针对各汽车企业标准都要求汽车用薄钢板表面粗糙度Ra<2 μm的客观条件, 对多种不同类型表面形貌特征的样板采用不同的取样长度(以0.8 mm和2.5 mm为主)和取样区间数进行了表面粗糙度测量对比试验, 以检验欧洲标准DIN EN 10049-2006将汽车用薄钢板表面粗糙度测量的取样长度由ISO 4288:1996中的0.8 mm更改为2.5 mm是否科学合理。结果表明: 采用0.8 mm和2.5 mm取样长度测得不同薄板的表面粗糙度变化情况不同, 两者各有大小, 因样板的表面结构特征而异, 与“取样长度增大, 测量的Ra值也应相应增大”这一传统观点并不相符; 从促进世界贸易角度出发, 在汽车用薄钢板Ra测量中坚持遵循ISO 4288:1996选用0.8 mm的取样长度有利于数据溯源。

In view of the objective condition that all car enterprise standards require the automotive steel sheet surface roughness Ra<2 μm, surface roughness contrast test was done to many specimens with different surface morphology characteristics by using different sampling length (mainly 0.8 mm and 2.5 mm) and sampling interval numbers, in order to test whether it is reasonable that DIN EN 10049-2006 changed sampling length from 0.8 mm of ISO 4288:1996 to 2.5 mm for automotive steel sheet surface roughness measurement. The results show that the changing trend of surface roughness by using 0.8 mm and 2.5 mm sampling length was different for different sheets, and it was decided by the surface morphology characteristics of the sheet specimens, which was not consistent with the traditional view that the measured Ra value increased with the increase of sampling length. So from the view of promoting world trade, obeying ISO 4288:1996 and selecting 0.8 mm sampling length for automotive steel sheet Ra measurement are favorable for data tracing.