fading effect on spheroidization.3.For the RE-Mg treated ductile iron,a critical value of oxygen activity is defined properly as 1.8 ppm,below which a better effect of spheroidization will be convincibly obtained and the cast iron can then be classified as the first and second classes in quality.On account of the fading effect,the critical value of oxygen activity should be lowered to 1.0 ppm in production.4.The method,by virtue of its simplicity and rapidity,is easy to use in production.Only 10~20 seconds are necessary to obtain the steady emf curves after inserting the oxygen probe into molten iron,and then to quickly calculate the oxygen activity or more easily to find it out from the table prior calculated.更多还原