Abstract：Hairline cracks of edge in pipeline steel was one of the common surface defects. The cause and control methods of hairline cracks of pipeline steel were studied by series of experiments. The result showed that the hairline cracks of pipeline steel was caused by the cracking at the feeble locations on the sides of casting billet during the rolling process. And the plate deformation of upper and lower surface was inhomogeneous during the rolling process. The extension of lower surface was less than the upper surface. Thus, leading to the hairline cracks of lower surface were further away from the plate edge than the upper surface, and the hairline cracks of lower surface could not be removed normally. Improving the uniformity of casting billet heating could alleviate the uneven rolling deformation, but could not completely solve the problem of hairline cracks of lower surface of pipeline steel. In the end, the extension of the lower surface was increased while the rolling speed of lower roller was greater than the upper roller during the process of widening stage of roughing mill. The hairline cracks of the upper surface was 15 mm away from the plate edge and that of the lower surface was 25 mm. The hairline cracks of upper and lower surface could be normally cut. The production efficiency and output proportion of pipeline steel was increased.
2018, Vol. 28 
