高矽肥粒體基球墨鑄鐵熱循環誘發沿晶破壞之最高加熱溫度效應探討

A Study on the Effect of Maximum Heating Temperature on the Cyclic-Heating-Induced Intergranular Fracture of High-Silicon Ferritic Spheroidal Graphite Cast Iron

林宏茂(H.M. Lin) ； 呂傳盛(T.S Lui) ； 陳立輝(L.H. Chen)

《鑛冶：中國鑛冶工程學會會刊》 50卷3期 (2006/09) Pp. 92-103+91

https://doi.org/10.30069/MM.200609_50(3).0010

摘要

本研究主要探討肥粒體基球墨鑄鐵熱循環誘發沿晶脆性破壞之最高加熱溫度效應。實驗結果顯示肥粒體基球墨鑄鐵於最高加熱溫度750℃，其熱循環後拉伸性質發生明顯的劣化。而於最高加熱溫度升高至800℃時，肥粒體晶粒有明顯的再結晶現象發生，而此現象可抑制脆性破壞產生。此外，試片於最高加熱溫度850℃時，熱循環後試片可觀察出基地有部分相變態情形。試片於750℃熱循環一定次數後，試片之拉伸斷面可辨識出一定面積率之沿晶破壞。熱循環誘發的初始裂紋位置為肥粒體基地上之最後凝固的共晶包界區域，這些區域通常有含鎂氧化介在物存在。

關鍵字

球墨鑄鐵 ； 熱循環 ； 脆性破壞 ； 介在物

並列摘要

In this study, the effect of maximum temperature on cyclic-heating -induced embrittlement of ferritic spheroidal graphite cast iron was examined. Experimental results indicated that significant deterioration of tensile properties appeared when the maximum heating temperature was 750°C. Significant recrystallization of ferrite grains occurred when the heating temperature was raised to over 800°C and this suppressed the embrittlement. Moreover, evidence of partial phase transformation was observed when the maximum heating temperature was raised to 850°C. When a specimen was heated to 750°C with a certain number of cycles, a distinct area fraction of intergranular fracture could be recognized from tensile fractography. The initiation site of these thermal cracks was at the prior-solidificational eutectic cell boundary of the ferrite matrix, which is related to magnesium-containing oxide inclusions.

並列關鍵字

Spheroidal graphite cast iron ； Cyclic heating ； Embrittlement ； inclusions