ST37 vs ST52 vs S355 Carbon Steel: Complete Comparison Guide

When sourcing structural carbon steel for international projects, three grades appear frequently in purchase specifications: ST37, ST52, and S355. While all three are carbon-manganese structural steels, their properties, standards, and applications differ significantly. Making the wrong choice can lead to rejection at inspection, project delays, or worse — structural failure.

This guide compares ST37, ST52, and S355 across every dimension that matters for procurement: chemistry, mechanical properties, international equivalents, available forms, and practical selection criteria.

Quick Comparison: ST37 vs ST52 vs S355

Property	ST37 (DIN 17100)	ST52 (DIN 17100)	S355 (EN 10025-2)
Standard	DIN 17100 (obsolete, replaced by EN 10025)	DIN 17100 (obsolete, replaced by EN 10025)	EN 10025-2 (current European standard)
Modern Equivalent	S235JR	S355J2 / S355JR	S355J2 / S355JR / S355K2
Minimum Yield (MPa)	235	355	355
Tensile Strength (MPa)	360-510	490-630	470-630
Carbon Content (max %)	0.17	0.20	0.20 (JR), 0.22 (J0/J2)
Weldability	Excellent	Good (preheat for thick sections)	Good to Excellent (depending on subgrade)
Typical Application	General structures, light fabrication	Heavy structures, bridges, cranes	Bridges, offshore, heavy machinery
Price Index (relative)	1.0 (baseline)	1.15-1.25	1.10-1.20

Chemical Composition Comparison

Element (wt%)	ST37-2 (S235JR)	ST52-3 (S355J2)	S355J2+N	S355K2+N
Carbon (C)	≤0.17	≤0.20	≤0.20	≤0.20
Silicon (Si)	≤0.35	≤0.50	≤0.55	≤0.55
Manganese (Mn)	≤1.40	≤1.80	≤1.70	≤1.70
Phosphorus (P)	≤0.035	≤0.035	≤0.030	≤0.025
Sulfur (S)	≤0.035	≤0.035	≤0.025	≤0.020
Nitrogen (N)	≤0.012	≤0.012	≤0.012	≤0.012
CEV (typical)	≤0.35	≤0.45	≤0.45	≤0.45

Key observation: ST52 and S355 have similar carbon and manganese ranges. The distinction lies in the delivery condition and subgrade — S355J2 delivers guaranteed impact properties at -20°C, while ST52-3 (the closest matching subgrade) guarantees to -20°C as well when specified as normalized.

EN 10025 S355 Subgrades Explained

One of the most common points of confusion for buyers is the S355 subgrade designation. Here is what each suffix means:

Designation	Impact Temperature	Min. Impact Energy	Delivery Condition
S355JR	+20°C	27J	As-rolled (AR)
S355J0	0°C	27J	As-rolled or normalized
S355J2	-20°C	27J	As-rolled or normalized
S355K2	-20°C	40J	Normalized or TMCP
S355NL	-50°C	27J	Normalized

Procurement tip: When a specification says “ST52” without a subgrade, always clarify whether JR (room temperature) or J2 (-20°C impact) is required. The price difference can be 8-12%, and ordering the wrong subgrade is one of the most frequent reasons for material rejection at port.

Mechanical Properties by Thickness

Thickness (mm)	ST37 Yield (MPa)	ST37 Tensile (MPa)	ST52/S355 Yield (MPa)	ST52 Tensile (MPa)	S355 Tensile (MPa)
≤16	235	360-510	355	490-630	470-630
16-40	225	360-510	345	490-630	470-630
40-63	215	360-510	335	490-630	470-630
63-80	215	360-510	325	490-630	470-630
80-100	215	360-510	315	470-610	470-610
100-150	195	350-500	295	450-590	450-590

Important: The thickness-dependent yield strength reduction applies to all three grades. When specifying S355 for thick sections (above 40mm), the actual minimum yield will be lower than 355 MPa. Always reference the MTC for the specific thickness supplied.

International Grade Equivalents

Region	ST37 Equivalent	ST52 / S355 Equivalent
Europe (EN)	S235JR	S355J2 / S355JR
USA (ASTM)	A36, A283 Gr.C	A572 Gr.50, A572 Gr.55
Japan (JIS)	SS400	SM490A, SM490YA
China (GB/T)	Q235B	Q355B, Q345B
India (IS)	IS 2062 E250	IS 2062 E350
Russia (GOST)	St3sp	17G1S, 10G2S1

Delivery Conditions and Impact on Performance

The delivery condition significantly affects both mechanical properties and price:

As-rolled (AR): The most economical option. Suitable for ST37/S235 and S355JR — not suitable for sub-zero applications.
Normalized (N/+N): Heat treated to refine grain structure. Required for S355J2+N and thicker sections. Adds approximately 5-8% to cost but delivers guaranteed impact properties at -20°C.
Thermomechanically rolled (M/+M): Controlled rolling process achieving fine grain without normalizing. Common for S355M/ML grades. Lower carbon equivalent for better weldability.
Quenched and tempered (QT): For special high-strength applications. Not typical for standard ST37/ST52/S355 procurement.

