mattress and spring Grade:55CrSi,60Si2Mn,65Mn Dia:6.0~16.0mm Standards: ASTM, BS, DIN, GB, JIS mattress and ... GB, JISAdvantage:1. Marerial: we select good quality spring steel wire rod.2. Surface treatment: advanced technology of ... to produce many kinds of strength level for spring steel wire. Mechanical property of steel wire in ... .001430~15801400~15501500~16501630~17801740~18903540 mattress and spring