The difference is mainly in the rolling and cooling techniques, which affect mechanical properties such as yield strength and tensile strength.
In steel construction, especially non-residential construction, S235 was the standard for many years. But given its advantages, the switch to S355 is obvious, right?
What grade of steel is S355?
Technical information. S355 Structural steel grades are carbon-manganese steels with guaranteed minimum mechanical properties (yield strength and tensile strength) and with satisfactory ductility. Structural steels offer good weldability with all conventional welding processes.
Mechanical properties:
| EN Standard | Designation | Direction | Thickness | Re | Rm | A 5.65√So | KV 20°C | KV 0°C | KV -10°C | KV -20°C | KV -30°C | KV -40°C | KV -50°C | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| EN 10027-1 | EN 10027-2 | (mm) | (MPa) | (MPa) | (%) | (J) | (J) | (J) | (J) | (J) | (J) | (J) | ||
| EN 10025-2 | S355 | L | 5-120 | JR | J0 | J2 | ||||||||
| ≥27 | 27 | ≥27 | ||||||||||||
| K2 | ||||||||||||||
| ≥40 | ||||||||||||||
| T | 5-16 | ≥355 | 470-630 | ≥20 | ||||||||||
| 16-40 | ≥345 | |||||||||||||
| 40-63 | ≥335 | ≥19 | ||||||||||||
| 63-80 | ≥325 | ≥18 | ||||||||||||
| 80-100 | ≥315 | |||||||||||||
| 100-120 | ≥295 | 450-600 | ||||||||||||
| EN 10025-3 | S355N | 1.0545 | L | 5-120 | - | - | - | ≥55 | ≥47 | ≥43 | ≥40 | |||
| T | 5-16 | ≥355 | 470-630 | ≥22 | ≥31 | ≥27 | ≥24 | ≥20 | ||||||
| 16-40 | ≥345 | |||||||||||||
| 40-63 | ≥335 | |||||||||||||
| 63-80 | ≥325 | ≥21 | ||||||||||||
| 80-100 | ≥315 | |||||||||||||
| 100-120 | ≥295 | 450-600 | ||||||||||||
| S355NL | 1.0546 | L | 5-100 | - | - | - | ≥63 | ≥55 | ≥51 | ≥47 | ≥40 | ≥31 | ≥27 | |
| T | 5-16 | 470-630 | ≥22 | ≥40 | ≥40 | ≥34 | ≥30 | ≥27 | ≥23 | ≥20 | ≥16 | |||
| 16-40 | ||||||||||||||
| 40-63 | ||||||||||||||
| 63-80 | ≥21 | |||||||||||||
| 80-100 | ||||||||||||||
| EN 10025-4 | S355M | 1.8823 | L | 5-60 | - | - | - | ≥55 | ≥47 | ≥43 | ≥40 | |||
| T | 5-16 | ≥355 | 470-630 | ≥22 | ≥31 | ≥27 | ≥24 | ≥20 | ||||||
| 16-40 | ≥345 | |||||||||||||
| 40-60 | ≥335 | 450-610 | ||||||||||||
| S355M | 1.8834 | L | 5-50 | - | - | - | ≥63 | ≥55 | ≥51 | ≥47 | ≥40 | ≥31 | ≥27 | |
| T | 5-16 | ≥355 | 470-630 | ≥22 | ≥40 | ≥34 | ≥30 | ≥27 | ≥23 | ≥20 | ≥16 | |||
| 16-40 | ≥345 | |||||||||||||
| 40-50 | ≥335 | 450-610 | ||||||||||||
Chemical properties:
| EN Standard | Designation | Thickness | C (%) | Mn (%) | P (%) | S (%) | Si (%) | Al (%) | Cu (%) | Cr (%) | Ni (%) | Nb (%) | V (%) | Ti (%) | N (%) | Ceq (%) | Mo (%) | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| EN 10027-1 | EN 10027-2 | (mm) | ||||||||||||||||
| EN 10025-2 | S355JR | 1.0045 | 5-30 | ≤0.24 | ≤1.6 | ≤0.035 | ≤0.035 | ≤0.55 | ≤0.55 | ≤0.012 | ≤0.45 | |||||||
| 30-120 | ≤0.47 | |||||||||||||||||
| S355J0 | 1.0553 | 5-30 | ≤0.20 | ≤1.6 | ≤0.030 | ≤0.030 | ≤0.55 | ≤0.55 | ≤0.012 | ≤0.45 | ||||||||
