製程參數對低碳當量沃斯回火球墨鑄鐵機械性質的影響

Effects of Processing Variables on the Mechanical Properties of Low Carbon Equivalent Austempered Ductile Irons

涂人福(Tu Jen Fu)

指導教授 ： 施登士 ； 張晉昌

國立臺灣師範大學/科技學院/工業教育學系/碩士(1999年)

摘要

摘要
本實驗設計低碳當量（CE4.0、CE3.7）之球墨鑄鐵經360℃、390℃沃斯回火處理後加以分析比較，其中碳當量4.0之材料分別有加入Ni及未加Ni，利用影像分析系統分析石墨參數，X-ray繞射測定沃斯田鐵的殘留量，再配合SEM觀察沃斯回火球墨鑄鐵的顯微組織。
實驗結果顯示，添加Ni對於材料之球化率、球墨數以及機械性質無明顯影響。在較低溫360℃沃斯回火，回火時間對其伸長率的影響不如390℃時來得明顯。於高溫390℃沃斯回火，回火時間對伸長率影響較大。在相同的球墨數及熱處理條件下，球墨平均直徑愈小者，伸長率的表現相對較佳。
抗拉強度隨著球化率增加而略有提昇；球化率較高者伸長率較佳。球墨數增加，伸長率也有增加的趨勢。球墨面積分率的增加，抗拉強度降低，伸長率隨著球墨面積分率的增加而減少。石墨尺寸較大抗拉強度較低，伸長率也較低。
實驗結果顯示低碳當量沃斯回火球墨鑄鐵之機械性質，可達到ASTM A-897-90 標準之熱處理條件有：（一）550℃預熱15分鐘，900℃沃斯田鐵化90分鐘，再於360℃沃斯回火120分鐘後，空冷至室溫，可達到ASTM A-897-90 1200/850/4等級標準。（二）550℃預熱15分鐘，900℃沃斯田鐵化90分鐘，再於390℃沃斯回火60分鐘後，空冷至室溫，可達到ASTM A-897-90 1050/700/7等級標準。
關鍵詞：製程參數、低碳當量、石墨、沃斯回火球墨鑄鐵。

關鍵字

製程參數 ； 石墨 ； 低碳當量 ； 沃斯回火球墨鑄鐵

並列摘要

ABSTRACT
The mechanical properties of two different carbon equivalent （4.0、3.7）ductile cast irons after austempered treatment in 360℃ and 390℃ were investigated. Added Ni in the CE4.0 ductile cast irons were compared with no Ni ones. Used image analysis system to analysis graphite parameter. X-ray diffraction was used to evaluate retain austenite fraction. SEM was applied for micro-graph observation of etched specimens of ADIs.
Experimental results showed that Ni additions had not remarkable effect on nodularity, nodule count and mechanical properties. Effect of elongation by austempered time in 390℃ was more remarkable than in 360℃. Under same nodule count and treatment, the tested elongations increased by the nodular graphite diameter decreased.
Ultra tensile strength （UTS） was associated with nodularity increased, but UTS increased little. Increasing nodule count, the tested elongations had a increased trend. Increasing graphite area fraction reduced both UTS and tested elongations. Increasing the diameter of nodular graphite decreased tested elongations.
The mechanical properties of this study applied for ASTM A-897-90 standard, the heat treatment processes had two methods：（1）specimens were preheated at 550℃ for 15 min and asutenitized at 900℃ for 90 min, after which they were quenched in a salt bath at 360℃ for 120 min. After the austempered treatment, specimens were then air-cooled to room temperature. After this method the mechanical properties can reach ASTM A-897-90 1200/850/4 grade standard.（2）specimens were preheated at 550℃ for 15 min and asutenitized at 900℃ for 90 min, after which they were quenched in a salt bath at 360℃ for 60 min. After the austempered treatment, specimens were then air-cooled to room temperature. After this method the mechanical properties can reach ASTM A-897-90 1050/700/7 grade standard.
Keyword：processing variables , low carbon equivalent, graphite, ADI.

並列關鍵字

processing variables ； graphite ； low cabon equivalent ； ADI

參考文獻

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