Im having trouble finding anything on what a SWPA material is and what the key properties of it. I've seen a few springs claiming to be made of SWPA, but I still have no idea what it means. Any help is greatly appreciated!
SWP-A is a designation for patented, cold drawn spring steel wire according to JIS G3521 and G3522. It is used for static applications, similar to ASTM A227 or SL/SM/SH according to EN 10270-1. Here are two links for more information: