Elastic Deformation Question

[matt4]

Not sure really where to put this but... I am having some problems with some of my graphs. I did a tensile test on some materials and two of them are giving me a headache

I can't redo these tests. The first material is Nylon 66 Glassfilled. Unfortunately it appears to have no elastic region and immediately deforms. I need to pull the stress at yield from this graph but this is a real problem because I cannot identify where the region is! I am haivng the same problem with Mild Steel.

I have attached the two images here. If someone can explain where the elastic region is on these graphs or what I should do I would be grateful!

Thanks