What Is RSt37-2 Steel
RSt37-2 is a mild carbon structural steel defined in the German standard DIN 17100, which was withdrawn in 1997 and replaced by EN 10025-2. The designation breaks down as: RSt for rimming-quality structural steel, 37 for a minimum tensile strength of 370 MPa (37 kg/mm² in the old system), and 2 for the quality group. Its direct successor in modern practice is S235JR, which has essentially identical guaranteed properties.
Mechanical Properties
Yield strength - 235 MPa minimum for thickness up to 16 mm, per both DIN 17100 and the successor EN 10025-2 S235JR.
Tensile strength - 360-510 MPa depending on thickness, matching the 37 designation.
Elongation - minimum 22-26% depending on product form and test direction.
Weldability - carbon content around 0.17-0.20% maximum gives excellent weldability with no preheat in normal thicknesses.
Chemical Composition
Per DIN 17100, RSt37-2 limits carbon to 0.17% maximum for thickness up to 16 mm (0.20% up to 40 mm), phosphorus and sulphur to 0.050% each, and nitrogen to 0.007% when nitrogen-fixing elements are absent. The low carbon and impurity levels are the reason the grade welds, bends and forms so reliably, and why it remains popular for sheet and plate fabrication.
Use in Bridge Fabrication
RSt37-2 sheet has a long history in bridge construction, where its role continues through the S235JR equivalent:
Deck plates - roadway and walkway deck sheets spanning between girders.
Stiffeners and diaphragms - vertical and longitudinal stiffening of girder webs.
Connection plates - gussets, splice plates and bearing plates in secondary connections.
Parapets and ancillary steel - handrails, kerbs and maintenance access steelwork.
For main load-carrying bridge members in modern design, higher grades such as S355 are preferred; RSt37-2 and S235JR remain the economical choice for secondary and ancillary steel.
Supply Forms
The steel is supplied as hot rolled sheet and plate from 1.5 mm to 100 mm thick, in widths to 2500 mm and lengths to 12000 mm, with mill edge or cut edge. Surfaces are available as rolled, pickled and oiled, or shot blasted and primed. Mill test certificates per EN 10204 type 3.1 can state equivalence to EN 10025-2 S235JR where the project accepts it.
Frequently Asked Questions
Q: Is DIN 17100 still valid?
No, DIN 17100 was withdrawn and replaced by EN 10025-2; RSt37-2 is now supplied as S235JR with equivalent properties.
Q: What does the 37 in RSt37-2 mean?
It refers to the minimum tensile strength of 370 MPa in the older kg/mm² based designation system.
Q: Can RSt37-2 be used for bridge main girders?
For secondary and ancillary steel yes; modern bridge main girders normally use higher-strength grades such as S355.
Q: Is RSt37-2 easy to weld?
Yes, its low carbon content makes it one of the most weldable structural steels, with no preheat required in normal thicknesses.
Q: What thickness range is available?
Sheet and plate from 1.5 mm to 100 mm are available, with cutting to size and surface treatment on request.
Q: Do you provide mill certificates?
Yes, mill test certificates per EN 10204 type 3.1 are provided with each delivery.