| 30-120 | ≤0.22 | ≤0.47 | ||||||||||||||||
| S355J2+N | 1.0577 | 5-30 | ≤0.20 | ≤1.6 | ≤0.025 | ≤0.025 | ≤0.55 | ≤0.55 | - | ≤0.45 | ||||||||
| 30-120 | ≤0.22 | ≤0.47 | ||||||||||||||||
| S355J2 | 1.0577 | 5-30 | ≤0.20 | ≤1.6 | ≤0.025 | ≤0.025 | ≤0.55 | ≤0.55 | - | ≤0.45 | ||||||||
| 30-120 | ≤0.22 | ≤0.47 | ||||||||||||||||
| S355K2+N | 1.0596 | 5-30 | ≤0.20 | ≤1.6 | ≤0.025 | ≤0.025 | ≤0.55 | ≤0.55 | - | ≤0.45 | ||||||||
| 30-120 | ≤0.22 | ≤0.47 | ||||||||||||||||
| S255K2 | 1.0596 | 5-30 | ≤0.20 | ≤1.6 | ≤0.025 | ≤0.025 | ≤0.55 | ≤0.55 | - | ≤0.45 | ||||||||
| 30-120 | ≤0.22 | ≤0.47 | ||||||||||||||||
| EN 10025-3 | S355N | 1.0545 | 5-63 | ≤0.20 | 0.90-1.65 | ≤0.030 | ≤0.025 | ≤0.50 | ≥0.020 | ≤0.55 | ≤0.30 | ≤0.50 | ≤0.050 | ≤0.12 | ≤0.050 | ≤0.015 | ≤0.43 | ≤0.10 |
| 63-120 | ≤0.43 | |||||||||||||||||
| S355NL | 1.0546 | 5-63 | ≤0.18 | 0.90-1.65 | ≤0.025 | ≤0.020 | ≤0.50 | ≥0.020 | ≤0.55 | ≤0.30 | ≤0.50 | ≤0.050 | ≤0.12 | ≤0.050 | ≤0.015 | ≤0.43 | ≤0.10 | |
| 63-120 | ≤0.43 | |||||||||||||||||
| EN 10025-4 | S355M | 1.8823 | 5-40 | ≤0.14 | ≤1.60 | ≤0.030 | ≤0.025 | ≤0.50 | ≥0.020 | ≤0.55 | ≤0.30 | ≤0.50 | ≤0.050 | ≤0.10 | ≤0.050 | ≤0.015 | ≤0.39 | ≤0.10 |
| 40-60 | ≤0.40 | |||||||||||||||||
| S355ML | 1.8834 | 5-40 | ≤0.14 | ≤1.60 | ≤0.025 | ≤0.020 | ≤0.50 | ≥0.020 | ≤0.55 | ≤0.30 | ≤0.50 | ≤0.050 | ≤0.10 | ≤0.050 | ≤0.015 | ≤0.39 | ≤0.10 | |
| 40-50 | ≤0.40 | |||||||||||||||||
The S of Steel
The most commonly used steels in construction are S235, S275, S355 and S460. These are thermomechanically rolled steels, where the "S" stands for "Structural steel" and the number indicates the yield strength in MPa. For example, S355 has a yield strength of 355 MPa, which is 50% higher than that of S235. Although the strength varies, the chemical composition of S235 and S355 is nearly identical. The difference is mainly in the rolling and cooling techniques, which affect mechanical properties such as yield strength and tensile strength.
S355 is sometimes considered a high-strength steel because S235 was the standard for a long time. However, this is an incorrect designation. Steel is only considered a high-strength steel from S690 onward, which is mainly used in industries such as crane construction and offshore. These steels obtain their high strength from an increased carbon content, resulting in a different material composition, production methodology and stricter welding requirements. In this article, we will not discuss the other steels further, and focus on the comparison between S235 and S355 or S460.
Figure 1 shows a schematic representation of the stress-strain diagram and mechanical properties of different steel grades. We can see that at higher steel grades, the tensile strength increases while the elongation at break decreases. The stiffness due to the modulus of elasticity remains the same.
