某材料为16MND5的压力容器筒体,在进行低温-20 ℃冲击试验时,取样位置邻近试样的冲击功却相差很大。通过对冲击功不同的试样分别进行金相检验、断口分析、化学成分分析以及能谱微区成分分析,找出了冲击功相差较大的原因。结果表明: 冲击功较低试样中的钼和硅等元素微观聚集程度比冲击功较高试样中的严重,尤其是钼元素的微观聚集更为严重; 由于合金元素钼和硅在钢中能提高钢的韧脆转变温度,因此偏聚严重就会导致材料在低温冲击时的冲击功相差较大; 由此可以判定是由于热处理工艺不当,造成了钼和硅等合金元素的严重微观聚集,致使材料出现冲击韧度不均匀、相邻位置冲击功相差较大的问题。

Large difference of impact absorbing energy existed among specimens sampling from adjacent positions of a pressure vessel cylinder with material of 16MND5, when impacted at -20 ℃. The reason for the large difference of impact absorbing energy was found out by metallographic examination, fracture analysis, chemical compositions analysis and EDS micro-area compositions analysis. The results show that micro aggregation level of Mo, Si and other elements of specimens with lower impact absorbing energy was more serious than those of specimens with higher impact absorbing energy, especially for Mo element, which resulted in the large difference of impact absorbing energy because Mo and Si could raise the ductile-brittle transition temperature of the steel. So it could be concluded that it was because improper heat treatment process that resulted in the serious micro aggregation of Mo and Si elements and non-uniform of impact absorbing energy.