Analysis and control of yellowing defects causes on 16MnCr5 steel surface
The yellowing defects on the surface of 16MnCr5 steel plates negatively impact surface quality.The causes of these yellowing defects was using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and glow discharge spectroscopy(GDS).The findings reveal that the defects are closely linked to the oxidized iron scale on the surface of hot-rolled steel plates and the control of acid washing process.With Mn and Cr mass fraction reaching up to 2％,these elements diffuse along the grain boundaries during high-temperature coiling,forming in-tergranular oxidation products.This leads to preferential corrosion of the grain boundaries and pore formation during acid washing,which traps the acid solution and results in surface oxidation and yellowing.Inadequate rinsing exac-erbates the severity of the yellowing.To address these issues,strategies such as reducing the hot rolling coil tem-perature,increasing the cooling rate after coiling,and improving the rinsing process were proposed.Following these adjustments,the yellowing defect is significantly reduced,effectively controlling a typical genetic defect in hot roll-ing.
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