Introduction to Q345B Q355B grade of low-alloy square tube.
Low-alloy square tube is one of the commonly used structural materials in construction engineering, with good mechanical properties and process properties, and is widely used in construction, machinery, petroleum, chemical industry, electric power, transportation and other fields. Among them, Q345B and Q355B are the most commonly used grades in low-alloy square tubes, and the introduction of these two grades will be introduced in detail below.
1. Introduction to Q345B grade.
Q345B is a low-alloy high-strength structural steel with good strength, toughness, corrosion resistance and cold working performance, which is widely used in construction, bridges, ships, vehicles, pressure vessels and other fields.
1.Chemical composition.
The chemical composition of Q345B is as follows:
Carbon(c): 020%
Silicon (Si): 050%
Manganese (mn): 100%-1.60%
Sulfur (s): 0035%
Phosphorus (p): 0035%
Chromium (cr): 030%
Nickel (Ni): 030%
Copper (cu): 020%
Titanium(Ti): 020%
Molybdenum (Mo): 020%
2.Mechanical properties.
The mechanical properties of Q345B are as follows:
Tensile strength (b): 390MPa
Yield strength (s): 295MPa
Elongation (δ) 11%.
Impact toughness ( ku): 27j cm2
3.Precautions for use.
When using the Q345B, you need to pay attention to the following:
1) Q345B has good welding performance and can be welded by various welding methods, such as electrode arc welding, gas shielded welding, submerged arc welding, etc. In the welding process, the appropriate welding process parameters should be selected according to the actual situation, and the corresponding preheating and post-heat treatment should be carried out.
2) When Q345B is used in a low temperature environment, the corresponding low temperature impact toughness test should be carried out to ensure that it has sufficient low temperature toughness.
3) When Q345B is used at higher temperatures, the corresponding high-temperature mechanical properties test should be carried out to ensure that it has sufficient high-temperature resistance.
2. Introduction to Q355B grade.
Q355B is a low-alloy high-strength structural steel with good strength, toughness, corrosion resistance and cold working properties, which is widely used in construction, bridges, ships, vehicles, pressure vessels and other fields. Compared with Q345B, Q355B has a slightly higher yield strength and better low-temperature toughness.
1.Chemical composition.
The chemical composition of Q355B is as follows:
Carbon(c): 024%
Silicon (Si): 050%
Manganese (mn): 100%-1.60%
Sulfur (s): 0035%
Phosphorus (p): 0035%
Chromium (cr): 030%
Nickel (Ni): 030%
Copper (cu): 020%
Titanium(Ti): 020%
Molybdenum (Mo): 020%
2.Mechanical properties.
The mechanical properties of Q355B are as follows:
Tensile strength (b): 490MPa
Yield Strength (s): 345MPa
Elongation (δ) 18%.
Impact toughness ( ku): 27j cm2