Carbon structural steels-(ISO 630:1995,Structural steels Plates,wide flats,bars,sections and profiles)
GB/T 700-2006 is applicable to carbon structural steel products for general use in the as-delivered condition (without special heat treatment), including plates, profiles, bars, etc.
Product Forms
Plates: Steel plates and strips of various thicknesses.
Profiles: Structural steel sections (e.g., I-beams, channels, angles) for building frameworks.
Bars: Steel bars in various cross-sectional shapes (e.g., round, square).
Usage Conditions
Primarily used at ambient temperatures.
Designed to bear static loads.
No special requirements for corrosion resistance or high-temperature performance.
Typically assembled into structures via welding, riveting, or bolting.
Example Application
The main structural framework of a 30-story residential building in Beijing uses H-shaped steel columns and I-beam girders made of Q235B steel (per GB/T 700-2006), representing a classic application of this standard.
Steel Grade Nomenclature in GB/T 700-2006
The standard employs a clear and intuitive naming system for steel grades. For example, "Q235B" is decoded as follows:
"Q": Represents the Chinese pinyin initial of "Qu" (yield), indicating yield strength.
"235": Denotes the standard yield strength value, in MPa (or N/mm²).
"B": Indicates the quality grade, with levels A to D in ascending order of quality.
Optional suffixes:
"F" (boiling steel) or "Z" (killed steel, often omitted).
For further details on chemical composition and mechanical properties, refer to the standard's classification of quality grades (A-D) and deoxidation methods (F/Z/TZ).
ere we show the difference between Q195, Q215, Q235 & Q275 steel, these series steel all belong to Chinese standard carbon structural steel, the lising below shows the difference of chemical composition and mechanical properties.
Chinese Standard Carbon Structural Steel Specification
| Chemical Composition | ||||||
| Steel Series | Steel Grade | C % (≤) | Si % (≤) | Mn (≤) | P (≤) | S (≤) |
| Q195 | Q195 | 0.12 | 0.3 | 0.5 | 0.035 | 0.04 |
| Q215 Series | Q215A | 0.15 | 0.35 | 1.2 | 0.045 | 0.05 |
| Q215B | 0.15 | 0.35 | 1.2 | 0.045 | 0.045 | |
| Q235 Series | Q235A | 0.22 | 0.35 | 1.4 | 0.045 | 0.05 |
| Q235B | 0.2 | 0.35 | 1.4 | 0.045 | 0.045 | |
| Q235C | 0.17 | 0.35 | 1.4 | 0.04 | 0.04 | |
| Q235D | 0.17 | 0.35 | 1.4 | 0.035 | 0.035 | |
| Q275 Series | Q275A | 0.24 | 0.35 | 1.5 | 0.045 | 0.05 |
| Q275B | 0.21 | 0.35 | 1.5 | 0.045 | 0.045 | |
| Q275C | 0.2 | 0.35 | 1.5 | 0.04 | 0.04 | |
| Q275D | 0.2 | 0.35 | 1.5 | 0.035 | 0.035 | |
| Mechanical Properties (N/mm2 = Mpa) | ||
| Grade | Yield Strength | Tensile Strength |
| Q195 | 195 | 315-430 |
| Q215 | 215 | 335-450 |
| Q235 | 235 | 370-500 |
| Q275 | 275 | 410-540 |
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Standard Equivalent |
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China |
America |
Japan |
Germany |
England |
France |
ISO |
Korea |
India |
|
Q195 |
Grade B |
SS330 |
S185(1.0035) |
E185 |
D |
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Q215 |
Grade C |
SS330 |
Fe-330 |
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Q235-A |
Grade D |
SS400 |
S235JR (1.0038) |
E235 A |
SS400 |
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Q235-B |
S235J0(1.0114) |
Fe-410 |
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Q235-C |
S235J2(1.0117) |
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Q235-D |
S235JR(1.0038) |
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Q275 |
SS Grade |
SS490 |
S275JR(1.0044) |
E275 |
SS490 |
Fe-490 |
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Q345-A |
Grade |
SPFC590 |
E355(1.0060) |
E355 |
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|
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Q345-B |
S355JR(1.0045) |
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Q345-C |
S355J0(1.0553) |
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Q345-D |
S355J2(1.0577) |
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Q345-E |
S355NL(1.0546) |
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What is the difference between Q275 plate and Q235 plate?
First, The yield limit is different: the yield limit of Q235 plate is 235MPa; the yield limit of Q275 plate is 275MPa. All of them are ordinary carbon structural steel, Q represents the yield limit of the steel material, and the following numbers refer to the yield value of the steel material.
Second, Carbon content and tensile strength are different: Q235 plate carbon content is 0.14-0.22%, tensile strength is 375-500; Q275 plate carbon content is less than 0.37%, tensile strength is 410-560. The carbon content of Q275 plate is generally higher than that of Q235 plate, and the tensile strength is also higher.
Third, Different applicability: Q235 plate is applied to buildings and engineering structures, such as making steel bars or building workshop frames, high-voltage transmission towers, vehicles, boilers, containers, ships, etc. Q275 plate is used to manufacture parts with high strength requirements, such as gears, shafts, sprockets, nuts, profile steel for agricultural machinery, conveyor chains and chain links.
What is the main difference between Q235 steel and S355 steel?
Q235 steel is a normal carbon structural steel, while S355 steel is a low alloy high strength structural steel, the tensile strength of Q235 steel is 235 Mpa, while the tensile strength of S355 steel is not less than 355Mpa. S355 steel has higher strength and hardness than Q235 steel, with good weldability and impact toughness.
What is the chemical components difference between Q235 steel and S355 steel?
The mainly chemical components of Q235 steel include C, Si, Mn, S, P and other elements, in addition to these elements, S355 steel may include other alloying elements such as V, Ti, Nb etc. These elements can improve the strength and the toughness of the steel.
Comparison of mechanical properties of Q235 steel and S355 steel?
The mechanical properties of S355 steel are usually better than Q235 steel, including higher yield strength , tensile strength and impact toughness. S355 steel can remain good impact property under low temperature condition, it make S355 steel suitable for strict application scenario.
What does Q235 steel and S355 steel perform in terms of corrosion resistance?
S355 steel generally has better corrosion resistance than Q235 steel because it has more alloy elements. In some specific marine engineering applications, S355 steel may be a better choice, or Q235 steel could be given a special surface treatment to improve its corrosion resistance.