When to Choose ST37 (S235JR)

Choose ST37/S235JR when:

The structure is lightly loaded (secondary beams, bracing, handrails, platforms)
Excellent weldability without preheat is the priority
Budget is the primary constraint and strength requirements are modest
The application does not require impact testing at low temperatures
The project is for general fabrication — machine frames, storage racks, enclosures

When to Choose ST52 (S355J2)

Choose ST52/S355J2 when:

The structure carries significant loads (primary beams, columns, crane girders)
The project requires guaranteed impact properties at -20°C
High strength-to-weight ratio is needed (offshore platforms, mobile equipment)
Fatigue resistance is a design consideration
The specification explicitly calls for EN 10025 S355J2 or equivalent

Practical Procurement Checklist

When issuing a purchase order for ST37, ST52, or S355, include these details to ensure you get what you need:

Exact grade and subgrade: Not just “ST52” but “S355J2+N per EN 10025-2:2019”
Delivery condition: As-rolled, normalized (+N), or TMCP (+M)
Impact test temperature: Confirm the subgrade matches the required test temperature
CEV limit: Specify maximum carbon equivalent value for weldability (CEV ≤ 0.45 typical)
Mill test certificate: Request EN 10204 Type 3.1 MTC with full chemistry and mechanicals
Third-party inspection: Specify if SGS, BV, TUV, or other inspection is required before shipment
Tolerances: Reference EN 10029 for plate tolerances or EN 10034 for sections

FAQ

Is ST52 the same as S355?

ST52-3 is the closest DIN 17100 predecessor to EN 10025 S355J2. The chemical composition and mechanical properties are nearly identical. However, S355 has additional subgrades (JR, J0, J2, K2, N, NL, M, ML) that ST52 does not. When a specification calls for “ST52,” the modern equivalent is S355J2+N — but always confirm the required impact test temperature.

Can ST37 and S355 be welded together?

Yes, ST37 (S235) and S355 can be welded together using standard E7018 or ER70S-6 filler metal. The weld procedure should be qualified for the higher-strength material (S355). Preheat is typically not required for sections under 30mm when using low-hydrogen electrodes. Always follow the welding procedure specification (WPS) qualified for the joint configuration.

Why is ST52 more expensive than ST37?

ST52/S355 commands a 15-25% premium over ST37/S235 due to higher manganese and microalloy content, more stringent processing controls (especially for normalized grades), additional impact testing, and lower production yield rates. The normalized condition (+N) adds another 5-8% versus as-rolled S355JR.

What thicknesses are available for these grades?

Standard plate thickness ranges from 6mm to 150mm for ST37 and ST52/S355 in as-rolled condition. Normalized S355J2+N is available from 8mm to 250mm. Hot-rolled sections (beams, channels, angles) are available in ST37/S235 and S355 up to HE1000M / IPE600. For thicknesses above 150mm, consult the mill for specific availability and lead time.

Do I need impact testing for indoor applications?

If the structure is indoors in a climate-controlled environment, S355JR (impact at +20°C) may suffice. However, if the steel will be transported through cold regions, erected in winter conditions, or used in unheated buildings in temperate climates, S355J0 (0°C) or J2 (-20°C) is strongly recommended. The marginal cost for J2 over JR is typically 3-5% — a small premium for safety-critical insurance.

Conclusion

ST37, ST52, and S355 serve distinct roles in structural engineering. ST37 (S235JR) is the economical workhorse for general fabrication. ST52 (S355J2) is the standard for load-bearing structures requiring guaranteed low-temperature toughness. S355 provides the most flexible subgrade system, allowing precise specification of impact properties, delivery condition, and weldability. The key to successful procurement is being specific — always quote the exact EN 10025 designation, subgrade, delivery condition, and required documentation to your supplier.

Need ST37, ST52, or S355 carbon steel in plate, section, or bar form? Contact Huaxia-Steel for factory-direct pricing, full EN 10204 3.1 mill certification, custom dimensions, and global shipping from our network of ISO-certified mills.