Round Seamless DOM Steel Tube BS 6323-4 CFS 3 / CFS 3A / CFS 4

Designation

C

%

Si

%

Mn

%

P(Max)

%

S(Max)

%

Cr

%

Mo

%

0.20 max

0.35 max

0.90 max

0.20 max

0.25 max

0.35 max

1.20 max

0.23 max

0.50 max

1.50 max

0.35 max

0.35 max

0.35 max

0.29 max

0.35 max

1.50 max

0.26 max

0.35 max

0.80 max

0.45 max

0.35 max

1.00 max

Designation

BK^d

^{(cold finished/hard)}

BKW^d

^{(cold finished/soft)}

GBK and GZF

(annealed)

NBK amd NZF

(normalized)

R_e

min

N/mm²

R_m

min

N/mm²

A

min

%

R_e

min

N/mm²

R_m

min

N/mm²

A

min

%

R_e

min

N/mm²

R_m

min

N/mm²

A

min

%

R_e

min

N/mm²

R_m

min

N/mm²

A

min

%

Note: Welding of tubes of grades 3, 3A, 4 and 5 does not require special techniques but care should be taken and welding carried out in accordance with the guidance given in the appropriate British Standard for welding, e.g. BS 5135. The welding of other grades shown may require special technique.

^a Grade 3A shall be suitable for case hardening purposes.

^b Grain refining elements may be added at the option of the manufactures.

^c Steels within the limits shown, but in accordance with the chemical composition of BS 970-1, may be supplied if agreed at the time of order or enquiry.

^d If tubes in the BK and GKW condition are subsequently welded, braced or heated the mechanical properties in the heat affected zone may be reduced to those given for the delivery condition GBK or NBK.