视力检查表

中国机械工程学会无损检测学会 GB9445-2008（ISO9712-2005）要求 视力检查 4 If the pressure on steel ingot is not enough at the direction during the process of cogging or rolling, it is easy to form a concave groove and it might become surface crack along the material fiber in the lather forging or rolling. 4.5 Secretions the length of these cracks may equal to the length of the rolled products such as rod, late, strip and tube. This kind of cracks is usually visible. 5 Since burrs or foreign matters may exist on the roller, the material may have a slight cut, and becomes fine surface crack during the lather rolling. 6 These fine cracks may have a long length. When the steel being rolled is at high temperature, heavy oxide scales formed. 7 If the scales are rolled into the steel, surface cracks could be also formed. These cracks may lie in longitudinal, transverse or in irregular directions. 8 Seams are not one, existed on or near the surface of the steel, but also in the interior or even in the center of the body. Sometimes the number of seams in internal hole of machining parts is more than seams on the surface. 注：申请报考无损检测人员资格等级证书者应符合GB9445-2008标准（ISO9712-2005）要求的视力：无论是否经过矫正，在不小于30cm距离处，一只眼睛或两只眼睛的近视力应能读出Times New Roman 4.5或等同大小的字母（Times New Roman 4.5点的垂直高度，每1点为1/72in或0.3528 mm） [中国机械工程学会无损检测学会编制•执行标准：GB/T9445-2008（等同于ISO9712-2005标准）] 文件编号: SLJC-01 版本号: 200905-01 发布日期: 2009-5-8