摘要：
研究了参数设置对扫描电镜检测夹杂物的影响,讨论了放大倍数、搜索网格大小、加速电压及工作距离等参数对测量夹杂物尺寸、数量的影响.研究结果表明,放大倍数越小,搜索网格的数量越少,检测到的夹杂物平均数量越少,平均夹杂物尺寸越大;当放大倍数降低到100倍左右、搜索网格为512×512、加速电压为25 kV、工作距离为17.5 mm时,能够检测到实验钢种夹杂物的平均尺寸约4μm,最小尺寸约1μm.其次,工作距离越大,加速电压越小,检测到的夹杂物数量越多,平均夹杂物尺寸越小.这主要是因为图像的分辨率随着工作距离增加和加速电压的减小而提高,进而导致在测试过程中大量细小的夹杂和析出物被检测到;因而在检测细小的夹杂和析出时,应增大工作距离或者降低工作电压,特别是在精确检测非常细小的MnS夹杂时,应适当增加工作距离至20.5 mm或降低加速电压至15 kV以下.不同测量面积设置的实验结果表明,对于本实验材料,检测面积大于20 mm2时实验结果更可靠、更具代表性.%The effects of parameter setting on detection of inclusions by scanning electron microscope (SEM) were investigated .The influences of magnification time ,searching grid size ,accelerating voltage and working distance on measured dimension and quantity of inclusions were discussed .The results showed that the average quantity of detected inclusions decreased with the decrease of magnification time and searching grid .Meanwhile ,the average size of inclusions increased .The average size and minimum size of inclusions in experimental steel was about 4 μm and 1 μm ,respectively ,under the following conditions :the magnification time was reduced to about 100 times ,the searching grid was 512 × 512 ,the accelerating voltage was 25 kV and the working distance was 17. 5 mm .Secondly ,with the increase of working distance and the decrease of accelerating voltage ,the quantity of detected inclusions increased while the average size decreased .It was because that the resolution of images was improved with the increase of working distance and the decrease of accelerating voltage .Therefore ,many small inclusions and precipitates could be detected in test process .In other words ,for the detection of tiny inclusions and precipitates ,the working distance should be increased or the working voltage should be decreased .Particularly ,during the accurate detection of very tiny MnS inclusions ,the working distance should be increased to 20. 5 mm or the accelerating voltage was decreased to less than 15 kV .The experiments with different settings of measurement area indicated that the determination results were more reliable and representative when the detection area was higher than 20 mm2 for the proposed test material .
