Hello submero,

I haven't looked at your model, but you didn't fix the problem that causes the model to fail at 1.35.  The elements in the bolt head are too large. You need to add a mesh control to create smaller elements on the contact face of the bolt head. Currently there are 2 elements across the contact face. Make sure there are at least 4 elements across the width of that face. Same on the Nut face.

After you make that change, if the solver fails to converge, please reply with the N-R Force Convergence Plot and the N-R Residual Force Plots and their details window to see where the solver is having difficult converging. Once you know which part and where on that part, the corrective action is to use smaller elements.

Let me know what you find.