Cracks of smls pipe are:

First, the tube (round steel) for many reasons, the internal contains more cracks, inclusions, air bags and so on. Organization of the uneven is the reasons for the tube, pay attention to the choice of the implementation of the tube blank standard, a certain size of the manufacturers of round bar on the line.

Second, the perforation of the temperature, process adjustment can not be ignored, if the perforation temperature is low, improper adjustment, will also cause the organization within the capillary tear.

Third, the finished annealing temperature is appropriate. Perforation heating temperature 1180 ~ 1230 ℃, low, which is the temperature of carbon steel, take 1230-1250 was appropriate. Furnace time is generally more than 60min.