Q420ND is a low-alloy structural steel with excellent mechanical properties and weldability, suitable for applications in building structures, bridges, ships, vehicles, machinery manufacturing, and other fields. The normalizing rolling process for Q420ND is as follows:

1. Steelmaking: Q420ND steel plates are produced using the electric furnace steelmaking method, undergoing processes such as deoxidation, desulfurization, and dephosphorization to ensure the quality of the molten steel.

2. Refining: The molten steel is treated with VD (Vacuum Degassing) to further remove gases and impurities, improving the purity of the steel.

3. Continuous Casting: The refined molten steel undergoes continuous casting to form billets. The billets have a smooth surface and good dimensional accuracy, providing high-quality raw material for subsequent rolling.

4. Hot Rolling: The billets are hot-rolled through multiple rolling processes, gradually reducing the thickness and increasing the length to form hot-rolled steel plates. During hot rolling, the normalizing rolling of Q420ND is achieved by controlling the rolling temperature and degree of deformation.

5. Stacking: The hot-rolled steel plates are stacked and naturally cooled to room temperature. During stacking, internal stresses are gradually released, and the grain structure is refined, resulting in a normalized microstructure.

6. Surface Inspection: The cooled steel plates undergo surface inspection to remove surface defects and flawed sections.

7. Batch Testing: The steel plates are subjected to batch non-destructive testing to check for internal defects such as pores, slag inclusions, and cracks.

8. Performance Testing: The steel plates undergo performance tests, including tensile tests and impact tests, to ensure they meet the mechanical property requirements of Q420ND.

9. Cutting: Based on customer requirements, the steel plates are cut into the desired dimensions and shapes.

10. Warehousing: The cut steel plates are marked, classified, and stored in the warehouse, awaiting shipment.

Through the above normalizing rolling process for Q420ND, a low-alloy structural steel with excellent mechanical properties, weldability, and weather resistance can be obtained.