Wire can also be called wire rod. When using wire, the surface of the wire will be linearly cracked, and there will be straight or curved thin lines along the rolling direction. This is the so-called wire crack, which is a longitudinal crack. The wire also has transverse cracks, which are discontinuous. The reasons for these cracks are:
The causes of  wire cracks are:
(1) Defects such as longitudinal or transverse cracks, scars, subcutaneous bubbles or non-metallic inclusions on the billet have not been eliminated. After rolling, they are exposed to form longitudinal cracks. Steel ingots with high sulfur and phosphorus content are relatively deformed during rolling. In severe cases, it is easy to cause vertical or horizontal cracks;
(2) The heating is uneven, and the extension and width of each part of the rolled product are different;
(3) Improper heating process of high carbon steel wire rod blanks (preheating speed is too fast, heating temperature is too high) or the cooling speed of the rolling stock is too fast to generate excessive thermal stress to form cracks, the latter may also appear lateral cracks;
(4) If the pinholes on the continuous casting billet are not cleaned, they will be extended, oxidized, and welded after rolling to cause linear hair lines in the finished product;
(5) Improper controlled cooling process after rolling, the cracks formed are not accompanied by decarburization, and there is generally no scale in the crevices.
The ways to eliminate wire cracks are:
(1) Strictly check the quality of the blank, and the unqualified blank will not be put into production;
(2) Strengthen the heating operation of the blank, control the heating speed, heating temperature and uniform heating;
(3) Formulate a reasonable rolling system to keep the temperature of each part of the rolled piece uniform;
(4) Control the cooling process after rolling.