Q235 Steel Definition
Q represents the yield limit of this material, and the latter 235 refers to the yield value of this material, which is around 235MPa. And will decrease its yield value as the thickness of the material increases.
Equivalent
American Standard A36
European standard S275
Chinese standard A3
Japanese standard SS400
Features of Q235 Steel
Q235 has good plasticity and welding properties, and good forming ability.
Moderate carbon content, good overall performance. Its plasticity and toughness are good, and its welding performance is excellent.
During welding, special process measures such as preheating and post-welding heat treatment are generally not required
And has a certain strength, suitable for use in construction and engineering structures.
It has good practical performance, relatively cheap price, and high-cost performance.
Specification
Chemical composition
Q235 is divided into four levels: A, B, C, D
| Chemical Composition | |||||
|---|---|---|---|---|---|
| Grade | C | Mn | Si | S | P |
| Q235A | ≤0.22% | ≤1.4% | ≤0.35% | ≤0.050 | ≤0.045 |
| Q235B | ≤0.20% | ≤1.4% | ≤0.35% | ≤0.045 | ≤0.045 |
| Q235C | ≤0.17% | ≤1.4% | ≤0.35% | ≤0.040 | ≤0.040 |
| Q235D | ≤0.17% | ≤1.4% | ≤0.35% | ≤0.035 | ≤0.035 |
Mechanical Properties
| Mechanical Properties | |||
|---|---|---|---|
| Grade | Yield Strength | Tensile Strength | Elongation % |
| Q235 Steel | 235 Mpa | 370-500 Mpa | 26 |
Q235AQ235B belongs to ordinary low-carbon steel, and Q235C/Q235D belongs to high-quality low-carbon steel.
- Q235A level is not required for impact toughness test,
- Q235B grade is used for impact toughness test at room temperature (20°℃).
- Q235C grade is for 0°℃ impact toughness test,
- Q235D grade is used for the -20℃ impact toughness test.
The impact toughness test uses Charpy ∨-shaped notched specimens. The impact toughness index is AKV.
For the above-mentioned grades B, C, and D steels, they are required to reach AKV≥27J under their respective temperature requirements. Therefore, the four ranks are ranked as A<B<C<D, and Q235D is the best.
Application
Because q235 has good welding performance, good plasticity, toughness, and certain strength, it is often rolled into thin plates, steel bars, welded steel pipes, etc., used in bridges, buildings, and other structures and the manufacture of ordinary screws, nuts, and other parts. And Q235 C and Q235 D grade steel can also be used as some professional steel.
Q235 vs SS400 vs A36
Chinese standard Q235, the tensile strength is 370~500 MPa, and the yield strength is 235MPa.
Japanese standard SS400, the tensile strength is 400~510 MPa, and the yield strength is 245Mpa.
American Standard A36, the tensile strength is 58~80 Ksi (about 400~550MPa), and the yield strength is 36 Ksi (about 250MPa).
Because the mechanical properties of these three grades are similar, they can be replaced within a certain range.
Heat Treatment
235 belongs to low-carbon structural steel with a carbon content of about 0.12%-0.2%, which is equivalent to ordinary 10 and 20 steel. The hardness does not change much after quenching.
Q235 is generally bought without heat treatment. Generally, it is used in places where a large amount of steel is needed in engineering. The quantity is huge. Generally, it is used after hot rolling. Hot rolling is also a heat treatment of normalizing.
There are several reasons for not heat treatment,
1 These occasions do not require too high mechanical requirements.
2 The volume of these steel components is too large, and the heat treatment is difficult.
3 These steels are often used for welding. After heat treatment, the heat treatment of the weld will be destroyed during the welding process.
4. The material is cheap, the quality requirement is relatively low, and it is low-carbon steel, and the heat treatment effect is not good.
5 If you have to use Q235 to quench the hardness, you can only carburize, and the cost is too high.
What are the different grades of steel?
1. Classified by quality
Ordinary steel (P≤0.045%, S≤0.050%), high-quality steel (P and S ≤0.035%), and high-grade high-quality steel (P≤0.035%, S≤0.030%).
2. Classified by chemical composition
Carbon steel:
Low-carbon steel (C≤0.25%). Medium-carbon steel (0.25≤C≤0.60%) and high-carbon steel (C≥0.60%).
Alloy steel:
low alloy steel (total content of alloying elements ≤5%), medium alloy steel (total content of alloying elements>5~10%), high-alloy steel (total content of alloying elements>10%).
3. Classified by forming method:
Forged steel, cast steel, hot-rolled steel, cold-rolled steel.
How can you tell if steel is high carbon?
The difference between low carbon steel and high carbon steel lies in carbon content and hardness. High carbon steel is often called tool steel, with carbon content ranging from 0.60% to 1.70%, which can be quenched and tempered.
Low-carbon steel is carbon steel with a carbon content of less than 0.25%. Because of its low strength, low hardness, and softness, it is also called mild steel.
The simplest and most direct way to determine the carbon content of carbon steel is to grind sparks on the grinding wheel.
The difference between sparks: low-carbon steel sparks are linear and rarely branched; medium-carbon steel sparks have more points. Forks; high-carbon steel sparks branch a lot; there are also differences in brightness, the higher the carbon content, the brighter.
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Conclusion
Q235 is the most common type of steel in life. This article specifically introduces the knowledge of Q235’s specifications, characteristics, and applications. Hope it can help you.
