Rivet result after riveting

[sathishk123]

Good morning...
We using EN1A material for riveting . Its hardness getting at a band of 50 - 105 HRB .
After riveting we getting 3 types of results
1)HRB 95-100 - rivet crack
2)HRB 80-95 - Rivet ok as per our requirement
3)HRB 60-75 - Rivet not complete height more and OD less
Need brief explanation on this.

 

[TVP]

Rivets require closer hardness/strength control than 50-105 HRB. A typical hardness specification is 76-85 HRB for critical rivets (Grade 3 in SAE J430).