How to view the dry cracking of powder metallurgy products

Do you know what causes dry cracking in powder metallurgy products? Before the powder metallurgy product calcination process, the entire process of forming inhibition or production processing should be carried out. The main reason for the product to dry and crack during this process is likely to be poor adhesion between particles before calcination, and the ground stress caused by calcination may "open" cracks, but this is likely to have already occurred in the processing process before calcination. So, what is the reason for dry cracking of powder metallurgy products? Shenzhen Ridong High tech Professional and Technical Personnel will answer for everyone:

1. Movement between particles:

The bonding between particles was initially mainly caused by brittle fracture and fitness exercise of powdery blocks. In an ideal environment, the densification process is bidirectional, symmetrical, and total synchronous, without causing movement between particles. The movement of the school after the entire densification process will hinder the adhesion between particles and can destroy the initial adhesion formed.

2. High support force and shear stress:

In the case of powder metallurgy billets, if the supporting force of the formed body is caused by external or internal factors, and the shear stress is higher than the compressive strength of the formed body itself, it will crack.

3. Incorrect raw material dominance:

Additives are used in metal powders for various reasons. For example, mixing appropriate lubricants can also increase expansion and reduce mold force. However, mixing fans and excessive lubricants can hinder the bonding between particles, and adhesives, residues, and even residual gases can have a negative impact on the bonding.

4. Abnormal plastic strain separation during the forming process:

The shape of particles will undergo irreversible changes. In addition, recoverable shape changes may occur. Finally, during the molding process, the relevant pressure will also decrease to zero. When the pressure of the forming work is released, the compressive stress is released, and the billet on the surface of the formed body may suddenly transition from plasticity to elasticity. If the thermal stress exceeds the yield limit of the formed body, cracks will occur.

The above is about the reasons for dry cracking of powder metallurgy products. The potential cracks in powder metallurgy products have long been referred to as cracks with significant impact, often becoming a limiting factor for the application of powder metallurgy technology in the manufacturing of parts with complex appearances.