Q345qD steel plate new standard impact value indicators and application fields

Q345qD steel plate is a low-alloy high-strength structural steel suitable for manufacturing structural components that bear significant loads. "Q" stands for yield strength, "345" indicates its minimum yield strength of 345 MPa, and "qD" signifies that the material has specific impact absorption energy requirements at -20°C, along with good weldability and low-temperature toughness.

New Standard Impact Value Indicators

1. Impact Absorption Energy: According to the Chinese national standard GB/T 1591-2018, Q345qD steel plate must have an impact absorption energy of at least 34J (Charpy V-notch impact test) under low-temperature conditions of -20°C.

2. Impact Test Temperature: The impact test for Q345qD steel plate is conducted at -20°C to ensure the material's toughness in low-temperature environments.

3. Sample Size: Impact test samples typically adhere to standard size requirements to ensure consistency and comparability of test results.

4. Chemical Composition: The chemical composition of Q345qD steel plate is designed to enhance its low-temperature impact performance, including appropriate alloying elements such as manganese (Mn), silicon (Si), vanadium (V), niobium (Nb), and titanium (Ti).

5. Microstructure: Through controlled rolling and heat treatment processes, Q345qD steel plate develops a fine grain and uniform microstructure, which contributes to improved impact toughness.

6. Quality Control: Strict quality control measures are implemented during the production of Q345qD steel plate, including chemical composition analysis, mechanical property testing, and impact tests, to ensure compliance with standard requirements.

Application Areas

Due to its excellent low-temperature impact performance, Q345qD steel plate is suitable for:

1. Cold Region Construction: Building structures in low-temperature environments, such as high-rise buildings and bridges.

2. Engineering Machinery: Engineering machinery operating in cold environments, such as excavators and cranes.

3. Ships and Marine Structures: Ships and offshore platform structures used in cold sea areas.

4. Pressure Vessels: Liquefied gas storage containers and other pressure vessels operating under low-temperature conditions.

5. Energy Industry: Facilities such as liquefied natural gas (LNG) processing plants and transportation pipelines.

6. National Defense: Equipment and facilities used in extreme climatic conditions.

Summary

The impact value indicators of Q345qD steel plate ensure its reliability and safety in low-temperature environments, making it suitable for various applications requiring high strength and good low-temperature toughness. Through precise chemical composition control and heat treatment processes, Q345qD steel plate maintains its performance in low-temperature environments.