ISO 9224大气腐蚀性等级的指导值标准更新解读

ISO 9224 Standard Update Interpretation for Guiding Values of the Corrosivity Categories of Atmospheres

围绕ISO 9224-2012与ISO 9224-1992的区别展开讨论,旨在对ISO 9224-2012标准的技术更新进行解读。主要技术更新有三:一是更新了金属在不同腐蚀等级的大气中的腐蚀速率的指导值;二是预测了金属在大气中的腐蚀速率,金属的腐蚀速率与暴露时间通常存在关系D=rcorrtb(当暴露时间小于20年时)或D=(t>20)rcorr[20b+b(20b-1)(t-20)](当暴露时间大于20年时);三是通过对ISO CORRAG大气暴露计划中大量数据的回归分析,得到了碳钢、锌、铜和铝的时间指数b;合金元素对钢的时间指数ba=0.596+∑biwi的影响可表示为;在海洋环境中,氯离子沉积速率Sd对时间指数增量Δb的影响为Δb=0.0845S0.26d。

This paper discusses the differences between ISO 9224-1992 and ISO 9224-2012 and interprets the technical updates in ISO 9224-2012. The main technical updates include three parts： one is updating guiding corrosion values for corrosion rate of metals in atmospheres of classified corrosivity categories. The second is predicting the corrosion attack of metals in atmospheres. The relationship between the total attack and the exposure time can be expressed as D=rcorr-tb（when t〈2Oa）or D（t〉20）=rcorr[20b＋b（20b-1）（t-20）]（when t〈2Oa）. The third is the b values were taken as the average time exponents from regression analyses of the flat panel long-term results of the ISO CORRAG atmospheric exposure programme. The relationship between ba value and alloying element can be expressed as ba=0.569＋∑biwi The relationship between Ab and the chloride deposition rate Sd can be expressed as △b=0.0845Sd-0.26.