Q390D is a high-strength low-alloy structural steel produced according to the Chinese national standard GB/T 1591-2018. It is widely used in applications requiring heavy load-bearing and high-pressure resistance, such as building structures, engineering machinery, shipbuilding, and bridge construction. Q390D steel plates are favored for their excellent weldability, hot and cold workability, and impact toughness.

Regarding the specifications of Q390D coil and medium plates, the thinnest and thickest specifications are typically as follows:

1. Q390D Coil: Coil generally refers to steel plates supplied in rolls after hot rolling. The thickness range of Q390D coil can start from thinner specifications, such as 1.5mm or 2mm, up to thicker specifications like 20mm or more. The width of the coil is generally broad, with common width ranges between 1000mm and 2000mm, while the length can be customized according to customer requirements.

2. Q390D Medium Plate: Medium plates refer to flat steel with larger thickness and width. The thickness of Q390D medium plates typically starts from 6mm or 8mm and can go up to 100mm or even thicker, depending on the production facility's capabilities and product specifications. The width and length of medium plates also cover a wide range, with widths varying from 1500mm to 4000mm and lengths typically between 6000mm and 18000mm.

When selecting Q390D coil and medium plates, users need to choose the appropriate specifications based on their actual application requirements and processing conditions. For example, thinner coil plates are suitable for components requiring bending or forming processes, while thicker medium plates are ideal for structural parts bearing heavy loads. Additionally, steel plates of different thicknesses may require different heat treatment processes to ensure the desired mechanical properties are achieved.

When purchasing Q390D coil and medium plates, it is advisable to consult professional steel suppliers for specific product specifications and supply capabilities to ensure the selected materials meet engineering requirements and safety standards. At the same time, considering material costs and processing difficulties, rational selection of specifications is also an important aspect of controlling project costs.