Does anybody know any distributors of proprietary grade spring steel stronger than ASTM A401. The type of stuff used in the manufacture of valve springs and such...KOBE and Mitsubishi Steel are some producers of it in Japan.
I believe products from Kobe are available from both of these vendors. The following is a list of wire producers that offer valve quality spring steel in North America:
American Spring Wire (9MV is similar Kobe KHV7 [ASTM 877] & 90VN is similar to Kobe KHV10N)