"When you agree to the copyright form" => presumably this is different for every publisher.
My only pre-print (hosted on arXiv) was submitted there long before it was accepted for publication in a non-Elsevier journal, who have made no attempt to take it down.
There are also open access journals which explicitly allow you to host your own pre-prints.
My only pre-print (hosted on arXiv) was submitted there long before it was accepted for publication in a non-Elsevier journal, who have made no attempt to take it down.
There are also open access journals which explicitly allow you to host your own pre-prints.