The study of pickling process of stain steel enhanced by ultrasonic irradiation

• Main Authors: Yu-Siang Wei, 魏于翔
• Other Authors: Wen-Shing Chen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/04252421567451435058

碩士 === 雲林科技大學 === 化學工程與材料工程研究所 === 96 === Exposing to oxidizing environment, scaling always occurs on the steel surface during heating, hot-rolling and subsequent cooling.The removal of scale by pickling is a common practice before cold rolling. The thickness, chemical composition and microstructure of scale are important factors affecting the pickling efficiency. The effect of heat treatment atmosphere on the scale formation and pickling performance of 304L stainless steels (SSs) was investigated The experimental results indicate that the scale formed on 304L SS in the moist air was the most difficult to remove, while descaling was easy when the stainless steel was annealed in a reducing atmosphere ( HNO3 + HF ). The composition and microstructure of the oxides formed during annealing strongly affected the descaling performance. The scales formed on annealed 304L SS were composed mainly of FeO, FeCr2O4 and Fe3O4. SEM, Metallurgical Microscope were employed to analyze the microstructure and chemical composition of the scales formed in these steels.Using spectrophotometer measuring absorbance to ion influence.The pickling behavior was evaluated by conducting the test in ultrasonic method.SEM examination exhibited that the flat state, continuity and uniformity of the surface of the scale varied considerably. For the 304L SS , the experimental results showed the pickling time decreased with increasing pickling solution temperature and ultrasonic method in the steel.