1.blue tempered spring for rolling shutter 2.CK67,AISI 1065,1070,CS70 3.0.15~ ... , slit Blue Tempered spring steel strip for rolling shutter doorHeat treatment is carried out mainly for reducing sheet thickness, improving surface finishing ... Hardness as per client’s requestForms: Coils, Sheets, stripsApplications: Springs for shutter doorRaw Material: Baosteel CK67,CK75, SAE1065,SAE1070 CS60,CS70, C70 ...