the discovery
The accumulated efforts of several individuals as far back as 1821 lead to the discovery of stainless steel in 1913 in Sheffield, England. The first major known structure is the shipping pier in Progreso Mexico in operation since 1941.
What is Stainless Steel Reinforcement
Stainless steel rebar is a round bar used to reinforce various types of reinforced concrete structures in a range of applications.
CORROSION RESISTANCE & APPLICATIONS
Known for its corrosion resistance top ranking, applications include all types of concrete structures where the service conditions are corrosive due to chloride attack (road salt, marine spray) or other chemicals.
The applications encompass the entire range of structures exposed to chloride or chemical attack. They include structures such as
highway bridges and other transportation infrastructure,
road and rail tunnels,
parking garages,
water and sanitation facilities,
chemical plants,
preservation of historic / iconic structures, and
structures exposed to marine conditions.
For additional information, see Guidance on stainless use for corrosion.
MATERIAL PROPERTIES
The broad mix of other material properties provide designers with the ideal steel reinforcement for many applications and/or design benefits.
| Material Properties | Applications |
|---|---|
| Extensive fatigue resistance | Seismic and other cyclic loading conditions |
| Low temperature toughness, maintaining yield strength (high Charpy values) | LNG, other cryogenic uses and other cold temperature uses |
| Maintain yield strength at high temperatures | High temperature uses, fire rating |
| Low magnetic permeability | MRI’s, housing for sensitive electronics |
| Radiation resistance | Nuclear Containment |
| A955 Grade 80, high yield strength | Design savings |
For additional information, go to Guidance on other uses of stainless.
Also see Properties of Stainless Steel Rebar for more information.
Contact us for more information.
stainless steel Chemistry
Stainless steels are iron-based alloys which ASTM A941 (2010b) defines as containing a minimum chromium content of 10.5 percent.
The commonly used types of rebar have about twice the minimum chromium content and a carbon content of 0.03 percent, making them virtually “carbon free”, and therefore much less prone to corrosion.
Besides chromium, typical alloying elements are nickel, molybdenum, manganese and nitrogen which together make up almost 35% of the total chemistry by weight.
superior corrosion resistance : explained
It’s about the exceptional levels of chromium as part of an alloy mix of 35% by weight, and very low carbon.
The key factor is sustainable passivity of the stainless steel cathode.
Like no other material, A955 alloys form a robust, stable, transparent, passive and adherent surface film of chromium oxide. This film spontaneously forms and regenerates to protect the surface of the metal from corrosive attack.
The oxide layer regenerates only at a critical chromium content at/above 10.5%. No other rebar does this.
Below 10.5%, the passivity layer is weak and is not sustainable. Non-stainless bars will “stain” with rust. Corrosion sets in rapidly.
The heightened level of passivity prevents galvanic coupling, or corrosion cell formation with other less passive steel materials in the concrete. It inhibits corrosion formation.
Superior chemistry drives the durability and extended superior service life of structures exposed to corrosive elements.
Contact us for more information.
ASTM A955 – The Stainless Standard
The governing manufacturing guide for SSR is the international industry standard is ASTM A955/A955M – Standard Specification for Deformed and Plain Stainless Steel Bars for Concrete Reinforcement.
There are many similarities compared to conventional rebar standards such as the bar sizes, bend diameters and high strength Grade 80 yield steel.
There are two classifications based on the microstructure in A955 :
the duplex alloys, consisting of austenitic-ferritic microstructures
and the austenitic alloys
Common Sizes
Of all the alloys in A955, there are only four that of which are commonly used. In order of preference they are :
2304 (duplex)
2205 (duplex)
316ln (austenitic), and
XM-28 (austenitic)
The broad number of alloys allows the designer to “custom” fit the right alloy to the design requirements.
Contact Us for information on A955’s unique content.
guidANCE on STAINLESS use for corrosion
The licensed design engineer will have to take into account many factors in selecting the appropriate type of stainless steel rebar alloy.
They include the severity of the environmental exposure conditions, the type of exposure, the usage patterns, the extent to which major repairs and their frequency can be tolerated, and the expected service life required by the Owner.
|
Alloy Type |
Marine or Harsh Chemical |
Severe Chloride |
Mild Chloride |
|---|---|---|---|
| 2304 | No | Yes | Yes |
| 2205 | Yes | Yes | Yes |
| 316LN | Yes | Yes | Yes |
| XM-28 | No | No | Yes |
For more information on Guidance : Contact Us
| Design / Exposure Conditions | ||||||
|---|---|---|---|---|---|---|
| Alloy |
Low Magnetic Permeability |
Controlled Mechanical Properties |
Seismic Uniform Elongation, Ductility, Fatigue |
Low Temperature Toughness |
Radiation Resistance |
Yield Maintenance High & Low Temperature |
| 2205 | No | Yes | Exceptional | Exceptional | High | Very Good |
| 2304 | No | Yes | Exceptional | Exceptional | High | Very Good |
| 316LN | Yes | Yes | Exceptional | Exceptional | High | Very Good |
| XM-28 | Yes | Yes | Exceptional | Exceptional | High | Very Good |
GUIDANCE on other uses for stainless
The choice of alloy is dependent on the design service conditions for other applications such as those related to extreme cyclic loading and fatigue resilience (seismic), low temperature (cryogenic/LNG) maintenance of yield and material toughness (Charpy), or magnetic permeability (shield sensitive electronics).
Click here for a table on Other uses for Stainless
Product Manufacturing
Our SSIG mill, North American Stainless, applies modern up to date technologies for steel making using 90% recycled scrap material.
Contact Us for more information about the process.
Buy America build america
In the United States, for public authorities to obtain federal funding for infrastructure projects, both the production of the ingots used to manufacture the stainless steel reinforcement material and the process of rolling of the bars must have been performed in the U.S.A.
The stainless steel rebar materials available from the members of SSIG guarantee that the rebar meets these BABA requirements.
rebar data sheets
Data sheets for the four commonly used stainless steel rebar alloys meeting the standard ASTM A955 can be accessed here.
Accessories : Couplers, Tie wire data sheets
Information on stainless steel couplers and tie wire are readily available from the stainless steel rebar fabricators.
Click here for coupler data sheets.
File : “Resources_SSIG website_Rev1”
Section : Material Technical Data Sheets : Couplers