Research on Joining High Pressure Die Casting Parts by Self-Pierce Riveting (SPR) Using Ring-Groove Die Comparing to Heat Treatment Method

Nowadays, the increasing number of structural high pressure die casting (HPDC) aluminum parts need to be joined with high strength steel (HSS) parts in order to reduce the weight of vehicle for fuel-economy considerations. Self-Pierce Riveting (SPR) has become one of the strongest mechanical joining solutions used in automotive industry in the past several decades. Joining HPDC parts with HSS parts can potentially cause joint quality issues, such as joint button cracks, low corrosion resistance and low joint strength. The appropriate heat treatment will be suggested to improve SPR joint quality in terms of cracks reduction. But the heat treatment can also result in the blister issue and extra time and cost consumption for HPDC parts.

The relationship between the microstructure of HPDC material before and after heat treatment with the joint quality is going to be investigated and discussed for interpretation of cracks initiation and propagation during riveting. The SPR joint quality will be evaluated based on interlock distance, the minimum remaining thickness (T_min), shear strength etc. Instead of using heat treatment method, the SPR joints formed by the special die set with ring-groove design will be tested and the joint quality will also be covered. The crack suppression mechanism is going to be included in the SPR simulation done by FORGE. The significance of the ring-groove die design from Böllhoff for joining HPDC aluminum parts in as-cast condition will be discussed in order to improve the joint quality and reduce manufacturing cost.