合金元素对耐酸钢耐蚀行为及表面缺陷的影响

EFFECT OF ALLOYING ELEMENTS ON CORROSION RESISTANCE AND SURFACE DEFECTS OF ACID-RESISTANT STEEL

耐酸钢具有比碳钢更强的耐酸性能,比耐酸不锈钢更低的合金成本,与涂镀产品相比又减少了电镀/热镀工序,在实际应用中体现出较大的应用价值。本文系统地介绍了合金元素对耐硫酸露点腐蚀钢耐蚀行为、表面质量的影响,对耐蚀钢实际生产中热轧表面缺陷产生原因进行了分析,并提出了有效改进措施。Cu、Sb、Sn、Cr元素的添加在耐硫酸腐蚀方面起着决定性作用,但是,Cu、Sb的选择性氧化会引起一系列表面质量问题,如“铜脆”和氧化铁皮色差,是工业生产的难题。研究发现,Ti能够以鳞片状富集在锈层内部,通过添加钛元素提高晶界密度;优化连铸工艺,避免铸坯在第三脆性区矫直开裂;缩短铸坯在加热炉时间、铸坯加热快速通过铜熔点区间和降低精除鳞温度等措施,在提高强度、有效消除“铜脆”缺陷的同时,还可以有效避免晶间腐蚀。在此基础上,探讨了微合金钛在耐酸钢中的作用及低成本耐酸钢的应用前景。认为,以Sn、Ti替代Sb,实现绿色环保生产,避免耐酸钢在使用过程中的全生命周期污染是新一代耐酸钢发展的趋势。

Acid-resistant steel has stronger acid-resistant properties than carbon steel,lower alloy cost than acid-resistant stainless steel,and reduces the plating/hot plating process compared with coating products,which shows greater application value in practical applications.This paper systematically introduces the influence of alloying elements on the corrosion resistance and surface quality of sulphuric acid dew point corrosion resistant steel,analyzes the causes of surface defects in hot rolling of corrosion resistant steel,and puts forward effective improvement measures.The addition of Cu,Sb,Sn and Cr elements plays a decisive role in sulfuric acid corrosion resistance,but the selective oxidation of Cu and Sb can cause a series of surface quality problems,such as"copper brittleness"and color difference of oxide scale,which is a problem in industrial production.It is found that Ti can be enriched in the rust layer in flake form,and the grain boundary density can be increased by adding titanium element.The continuous casting process was optimized to avoid the straightening and cracking of the billet in the third brittle zone.The measures such as shortening the time of the casting billet in the heating furnace,rapid heating of the casting billet through the copper melting point interval and reducing the fine descaling temperature can improve the strength and effectively eliminate the"copper brittleness"defect,but also effectively avoid intergranular corrosion.On this basis,the role of microalloy titanium in acid-resistant steel and the application prospect of low-cost acid-resistant steel are discussed.It is believed that replacing Sb with Sn and Ti,realizing green and environmental protection production,and avoiding the whole life cycle pollution of acid-resistant steel in the use process is the development trend of the new generation of acid-resistant steel.