Experimental Study on Sulfuric Acid Pickling of Steel Tube for Engine Camshaft

According to the feedback from a user th at the steel pipe supplied as the mother tube from outside presents blackened surface with pinholes and smells pungent during the pickling process before cold drawing. Accordingly the orthogonal sulfuric acid pickling test is conducted to the steel pipes with different surface states at different temperatures and in sulfuric acid solutions with different concentrations. The test results show that in case of the same temperature and holding time, along with the drop of the sulfuric acid volume fraction, the corrosion degree is dropped;and in case of the same volume fraction of the sulfuric acid, along with the increase of the temperature and the holding time, the corrosion degree goes up;and after being sunk in the sulfuric acid solution, the initial response of the bright pipe is severer than that of the oxidized pipe. The surface quality of the steel pipe and the severe degree of the smell from the pickling operation are obviously improved by means of such actions as adjusting volume fraction of the acid solubility from 20% to 15%, shortening the pickling time from 10 min to 5 min, and adjusting the temperature from 60~70 ℃ to 50~60 ℃.