Cold drawn steel surface crack
Cold-drawn steel is commonly used machine materials. Common cold drawn steel, cold drawn round bar, cold drawn flat steel, cold drawn hexagonal rods, etc., the material is usually stainless steel, carbon steel, free cutting steel, bearing steel. The cold-drawn steel processing, with the size of high precision, bright surface characteristics. In actual production, this advantage is only for hot-rolled material, compared with other bright materials, such as skinning or polishing materials, cold-drawn steel because the surface cracks appear more likely to be at a disadvantage. Cold-drawn steel crack is usually very superficial, throwing 20 to 50 can be eliminated, is a minor crack.
From the billet production process point of view, the generation of steel cracks, and the following three factors are closely related.
① Steel inclusions. Rolling, inclusions in the molten steel, and the oxygen content is higher, resulting in oxides, in the manufacturing process and can not be thoroughly cleaned, resulting in cracks.
② Surface fold. The steel is folded during the rolling so that the surface of the steel presents cracks that are linear or jagged along the rolling direction.
③ Subcutaneous bubbles. Some subcutaneous bubbles near the surface, heating, when the billet surface oxidation or burning, the subcutaneous bubbles will be exposed, oxidized, can not be welded, resulting in cracks.