Cold Rolled Steel Strip for Spring (IS : 2507-1965)
 
Designation of Steel Grade Tensile strength kgf/mm2 C % Si % Haedened in oil at oC Annealed at oC Typical Applications
Hardened and Tempered Annealed Max.
C 45 ... ... 1 120-145 60 0.40-0.50 0.10-0.35 830-860 600-650

In the form of bars and flats for volute, helical and leminated spring for automotive suspension
C 65 ... ... 3 120-145 60 0.60-0.70 0.10-0.35 810-840 600-650
C 75 ... ... 5 120-160 65 0.70-0.80 0.10-0.35 810-840 600-650
C 98... ... 8 160-180 70 0.90-1.05 0.10-0.35 770-800 620-660
55 Si 2
Mn 90 ...		 9 160-200 80 0.50-0.60 1.05-2.00 830-860 640-680
50 Cr I ... ... 10 170-230 80 0.45-0.55 0.10-0.35 830-860 640-680
50 Cr IV 23 11 190-240 80 0.45-0.55 0.10-0.35 830-860 600-680