Materials used:
° Unalloyed spring steel wire acc. to DIN EN 10270-1:
  types SL / SM / SH / DH (formerly grades A,B,C,D)

° Unalloyed spring steel wire acc. to DIN EN 10270-1: 
  pre-galvanised types SL(z) / SM(z) / SH(z) / DH(z)

° Unalloyed spring steel wire acc. to DIN 17223-1:1964 II:
  (formerly Class II)

° Quenched and tempered spring wire acc. to 
  DIN EN 10270-2:
  SiCr-alloyed / e.g. FD54SiCr6 standard strength / high
  strength / super high strength 
  
° Valve spring wire acc. to DIN EN 10270-2:
  SiCr-alloyed / e.g. VDSiCr super clean, peeled,
  crack-tested

° Stainless steel spring wire acc. to DIN EN 10270-3:
  e.g. 1.4310 / 1.4571 / 1.4568 / 1.4401

° Special materials for high-temperature applications:   
  e.g. 2.4669 (Inconel X750) / 2.4668 (Inconel X718)
  e.g. 2.4632, 2.4969 (Nimonic 90)
  e.g. 2.4610 (Hastelloy C-4)