None of the cutting variations appear to be statistically significant. However, overall, cutting setting 1 seems slightly better, meaning the bending angle is a bit lower, which is good: the material can bend a bit more.
We also tested pre-straining the materials to 2% and 4% plastic deformation. To get a more detailed explanation of the tests, please watch the on-demand webinar. Our conclusions were that pre-straining decreases formability, lowering the CF max and increasing the CF angle.
Next, we wanted to use our new bending test to determine the cut edge ductility of different steel grades. Samples were 20mm tall, the knife radius was 10mm (except for the 800 steel, which used a 5mm punch), cutting clearance was 10% at a low cutting angle, and the cut was longitudinal to the rolling direction.
For possible use in forming simulations, we focus on the CF-Max value, as shown in Figure 18.
But if our focus is on making big parts or complex shapes, we’ll look at the CF-Angle, the necking angle, as shown in Figure 19.
If you have a low CF-Angle, then it means that you can make a big complicated bend of that material. So here it's clear that the HR800HER100 material is better than the HR800HER75 material.