Cold drawn seamless tubing raw materials with different chemical compositions have different fracture characteristics. The fracture characteristics can be investigated with the naked eye, and the raw materials of cold drawn seamless tubing can be generally identified. This method is called fracture identification method. There are five common fracture characteristics:

1) Medium carbon steel

The medium carbon steel cold drawn seamless tubing is easier to break than the low carbon steel, its fracture is silvery white, the contrast is flat, the particles are lower than the carbon steel finer, and there is no obvious plastic deformation phenomenon;

2) White cast iron

It is very easy to break, the fracture is bright white, and the grains are fine;

3) Grey cast iron

The gray cast iron cold drawn seamless tubing is simply knocked off, the fracture is dark gray, the grains are coarse, and the arrangement is relatively loose;

4) High carbon steel

The fracture is silver-white, the contrast is flat, there is no plastic deformation, and the particles are very fine;

5) Low carbon steel

Because the carbon content is low, the plasticity is good, and it is easy to be bent but not easily broken, it is usually necessary to saw the gap before knocking; the fracture of the low-carbon steel cold drawn seamless tubing appears silvery white, and the fracture can be seen at the fracture. Uniform particles, the fracture edge has obvious plastic deformation phenomenon.