Pickling process and quality control

Stainless steel pickling steel, strip steel surface state, annealing conditions factors, the process is not the same, shall be determined according to the specific situation.  Acid concentration control ( 硝酸+高频) In mixed acid pickling reaction is more complex, according to the general law of the concentration of reactive balance of practical experience and many manufacturers, mixed acid concentrations of acid tank, HNO3 usually control - in 80 160 g/l, HF in 8 - control Between 30 g/l. It should be pointed out is HF concentration can not too high, otherwise the metal loss increase, and make the rough surface. Most manufacturers use sulfur acid trough, nitric acid electrolytic cell and ( 硝酸+高频) Mixed acid tank combined pickling process, including the concentration of sulfur acid tank control in 150 - 200 g/l.  Acid temperature control can improve the effect of temperature as well as improving concentration can increase pickling, when the concentration of metal ions is more than 45 g/l, improve the effect of temperature in pickling more obvious than improve concentration, so the use of low concentration, high temperature more pickling process. Acid of the higher the temperature, the faster reaction rate, the better the pickling, but at high temperature, acid evaporation ( Especially the HF acid) , consider the degree of heat resistance of pickling bath at the same time, not too high, so the temperature control in the 50 - usually 60℃。 Acid temperature automatic control, usually to prevent abnormal instrument, need to check on a regular basis.  Fe ion concentration control when pickling acid and base metal of Fe, Cr and other alloying elements react to generate metal salts ( Mainly Fe) , and USES the wet analysis to calculate the concentration of acid, including the metal ion of acid salt. This analysis of acid concentration, even if the same, because of the metal ion in the acid ( Iron ions) Different concentration of free acid points is different. Namely along with the increase of the concentration of iron from the free acid content is reduced, pickling effect, in addition, the high concentration of metal ions in the solution, can form difficult soluble fluoride is easy to jam pumps and piping. Therefore, to manage of Fe ion concentration, lest cause acid pickling or bad, in the mixed acid trough the concentration of iron ions in general should be controlled under present 45 g/l. To solve this problem, use the AT - AT present 50 rapid analysis device, analysis of free acid in the acid by electrochemical process. 在- - - - - - 50 is the basic working principle of quick analysis device by ion selective electrode, directly measured H +, F - in the solution Amount to calculate the corresponding acid concentration. Above all, is the core issue of management of acid pickling process, in addition to in the process of on board frequently check, prevent the formation of defects is also very important. Refund acid pickling equipment length is about the unit length of more than half, often make the strip surface defect on board process, and it is covered, the discovery of defects often late, so we must strengthen the tally, establish quality guarantee system.