Properties of Stainless Steel Rebar (grades, standards, properties, ...)
A steel qualifies as stainless if its chromium (Cr) content lies above 10.5%. Below this limit the passive layer is not sufficiently stable and protective for corrosive environments.
Standards
The main stainless steel rebar standards used today are BS 6744 (UK) [28] and ASTM A955 (USA) [29], although there are others such as XP135014 (France). Other countries just use the carbon steel standard, sometimes with minor adjustments, such as SIA 262 (Switzerland) or DIN 488(Germany).
Grades
|
Stainless Steel Type |
BS 6744 |
ASTM A955 |
ASTM A955 |
|
Austenitic with Mn |
- |
S24000 |
XM29 |
|
|
- |
S24100 |
XM28 |
|
Standard Austenitic |
1.4301 |
S30400 |
304 |
|
|
1.4436 |
- |
- |
|
|
- |
S31603 |
316 |
|
|
1.4429 |
S31653 |
316LN |
|
Duplex |
1.4162 |
- |
- |
|
|
1.4362 |
- |
- |
|
|
1.4462 |
S31803 |
- |
|
|
1.4501 |
- |
- |
|
Super Austenitic |
1.4529 |
- |
- |
Important notice: Other grades can be sold under CARES approval, of which grade EN 1.4482 (X2CrMnNiMoN21-5-3).
| BS 6744 Tensile properties |
0.2% Proof Strength Rp0.2 Mpa Min |
Stress Ratio Rm/Rp0.2 Min |
Elongation at Fracture, %, Min |
Total Elongation at Maximum Force, % Min |
| Grade 200 | 200 | 1.1 | 22 | 5 |
| Grade 500 | 500 | 1.1 | 14 | 5 |
| Grade 650 | 650 | 1.1 | 14 | 5 |
Tensile properties
|
ASTM A955 |
Grade 40 [280] |
Grade 60 [420] |
Grade 75 [520] |
|
Yield Strength, Mpa [ksi] Min |
280 [40] |
420 [60] |
520 [75] |
|
Tensile Strength, Mpa [ksi] Min |
500 [70] |
620 [90] |
690 [100] |
|
Elongation, % Min |
20 |
20 |
20 |
Stainless steel rebar is usually selected for the critical parts of the structure. There is no detrimental effect of using stainless steel and carbon steel together [30] [31] [31]
Guidance
Standard BS6744 [28] provides advice on the grades of stainless steel suitable for various service conditions:
Table B.1 - Guidance on the use of stainless steel reinforcement for different service conditions
|
Grade in accordance with BS EN 10088-1 |
Service condition |
|||
|
|
For structures or components with either a long design life, or which are inaccessible for future maintenance |
For structures or components exposed to chloride contamination with no relaxation in durability design (e.g. concrete cover, quality or water proofing treatment requirements) |
Reinforcement bridging joints, or penetrating the concrete surface and also subject to chloride contamination (e.g. dowel bars or holding down bolts) |
Structures subject to chloride contamination where reductions in normal durability requirements are proposed (e.g. reduced cover, concrete quality or omission of water proofing treatment) |
|
1.4301 |
1 |
1 |
5 |
3 |
|
1.4162 |
1 |
1 |
5 |
3 |
|
1.4436 |
2 |
2 |
1 |
1 |
|
1.4429 |
2 |
2 |
1 |
1 |
|
1.4362 |
2 |
2 |
1 |
1 |
|
1.4462 |
2 |
2 |
1 |
1 |
|
1.4529 |
4 |
4 |
4 |
4 |
|
1.4501 |
4 |
4 |
4 |
4 |
|
Key 1 – Appropriate choice for corrosion resistance and cost 2 – Over-specification of corrosion resistance for the application 3 – May be suitable in some instances: specialist advice should be obtained 4 – Grades suitable for specialist applications which should only be specified after consultation with corrosion specialists. 5 – Unsuitable for the application |
||||
Lean Duplex stainless steel grades (4162, 4362) are now increasingly used:
- They are now readily available
- In many cases they are the preferred option because they give the best performance for the capital cost.
Further reading
Guide for the use of stainless steel reinforcement in concrete structures (published in 2006) [32]
Guidelines For Shipping, Handling, Fabricating & Placement Of Stainless Steel Rebar [33]