... .0mm Standards: ASTM, BS, DIN, GB, JIS spring steel wire for mattressGrade:55CrSi,60Si2Mn,65Mn Dia:6.0~16.0mmStandards ... GB, JISAdvantage:1. Marerial: we select good quality spring steel wire rod.2. Surface treatment: advanced technology of shot blasting, 100 ... produce many kinds of strength level for spring steel wire. Mechanical property of steel wire in static level and Moderate fatigue level ...