Chemical composition and mechanical properties of stainless steels to BS 6744

Introduction

BS 6744 Stainless steel bars for the reinforcement of and use in concrete was last published in 2009. This version is substantially the same as the 2001 edition but with the addition of 2 lean duplex steels 1.4162 and 1.4362.  These steels have the benefit of having a lower nickel content than the standard austenitic grades such as 1.4301 and 1.4401. They are therefore less prone to large variations in price.

The grade designations are harmonized with the European steel number system, but currently there is no European standard for these products.
The steels included in BS 6744 can also be found in BS EN 10088-3. The specified composition ranges are the same, but with some differences in the number of decimal places for the percentages of some elements shown. The ranges are however shown in this article. The tensile properties are also included in this article, but these are not expressed in the same way as in BS EN 10088-3, the general standard for stainless steel bars. The strength levels for bars to BS 6744 are expressed as the 'Grade' and indicate the proof strength of the steel. Guidance on steel number selection in a range of service environments is given in Annex B of the standard.

This information is summarized in the BSSA Special Report 'The use of stainless steel reinforcement in bridges'

The data given is not intended to replace that shown in individual standards to which reference should always be made.

BS 6744 chemical composition table

Grade
Chemical composition (% by mass - max unless stated)
- C Si Mn S Cr Ni Mo P N
1.4301 0.07 1.0 2.0 0.03 17.0/19.5 8.0/10.5 - 0.045 0.11
1.4436 0.05 1.0 2.0 0.015 16.5/18.5 10.5/13.0 2.5/3.0 0.045 0.11
1.4429 0.03 1.0 2.0 0.015 16.5/18.5 11.0/14.0 2.5/3.0 0.045 0.12/0.22
1.4162 0.04 1.0 4.0/6.0 0.015 21.0/22.0 1.35/1.75 0.1/0.8 0.040 0.20/0.25
1.4362 0.03 1.0 2.0 0.015 22.0/24.0 3.5/5.5 0.1/0.6 0.035 0.05/0.20
1.4462 0.03 1.0 2.0 0.015 21.0/23.0 4.5/6.5 2.5/3.5 0.035 0.10/0.22
1.4501 0.03 1.0 1.0 0.015 24.0/26.0 6.0/8.0 3.0/4.0 0.035 0.20/0.30
1.4529 0.02 0.50 1.0 0.010 19.0/21/0 24.0/26.0 6.0/7.0 0.030 0.15/0.25

Note
Nitrogen contents of grades 1.4301 and 1.4436 may be increased to 0.22% max

BS 6744 tensile property table

Grade
Tensile Properties (min unless stated)
- 0.2% Proof strength, Rp0.2 Stress Ratio, Rm/Rp0.2 Elongation at fracture, A5 Total elongation at maximum force, Agt
 
200 200 1.10 22 5
500 500 1.10 14 5
650 650 1.10 14 5

Note
Proof strength and stress ratio units are MPa (N/mm2)
Elongation values are percentages (%) (Elongation is A5, total is Agt)

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