Study on the effect of element enrichment on the surface of high-strength pickling steel on the film-forming performance of phosphating film

Abstract

A salt spray test was used to evaluate the corrosion resistance of pickling high-strength steel JSH440W to phosphating film on its surface, and scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to analyze the micro-morphology and element content of the surface defects area of the sample after salt spray test. The results show that the enrichment of Si, Mn, and O elements on the surface of pickling high-strength steel JSH440W badly influences the film-forming performance of phosphating film. The enrichment of Si, Mn, and O elements on the strip steel surface will slow down the film-forming speed of the phosphating film and make the thickness of the phosphating film thinner, which will lead to the reduction of corrosion resistance in this area, and it is easy to cause pitting corrosion behavior, to cause the paint film on the sample surface to fall off. Reducing the enrichment of Si, Mn, and O elements on the surface of acid-washed high-strength steel and increasing the roughness uniformity of strip steel is beneficial to improving the quality of phosphating film and the coating property of pickling high-strength steel.