固溶強化元素矽及鎳對肥粒體基球墨鑄鐵熱循環誘發沿晶脆性破壞之影響

Effect of Solid Solution Strengthening Element Silicon and Nickel on Thermal Cycling Induced Intergranular Embrittlment of Ferritic Spheroidal Graphite Cast Iron

陳科憲(K. H. Chen) ； 林宏茂(H. M. Lin) ； 呂傳盛(T. S. Lui)

《鑄造工程學刊》 46卷4期 (2020/12) Pp. 1-12

摘要

本研究擬藉由在低矽含量（～2.1wt％）的球墨鑄鐵中，分別添加固定含量（～2.0wt％）的固溶強化元素矽及鎳，用以分別探討矽元素與鎳元素對球墨鑄鐵中的含鎂介在物聚集於共晶包界區域程度之影響，以及這兩種元素所造成的含鎂介在物聚集程度對肥粒體基球墨鑄鐵熱循環誘發沿晶脆性破壞之效應。實驗結果顯示由於矽與鎳元素的添加將造成介在物在共晶包界區域的聚集程度增加，球墨鑄鐵的室溫延伸率傾向於隨著矽及鎳元素添加而降低，且其400℃的延伸率及熱循環後的延性劣化率亦隨著矽及鎳元素添加而增加。此外，由熱循環後拉伸破斷面形貌觀察可知，低矽含量（～2.1wt％）試片在150次熱循環後其破面形貌仍然為靨渦狀的延性破壞，而添加矽及鎳的試片均隨著熱循環次數的增加，由靨渦狀或劈裂狀的破面形貌轉為沿晶破面形貌。

關鍵字

肥粒體基球墨鑄鐵 ； 固溶強化元素 ； 熱循環誘發脆性破壞

並列摘要

This study intends to add fixed contents (~2.0wt%) of solid solution strengthening elements silicon and nickel to spheroidal graphite cast iron with low silicon content (~2.1wt%) to explore the effect of silicon and nickel on spheroidal graphite cast iron, that the influence of the degree of aggregation of magnesium-containing inclusions in the cast iron in the eutectic cell boundary regions, and the effect of the degree of clustering of magnesium-containing inclusions caused by these two elements on the thermal cycle of ferritic spheroidal graphite cast iron induced intergranular embrittlement. The experimental results show that the addition of silicon and nickel will increase the degree of clustering of the inclusions in the eutectic cell boundary regions. The room temperature elongation of spheroidal graphite cast iron tends to decrease with the addition of silicon and nickel, and its extension at 400℃ The deterioration rate of elongation after thermal cycling also increases with the addition of silicon and nickel. In addition, according the observation of the tensile fracture surface morphology after thermal cycling, the fracture surface morphology of the low silicon content (~2.1wt%) specimen after 150 thermal cycles is still dimple ductile fracture, but the silicon or nickel addition specimens with the increase of the number of thermal cycles, the fracture morphology of the dimple fracture morphology or cleavage fracture morphology changed to the morphology of the intergranular embrittlment fracture surface.

並列關鍵字

Ferritic spheroidal graphite cast iron ； Solid solution strengthening element embrittlment ； Thermal cycling induced intergranular fracture