Jim the springs used for tail wheels now a days are made from what is called "Blue Tempered Spring Steel" its not the true high carbon spring steel still used in trucks etc ,..don't heat it you will activate the atoms burning off what carbon is in it making it soft,,if you quench it it will become brittle

added: its better to bend a tail wheel spring then break it,..same with most of the light duty trailer springs,..they will bend before they break on most newer applications