The Z to steel plate produced by our company is marked with Z to steel plate mark at the back of the female steel number. In the process of rolling, with the increase of the thickness of the steel plate, the compression ratio of the thickness direction decreases, the mechanical properties of the steel plate in the three directions are different: along the rolling direction performance is good, perpendicular to the rolling direction performance is a little worse, along the thickness direction performance is second. If it is rolled with ordinary steel, especially thick steel, local delamination is often difficult to avoid.
The delamination of steel plate is mainly due to the defects of sulfur, phosphorus segregation and non-metallic inclusion in steel, which will affect the mechanical properties of steel. Sulfur and phosphorus content will directly affect the performance of steel plate thickness direction. Sulfur, phosphorus is the main impurities in the construction of steel, sulfur can produce iron sulfide easy to melt, when the temperature of hot processing or welding reaches 800-1200 degrees Celsius, there may be hot cracks, iron sulfide can form inclusions, not only promote the steel layer, but also cause stress concentration, reduce the plastic and impact toughness of steel. Sulfur is one of the impurities with serious segregation in steel. The higher the segregation degree is, the worse the performance of thickness direction is. Phosphorus is dissolved in ferrite in the form of solid solution, which is very brittle, and the segregation of phosphorus is more serious than that of sulfur. The formation of phosphor-rich zone makes steel brittle and reduces the plasticity, toughness and weldability of steel. Therefore, the Z performance of steel plate to sulfur, phosphorus content should be qualified to ensure, the sulfur content is strictly controlled. Steel ingot after hot rolling, the formation of steel ingot bubble, crack and loose defects, can be welded under high temperature and pressure, and refine the steel grain to make the organization compact, mechanical properties are improved.
