Defects in Metal Material Forming Processing, Part 6

Defects in metal forming processes can arise due to various factors, including material properties, process parameters, and environmental conditions. Here are some common defects associated with metal forming:

Delamination

Gaps appear in the thickness direction of the product, and the corresponding processing direction is separated into layers.

The contact between the layers is flat and the area is large. Some have oxides or inclusions, which often appear in thin strips or after welding. Fracture delamination will also occur during the fracture inspection of tubes and bars.

The main reasons for delamination are: there are defects such as pores, shrinkage cavities, shrinkage, inclusions, etc. in the ingot, which form delamination after processing;

the hot rolling pass of the plate and strip is improperly distributed, and the reduction is too large; the ingot is heated unevenly, and the heating temperature is too high or too low;

the extrusion barrel or piercing needle of the tube and bar is over-lubricated, the piercing needle has cracks, or the shrinkage tail of the extruded product is not cut cleanly, and delamination is formed after further stretching and rolling.