Do you know the cause of cracking of the crimp nut

Update:19 Jan 2020
Summary:

The main reasons for the cracking of crimping nuts are […]

The main reasons for the cracking of crimping nuts are the increase of medium carbon and alloy elements in the material, and the higher hardness and strength of the raw materials will cause the crimping nuts.
The raw material material has a poor structure, with material segregation and poor annealed structure, which increases the difficulty of cold heading deformation and increases the possibility of product cracking.
The increase in the complexity of the shape of the fastener will also bring certain difficulties to deformation and increase the risk of product cracking;
If the equipment and mold are not matched, the possibility of cracking of the product of the crimping nut, crimping nut, and crimping screw will increase; the number of inclusions in the material will increase, and the number of inclusions will increase, exceeding the standard grade range, which will cause cold heading cracking. One of the most important reasons.
Steel has many non-metallic inclusions, weird shapes, dense distribution, large size, and string distribution. In addition, the inclusions are branched and connected with dots to form a piece. This is a major cause of cold heading cracks in fasteners. . v
Cracks are caused by poor materials, mainly because the inclusions in the material are widely distributed, with large particles and dense distribution, all exceeding the technical requirements.
Spots are areas where the inclusions are densely distributed in the material. The material in the area where the inclusions are concentrated breaks the inherent consistency and continuity of the material. The plasticity of the material is severely reduced. When the external force increases, the area where the inclusions are concentrated cannot accept the product. The huge squeezing force during deformation is in the area where the inclusions are continuously destroyed along the line, and the stress is concentrated in the distribution area. The weak link of the material is torn first, forming the cracking phenomenon of the finished product.