Designation of steel on the basis of mechanical properties

Symbols for:

a) Method of deoxidation

• R = Rimmed steel
• K= Killed Steel
• No Symbol = Semi Killed Steel

b) Quality of steel

• Q1 = Non-ageing quality
• Q2 = Freedom from flakes
• Q3 = Given size controlled
• Q4 = Inclusions controlled
• Q5 = Internal homogeneity guaranteed

c) Sulphur and Phosphorus content

• When maximum S and P content is same

No symbol - 0.055% P and 0.055% S

P 25 - 0.025% P and 0.025% S

P70 - 0.07% P and 0.07% S

• When maximum contents of S and P are not same, symbol SP shall be used.

d) Weldability guarantee

• W- Fusion weldable steel
• W1- Steel weldable by resistance welding but not fusion weldable.

e) Resistance to brittle fracture (Based on V-notch charpy impact test)

f) Surface condition

• S7 = Ground
• S6 = Bright drawn or cold rolled
• S5 = Peeled
• S4 = Shot, grit or sand blasted
• S3 = Pickled
• S2 = Descaled
• S1 = Deseamed or scarfed
• No symbol = As rolled or as forged

g) Formability

• D1 = Drawing quality
• D2 = Deep drawing quality
• D3 = Extra deep drawing quality
• No symbol = Steel is of commercial quality
• h) Surface Finish (for sheets only)
• F1 = General Purpose finish
• F3 = Exposed
• F2 = Full Finish
• F4 = Unexposed
• F5 = Matt Finish
• F6 = Bright Finish
• F7 = Plating finish
• F8 = Unpolished finish
• F9 = Polished finish
• F10 = Polished & colored blue
• F11 = Polished and colored yellow
• F12 = Mirror finish
• F13 = Vitreous enamel finish
• F14 = Direct annealed finish

i) Treatment

• No symbol - Hot rolled
• T1 = Shot peened
• T2 = Hard Drawn
• T3 = Normalized
• T4 = Controlled rolled
• T5 = Annealed
• T6 = Patented
• T7 = Solution treated
• T8 = Solution treated and aged
• T9 = Controlled cooled
• T10 = Bright annealed
• T11 = Spherodized
• T12 = Stress relieved
• T13 = Case Hardened
• T14 = Hardened and tempered

j) For elevated temperature properties, letter 'H' is used.

k) For low temperature (cryogenic properties), the letter 'L' is used.