Steel Plate Pickling Defination
The full name of the pickled sheet roll is "hot rolled pickled steel plate or sheet", which usually refers to the product obtained by removing the hot rolled surface iron oxide scale with hydrochloric acid (HCl).Hot rolled pickled steel sheet or coil can be further processed into cold rolled steel products. The acid-washed substrate is directly in contact with the environment, and unlike the surface of the cold-rolled annealed sheet, the dense oxide layer usually has a certain protective effect, so the surface of the pickled product is very prone to oxidized yellow spot defects.
Basic Rules of Pickling Process for Various Steel Standards
In view of this characteristic of pickled products, there are specific descriptions and reminders in each of the major standards. Taking Baosteel's enterprise standard Q/BQB 302 as an example, the description is as follows (the focus is marked in red): The steel plate and steel strip on the pickled surface can be delivered with or without oil. After oiling the pickled steel sheet and steel strip, under normal packaging, transportation, handling and storage conditions, the supplier shall ensure that no corrosion occurs within 3 months from the date of completion of production, and the oil film to be coated shall be removed with an aqueous alkali solution. If the supplier requests to supply the oil-free pickled steel plate and steel strip, it should be stated in the contract. Acid-washed steel plates and steel strips that are not oiled are prone to rust and abrasion during transportation and processing, and the supplier does not guarantee this. This is similarly described and suggested in each of the hot rolling steel plate standards.
The Cause of Macula on the Surface of Pickled Steel Sheet
Steel mill production, packaging, storage, transportation, and one-time processing are all possible. Therefore, in the analysis of yellow spot defects, it is necessary to mobilize the information of each link for comprehensive analysis in order to obtain an accurate judgment. Many technicians like to analyze the elemental composition of the macula and determine whether there is Cl residue.
It must be said that this method is simple and rude, and there are quantitative data that is easily accepted by users. However, if the surface features of the macula are neglected, it is easy to ignore the real cause, resulting in a passive situation in the subsequent processing of the abnormal material.
Basic Routines for Quality Defect Analysis
Quality defect analysis and criminal investigation have many things in common. They are essentially a kind of work to trace back beforehand and find out the cause by the result. The reasoning model is retrospective. The method is to continuously approach the hypothesis verification exclusion method of the target. Therefore, to understand the background information of the defective steel plate products, collect and classify the regularity and shape of the defects, and then combine the empirical analysis to form a complete evidence chain, and confirm that this is the basic routine of quality defect analysis. AGICO supplies Hot Rolled Pickled Steel Sheet product following strict manufacture process, if you are interested, please contact agico now for more steel grades info and latest price!
