... .0mm Standards: ASTM, BS, DIN, GB, JIS used mattress spring tempered spring steel wire Grade:55CrSi,60Si2Mn,65Mn Dia:6.0~16 ... BS, DIN, GB, JISAdvantage:1. Marerial: we select good quality spring steel wire rod.2. Surface treatment: advanced technology of shot ... zero defects for the surface.3. Quality assurance: Eddy current test online4.Service life: Ultra fine martensitic structure which could improve ...