S235 as a standard in construction is obsolete
The potential of S355 or S460 is limited by the use of S235 as a standard in construction. Remarkably, the cost and energy consumption per kilogram for steels S235, S275, S355 and S460 are almost the same, while S355 and S460 can offer significantly better performance.
By introducing S355 as a standard, more sustainable constructions can be achieved. This is therefore a logical step, similar to the evolution in rebar. Where previously QR/FeB 220 was used, today FeB 500 is the standard. No one would now use FeB 220 in new concrete structures.
The main advantage of using higher grades of steel is that we can optimize material consumption for the same strength, by slimming profiles and reducing slab thicknesses. Less material consumption means less steel and thus lower economic costs. In addition, this leads not only to cost savings in euros, but also to fewer CO2 emissions, which contributes positively to climate goals, since steel production plays a major role in emissions.
Calculate your advantage - S235 vs S355 in IDEA StatiCa Connection
In the following example, we make a comparison between a connection performed in S235 and S355. In doing so, we examine whether the use of S355 can contribute to material savings.
We analyze a column-girder connection with a head plate, where the connection can be considered semi-rigid (flexible). A stiffness analysis was performed for different situations using IDEA StatiCa to investigate the influence on the moment-rotation diagram, moment resistance and failure mechanism. The original connection is made entirely in S235 and consists of six M16 8.8 bolts, a head plate with a thickness of 10 mm and double corner welds with a thickness of 5 mm for the flanges and 3 mm for the body. The column is an HEA200 section and the beam is an IPE220 section. Figure 2 shows the connection and the results for the different situations.
For each situation, a stiffness analysis was performed with IDEA StatiCa Connection, and the results are superimposed in a moment-rotation diagram in Figure 3. Next, each situation is explained in more detail. We begin with the connection performed in S235 and S355.
S235:
The joint performed in S235 achieves a moment resistance of about Mj,Rd = 45 kNm. The joint exhibits reasonable deformation capacity because the failure mechanism is determined by plastic strain in the body of the column.
S355
For the same joint performed in S355, the initial rotational stiffness remains unchanged (see Figure 3). Since the E-modulus and geometry remain the same, the stiffness does not change. However, the moment resistance of the joint increases, with Mj,Rd for S355 about 30% higher than for S235. Although the strength increases, the deformation capacity decreases as the failure mechanism shifts. At S235, the column body reaches 5% plastic strain, while at S355, the welds on the head plate reach the maximum allowable stress, leading to a less ductile failure mechanism.
To obtain the same moment resistance at S355 as at S235, the joint can be optimized for material savings. This can be achieved by making the head plate thinner, by using smaller bolts, or by reducing the profile cross sections of the column and beam.
S355 smaller bolts
When applying M14 or M12 8.8 bolts instead of M16, Mj,Rd is reduced, but the deformation capacity also decreases significantly as shown in Figure 3. With a reduction in bolt size, you maintain the initial stiffness of the connection, but sacrifice deformation capacity and strength because the failure mechanism shifts to the bolts. Based on this observation and because the amount of material saved is negligible, it is not advantageous to make the bolts lighter. This was to be expected since the bolt quality itself is not increased.
S355 thinner head plate
With a reduction in the thickness of the head plate, you sacrifice strength and stiffness, but retain deformation capacity because the head plate will flow. At a head plate of t = 6 mm, stiffness and moment resistance are significantly reduced. However, at t = 8 mm, approximately the same Mj,Rd is achieved as with S235, but with a reduced plate thickness. This saves material without significant negative impact on joint stiffness and strength.
S355 slimmer profiling
When the head plate thickness remains at 10 mm, but the cross-sections of the column and beam are reduced to a point where Mj,Rd is about 45 kNm, this results in equal moment resistance and reasonable deformation capacity, but with less material usage. In this case, the cross sections are reduced from HEA200 and IPE220 to HEA160 and IPE200, respectively.
What is a S355J2 steel equivalent to?
S355J2 steel, a common European standard structural steel, has equivalents in other countries and industries. In the USA, ASTM A572 Grade 50 is a close equivalent, while DIN St52-3 in Germany is another. Other equivalents include BS 50D in the UK and JIS SM490B in Japan.
