【作者】 邱宇； 庞建超； 杨恩娜； 李守新； 张哲峰；

【Author】 Qiu Yu;Pang Jianchao;Yang Enna;Li Shouxin;Zhang Zhefeng;Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences;

【机构】 中国科学院金属研究所沈阳材料科学国家(联合)实验室；

【摘要】 蠕墨铸铁兼具良好的导热性和优异的力学性能,在现代发动机缸盖行业中起着举足轻重的作用。本文主要研究了蠕墨铸铁(RuT300)的抗拉强度随温度的变化规律,并利用原位扫描电镜技术对其随温度变化的拉伸断裂行为与开裂机制进行了系统研究。实验结果表明:蠕墨铸铁的抗拉强度随温度的升高不断下降,其变化趋势主要分为两个阶段:第Ⅰ阶段为随温度的升高缓慢下降,第Ⅱ阶段为随温度升高快速下降。其中RuT300的原位拉伸扫描观察结果可以很好的解释上述变化趋势:裂纹在蠕虫状石墨处萌生后,在第Ⅰ阶段由于晶内滑移在铁素体晶内进行扩展;在第Ⅱ阶段由于晶界转动裂纹沿着铁素体晶界进行扩展。这些新的发现可能对铸铁材料的优化设计提供新的线索或理念。更多还原

【Abstract】 Compacted graphite iron(CGI) plays more and more important role in the industry of diesel cylinder because of its good thermal mechanical properties.In this study,transition of tensile strength and corresponding damage mechanisms observed by in-situ technique at room and elevated temperatures have been investigated.The results show that tensile strength of CGI decreases with increasing the tensile temperature,and this trend can be divided into two stages:the decreasing rate is slow in the first stage,and fast in the other stage.This can be explained very well by the observations on the morphology evolution of CGI:after initiation from vermicular graphite,micro-crack propagates into ferrite grains due to the slip bands in the first stage,and does along the grain boundaries due to the grain rotation.The newly proposed mechanism can provide a new clue for the optimum design of cast iron.更多还原