钢中珠光体球团尺寸的EBSD表征技术

借助光学显微镜和扫描电镜等研究了珠光体球团的表征方法,从阻止裂纹扩展的有效性出发,选择内部取向接近、外部取向差较大的球团簇作为评价珠光体球团尺寸的指标。结果表明,珠光体中铁素体的取向分布与球团吻合,即铁素体的大角度晶界就是球团(簇)界,所以可以通过表征铁素体的晶粒尺寸来评价珠光体球团尺寸。该方法的关键点在于晶界如何定义和样品如何制备。从对EBSD法的可行性分析可知,以15°作为晶内最大取向差来划分珠光体球团。对于珠光体钢,电解抛光法更适用于珠光体中渗碳体片层较宽的样品,而对于珠光体中渗碳体片层过窄的情况更适合选用离子抛光法。 

EBSD characterization method of pearlite nodule size in steel

The method of characterization of pearlite nodule was studied and discussed by means of EBSD,optical metallography and scanning electron microscopy( SEM). From the view of preventing the crack propagation,the nodules with similar internal orientation and large external orientation difference were selected as an indicator of pearlite nodule size evaluation. The results show that the orientation distribution of ferrite in pearlite coincides with that of the nodule,that is,the large angle grain boundary of ferrite coincides with the nodule boundary,so the pearlite nodule size can be evaluated by characterizing the grain size of ferrite. The key point of this method is how to define the grain boundary and how to prepare the sample. From the feasibility analysis of the EBSD method,it is known that the pearlite nodules are divided by 15° as the maximum orientation difference. For pearlitic steel,the electropolishing method is more suitable for a sample with a wider cementite layer in the pearlite,and the ion polishing method is more suitable for the case where the cementite layer in the pearlite is too narrow.