Introduction and Discussion of a Quantitative Evaluation Method for Banded Structure in Steel

Referring to the American standard ASTM E1268-2001(2006), a quantitative evaluation method for banded structure in steel was developed. The establishment of grid measurement line, the influence of magnification factor and the number of field of view on measurement results, and the corresponding relationship between quantitative evaluation method and national standard rating results were analyzed. The results show that when creating grid measuring lines, the accuracy by automatic creation was higher than that by manual creation. The accuracy of quantitative rating of field of view maps collected at low magnification (50-200×) met the requirements. The acquisition of five field of view could basically meet the needs of statistics and calculation. When the relative accuracy value was higher than 30%, the number of field of view could be increased to improve the accuracy of measurement results. In quantitative evaluation method, the values of orientation degree and anisotropy index increased with the increase of banded structure grade. However, there was no clear correspondence between the values of orientation degree and anisotropy index and banded structure grade in atlas comparison method in national standard.