Static Performance of 2nd Grade Steel

• Guide
• CHY Engineering Team

Using prime quality sheet metal for every fixture-based project in production lines and heavy industry is not always financially sustainable. Using secondary grade steel in the production of carcasses, chassis supports, or concealed structural beams where tonnage reaches critical dimensions is a completely feasible maneuver from an engineering standpoint. However, at this point, it is necessary to analyze whether the material's metallurgical defect is only surface (cosmetic) or structural.

Yield Strength and Tensile Test Data

Whether a secondary grade material can be used in a structural system is determined by looking at the yield strength. When traditional hot rolled steel (S235 or S275 series) products are subjected to standard tension tests, the point where plastic deformation begins is clearly defined. In secondary grade steel, there may be scale pits or thickness deviations at the ends or in the center of the material. In calculating the Bending Moment, the section modulus (W) at the thinnest cross-section of the sheet must be taken as the reference.

When a standard 3.00 mm nominal thickness HRP coil is passed through the cut-to-length line, the center of the material might measure 2.98 mm, and the edges 2.85 mm (Edge drop effect). If a profile is to be bent, the static calculation must be made based on this 2.85 mm, where the mechanical strength is weakest.

Stress Relief (Leveling) in Cut-to-Length Lines

Residual stress, which is frequently encountered in secondary grade coils, can only be eliminated in advanced multi-roll leveling units. It is not enough to just flatten the sheet; it is also imperative to erase the coil set in the material's memory. Otherwise, when you lay the sheet on the laser cutting table, it bows upward and crashes into the laser head, damaging your machine.

Products that are accurately analyzed, have tolerable scale rates, and are dimensioned to meet the static load are the secret to profitability in the construction and machinery sectors.