What is the equivalent of S235JR steel?
S235JR, a European standard carbon steel, is commonly equivalent to ASTM A36 (American standard) and JIS SS400 (Japanese standard). These are all considered mild steels suitable for various structural applications. Additionally, ISO E235B is another European standard non-alloy structural steel grade that is equivalent to S235JR.
What is the US equivalent of S355?
A572-50
S355 Equivalent Plate Grade
The chemical composition and mechanical properties of S355 are governed by EN Standards However, some projects may require materials that meet ASTM standards. ASTM has identified A572-50 as an acceptable substitution for S355.
What material code is S355JR?
S355 Grade ranges S355JR, S355J0, S355J2, S355K2 which are non-alloy structural steel material specified in EN 10025 standard. "S" means structural, "355" representas yield strength at 355 Mpa minimum.
What is mild steel BS EN 10025 S275JR?
S275 & S275JR steel can be supplied in plate, round bar and flat bar. S275 provides a lower strength (than S355) but has good machinability and can be welded. The average minimum yield for S275 steel is 275 N/mm² giving its name: S275. BS EN 10025 S355, S355JR, S355J2 and S355J2+N supercedes BS4360 50A, 50B, 50C 50D.
What is the steel equivalent of S235?
AI Overview
S235 steel has several equivalents in different standards, including ASTM A36, A283C, and Q235B, which are used in the US and China respectively. The specific equivalent depends on the standard being used (e.g., ASTM, JIS, DIN), but they all share similar chemical and mechanical properties, making them suitable for structural applications.
Equivalents by standard
ASTM (US): A36 and A283C are considered equivalents.
JIS (Japan): SS400 is the equivalent.
DIN (Germany): ST37-2 and ST37-3N are the equivalents.
GB/T (China): Q235B is the equivalent.
EN (Europe): The specific grades within the S235 family are S235JR, S235J0, S235J2, and S235K2. The base S235 grade corresponds to S235JR, according to EN 10025-2.
Key takeaways
A36: Often considered the most direct equivalent for general construction in the USA.
A283C: Another US standard equivalent, also used for structural purposes.
Q235B: China's equivalent, which requires a careful evaluation of subtle differences in composition and performance before substitution.
SS400: A general structural steel used in Asia for applications like beams and brackets.
ST37-2: The older DIN standard equivalent to S235JR.
What is the Chinese equivalent of S235?
Q235B
The closest Chinese equivalent to S235JR (EN 10025-2) is Q235B (GB/T 700-2006). While these grades share similar mechanical properties, subtle differences in composition and performance must be carefully evaluated for compliance and safety.
What is the yield strength of S235 steel?
Grade S235JR has a minimum yield strength of 235 MPa. The impact energy at a room temperature of 20°C is at least 27 joules. Steels of grade S235JR are suitable for low-stressed parts in steel and mechanical engineering.
Does S355 steel rust?
S355 steel is easy to be corroded between 30 and 35 °C. The critical humidity of the S355 steel corrosion is 75%. The moisture condensing and illumination realizes dynamic balance at 70 W/m2, suggesting a lowest corrosion rate.
What is the difference between ASTM A36 and s235?
ASTM A36 has stricter limits on carbon content (≤0.26%), ensuring consistent quality. S235JR has tighter controls on phosphorus and sulfur, enhancing weldability.
The main difference is that ASTM A36 is an American Society for Testing and Materials (ASTM) standard while S235 is a European standard, leading to variations in their chemical and mechanical properties, such as A36 having a minimum yield strength of 250 MPa and S235JR having a minimum of 235 MPa. Additionally, S235JR has more stringent limits on phosphorus and sulfur and requires impact testing, which A36 does not.
What is ASTM A36 equivalent to?
ASTM A36 has several equivalents in different international standards, including S235JR (European), SS400 (Japanese), Q235B (Chinese), and St 37-2 (German). Other equivalents include 260W (Canadian), E250 (Indian), and E 235 (ISO). When selecting an equivalent, it's important to consider regional availability and specific mechanical and chemical properties.
Is S355 hot rolled?
S355 is a low carbon, hot rolled structural steel, extensively used in the production of hot rolled universal beam, column and other long products. Chemical and mechanical levels are ideal for machining and forming.
