PREN耐点蚀当量是什么意思？耐点蚀当量值PREN计算公式

点蚀当量值又称为耐点蚀当量，英文为PittingResistance EquivalentNumber，简称PREN，是一种以金属中某些元素的质量分数为基础计算的一套算法，数值常被用于耐点腐蚀比较的评定方法。在不同版本的资料中，存在着几个PREN的公式，但一般来说，这个公式是用量最广的：PREN =Cr %+ 3.3 *Mo% + 1有限公司查阅资料，查阅有一个版本的耐点蚀当量值PREN公式更为准确：PREN=Cr%+3.3 *（Mo+0.5W）%+16*N%，因一般较少几种合金含有W，故流传和广为使用的还是把W去掉的这个公式^_^具有较高的PREN值的金属表现出比PREN值低的金属更耐局部腐蚀。用这个公式计算出来的值，基本表现了相对耐点腐蚀程度。一般来说，PREN值大于32的金属可用于耐海水点腐蚀。为安全和稳定起见，PREN值大于40的材料如S31254超级不锈钢和S32750超级双相钢常用于海洋环境。抗点蚀测量方法：在ASTM G48标准中，详细规定了精确的点蚀试验流程。常见特种金属的耐点腐蚀当量PREN值如下：以上部分有钢厂的注册商标，权益归对应公司所有。来，先让小编搬出原文，英文好的读者可以自己仔细阅读下：Pitting resistance equivalentnumber (PREN) is a predictivemeasurement of a stainless steel'sresistance to localized pitting corrosionbased on its chemicalcomposition. In general: the higher PREN-value, the moreresistantis the stainless steel to localized pitting corrosion bychloride.PREN is frequently specified whenstainless steels will be exposedto seawater or other high chloridesolutions. In some instances stainlesssteels with PREN-values >32 may provide useful resistance to pitting corrosionin seawater,but is dependent on optimal conditions. However, crevicecorrosionis also a significant possibility and a PREN > 40 istypically specified forseawater service.PREN Formulas (w/w)There are several PREN formulas.The most common is PREN = 1 x %Cr+ 3.3 x %Mo + 16 x %NThere are a few stainless steelswhich add tungsten (W), for thosethe following formula is used PREN= 1 x %Cr + 3.3 ( %Mo + 0.5 x %W ) + 16 x %NPitting Resistance MeasurementExact pitting test procedures arespecified in the ASTM G48standard.