... 4.round, slit Blue Tempered spring steel strip for rolling shutter doorHeat treatment is carried out mainly for reducing sheet thickness ... as per client’s requestForms: Coils, Sheets, stripsApplications: Springs for shutter doorRaw Material: Baosteel CK67,CK75, SAE1065,SAE1070 CS60,CS70, C70 ... Coil: < 20”, 50.8cmO.D. Coil: < 60”, 152.4cmMax weight: < 6,000 lbs, 2727 kgs blue tempered spring for rolling ...