縮墨鑄鐵製程穩定性之研究

Abstract

本研究針對三種球化劑(KC合金、CG合金、稀土元素)在生產縮狀石墨鑄鐵時，所需添加量及在儘可能同一製程參數下了解金相組織和機械性質的穩定性，並探討以兩種不同退火處理的冷卻速度下所得基地組織之穩定性等情形作一研究。 實驗結果指出以CG合金球化劑生產縮墨鑄鐵所需添加含量為0.8%，KC合金球化劑生產縮墨鑄鐵所需添加含量為0.3%，稀土元素生產縮墨鑄鐵所需添加含量為0.45%，以上三種球化劑皆需添加0.2%的接種劑。經統計KC合金之縮墨率變異數為44.98標準差為6.71其值最小，且八個爐次縮墨率平均值為83.13%，所以添加KC合金所生產之縮墨鑄鐵縮墨率最高，製程最穩定。另外基地組織則以CG合金變異數17.41標準差4.17，值最小，穩定性最高。 由實驗結果得知以CG合金所生產之縮墨鑄鐵所獲得的機械性質普遍都較佳，穩定性也較高。縮墨鑄鐵在進行退火處理時，最後階段不管是爐冷至260℃再移至空冷或者直接進行空冷都不影響獲得完全肥粒鐵組織。

This paper is mainly focusing on the study of the amount of the three kinds of spheroidizing, KC alloys、CG alloys、Rare earths that is needed to produce the compacted graphite cast iron, and on the study of the stability in the process of producing optical microscope observation and mechanical property under as identical condition as possible. Besides, this paper will do the comparison between the stability of the two base structures under two different speed of annealing. The results shows that the amount needed to produce the compacted graphite cast iron is 0.8% with CG alloy-spheroidizing, 0.3% with KC alloy-spheroidizing, 0.45% with Rare earths; and what’s more, the above three kinds of spheroidizing have to add 0.2% dose of inoculation. According to the gauging, the coefficient of variance of the KC alloys compacted rate of graphite is 44.98, and the standard deviation of it is 6.71, which is the smallest. In addition, the average figure of the eight-time experiment is 88.13% so to add KC alloys can produce.the highest the compacted rate of graphite of producing the compacted graphite cast iron, and have most stable processof producing it. moreover,the base structure that the coefficient of variance of CG alloys is 17.41,and the standard deviation of it is 4.17,which is the smallest, and have most stable. From the results of the experiment, CG alloys can produce better mechanical property of the compacted graphite cast iron, and have more stable process of producing it. When the compacted graphite cast iron is under the process of the annealing, neither the temperature quenching down to 260°C in the stove before quenching in the air nor quenching the temperature directly in the air will have influence on getting the complete ferrite structure.