What Is Q345 Round Steel?

Q345 is a low alloy high strength structural steel, which has good comprehensive mechanical properties and good low temperature performance. It can be used in oil tanks, vehicles, cranes, mining machinery, power stations and bridges and other structures bearing dynamic loads in cold regions.

It contains small amounts of Ti, Nb and V trace alloying elements. It has welding property, but it is sensitive to cold cracks after welding, and requires strict process measures.

Strength

Q345 steel is a low alloy structural steel. It is widely used in construction, bridges, vehicles, ships, and pressure vessels. Its yield strength is about 345 MPa and will decrease with the increase in material thickness.

The proportion of the main elements in Q345 is essentially the same as that of 16Mn steel, and V, Ti, and Nb microalloy elements are added to refine the grains, improve the toughness, and enhance its comprehensive mechanical properties. Its low temperature performance is also better than that of 16Mn steel.

Due to its good low temperature performance, plasticity, and weldability, this steel is commonly used in low pressure vessel, oil tank, vehicles, cranes, mining machinery, power stations, etc. It is often rolled into plate or bars to make parts for these structures.

However, the welding property of Q345 steel is not good and it easily forms cracks in the heat affected zone after welding. Hence, strict process measures should be taken during welding. In addition, pitting corrosion in Q345 steel is a common problem and it can significantly reduce the nominal tensile strength of the steel component. Therefore, a method to predict the residual tensile strength of steel components after pitting corrosion was developed based on its microscopic fracture morphology. The results showed that the predictive model could provide a useful tool to assess the residual tensile strength of steel component after pitting corrosion.

Weldability

Q345 steel is a low alloy structural steel with good weldability and low temperature performance. It is commonly used in Q345 round steel building structure, mechanical parts, cranes, vehicles, ships, power stations, and other structures that are exposed to cold environments or high loads. This steel has similar characteristics to Q235 steel, but is stronger and more resistant to fatigue damage.

This type of steel is also known as HSLA (high strength low alloy) and is often used in construction projects that require extra durability, such as bridges and buildings. It can withstand higher stress and heavier loads than other types of structural steel. This steel is not as cost-effective as Q235, but it is an ideal choice for applications where safety and longevity are important factors.

Welding Q345 steel is more difficult than other grades of steel because it has a tendency to cold crack after welding. The welding process must be carefully controlled to avoid this problem. The best way to avoid this is to use low-hydrogen type welding materials and a manual arc welding method.

The tensile properties of Q345 steel are affected by the type of loading condition, but the change in these properties is mainly determined by the microscopic fracture morphology. In this study, the ductile fracture of the base metal and heat-affected zone (HAZ) material of Q345 steel was studied using an optical measurement method. The actual fracture strains were measured and the failure criterion parameters fitting the J-C fracture model were obtained.

Chemical Composition

Q345 steel is a low alloy structural steel, which conforms to the standard of GB/T 1591-2008. It has a higher yield strength than other types of steel, which makes it well-suited for construction projects. It can withstand heavy loads and provide structural stability. It also has excellent weldability and machinability, making it easy to work with.

In order to improve its comprehensive mechanical properties, this steel is added with a small amount of V, Ti and Nb microalloy elements. These elements are used to refine the grain structure of the steel and enhance its toughness. They can also improve its low temperature performance and plasticity.

The chemical composition of this steel varies slightly depending on the specific grade. It can be divided into grades Q345A, Q345B, Q345C, Q345D, and Q345E according to its impact resistance, which differs from one another mainly by their impact temperatures.

This steel is widely used in the construction industry because of its high strength and durability. It is especially useful in places that need to withstand extreme stress or pressure, such as bridges and other structural components. It is also used in shipbuilding applications, including constructing hulls and decks. Finally, it is also used in the energy industry to construct pipelines and storage tanks. This steel is also resistant to corrosion, which makes it a great choice for marine environments.

Applications

Q345 is a low alloy steel (C0.2%), commonly used in bridges, vehicles, ships, buildings and pressure vessels. Its name is derived from its yield strength Q195 carbon steel angle steel which is approximately 345MPa. However, its actual yield value is much higher than this number. It is important to note that because of this difference, the allowable stress for different thicknesses of this material should be re-determined.

Its good mechanical properties, low temperature performance and excellent weldability make it ideal for use in low-pressure tanks, vehicle bodies, cranes, mining machinery and general metal parts. It can also be used for other structures that are exposed to cold environments and high loads.

The tensile strength of a material is the amount of bending or stretching that it can take before failure, such as breaking. It is measured in units of force divided by cross sectional area, the SI unit for this measurement being the Pascal, where one Pascal equals a Newton per square meter. The tensile strength of Q345B is rated at between 470 and 630 Mega Pascals.

The Brinell scale measures the hardness of materials through an indentation test on a sample surface. This method of testing is particularly suitable for measuring the surface hardness of metals, since it does not damage the specimen. It is also the preferred test for testing the hardness of welds.