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为去除热轧不锈钢板表面的氧化层与贫铬层,钝化基体,改善表面质量,在热轧退火后需进行酸洗处理。介绍了热轧不锈钢板表面氧化层和贫铬层的组成与结构特征及其对酸洗过程的影响,并对热轧不锈钢板的酸洗体系设计和酸洗工艺开发进行了阐述。中国热轧不锈钢板普遍采用前处理(机械除鳞、中性盐电解等)→硫酸(电解)预酸洗→硝酸-氢氟酸终酸洗的酸洗工艺,旨在通过前处理和预酸洗去除大部分的氧化层,在终酸洗阶段去除残余氧化层及贫铬层,同时实现基体钝化。目前,热轧不锈钢板的酸洗工艺存在酸洗效果不稳定、贫铬层去除不完全、局部腐蚀较为严重等问题,且会产生不同程度的环境污染问题。应该根据不同钢种不同退火工艺条件下的表面氧化层与贫铬层的性质与分布特征,研究开发相应的酸洗体系和酸洗工艺。热轧不锈钢板的环保型酸洗新工艺具有广阔的发展前景。
In order to remove the oxide layer and the chromium-depleted layer on the surface of the hot-rolled stainless steel plate, the substrate is passivated to improve the surface quality, and the pickling treatment is required after the hot-rolled annealing. The composition and structure of oxide layer and chromium-depleted layer on the surface of hot-rolled stainless steel were introduced, and their effects on the pickling process were introduced. The design of pickling system and the development of pickling process for hot-rolled stainless steel sheet were also described. China hot-rolled stainless steel commonly used pre-treatment (mechanical descaling, neutral salt electrolysis) → sulfuric acid (electrolytic) pre-pickling → nitric acid - hydrofluoric acid pickling pickling process, designed to pre-treatment and pre-acid Wash to remove most of the oxide layer, remove residual oxide layer and chromium-depleted layer in the final pickling stage, while achieving matrix passivation. At present, the hot-rolled stainless steel pickling process has the problems of unstable pickling effect, incomplete removal of the chromium-depleted layer, severe localized corrosion and the like, and may cause different degrees of environmental pollution problems. Based on the properties and distribution characteristics of the surface oxide layer and the chromium-depleted layer under different annealing conditions, the corresponding pickling system and pickling process should be studied and developed. Hot-rolled stainless steel pickling new environmentally friendly process has broad prospects for development.