ASTM A262-10不锈钢晶间腐蚀试验
ASTM A262-02中文翻译(自己翻译的)
检测奥氏体不锈钢晶间腐蚀敏感度的标准实施规范这个标准是在修改已有的A262后出版的，里面的数字说明的是原来版本的年份或者上个修订版的年份。
括号中的数字说明的是标准上次通过的年份。
上标数字ε表明的是上次修订或者通过的编辑的变化。
这部标准已经批准被国防部使用。
ε1 注释：表1是在2004年8月编辑校正的。
ε2 注释：30.1.5.1是在2005年1月编辑校正的。
ε3 注释：1.5和7.4节2005年7月编辑校正。
1. 范围1.1这个规范涵盖了以下五个试验：1.1.1试验A——奥氏体不锈钢的腐蚀结构分类的草酸腐蚀试验（包括从第3节到第7节）1.1.2试验B——检测奥氏体不锈钢晶间腐蚀敏感度的硫酸铁-硫酸试验（包括从第8节到第14节）1.1.3试验C——检测奥氏体不锈钢晶间腐蚀敏感度的硝酸试验（包括从第15节到第21节）1.1.4试验E——检测奥氏体不锈钢晶间腐蚀敏感度的铜-硫酸铜-硫酸试验（包括从第22节到第31节）1.1.5试验F——检测奥氏体不锈钢晶间腐蚀敏感度的铜-硫酸铜-50%硫酸试验（包括从第32节到第38节）1.2以下因素制约制约着这个规范：1.2.1所有的六个检测都要检测碳铬化物晶间腐蚀感度1.2.2铬镍钼钢中的σ相在硝酸中可导致高腐蚀速率，σ相在微观结构中也不一定可见。
1.2.3在钛或铌合金和钼合金轴承钢中的σ相在硝酸和硫酸铁-硫酸溶液中会有高腐蚀速率，铸铁轴承不锈钢合金，这种σ相在微观结构中也不一定可见。
1.3草酸腐蚀试验是一种快速的确定不锈钢试样的等级方法，这种牌号的不锈钢不会产生碳铬化合物的晶间腐蚀。
在特定的腐蚀测试条件下，这种试样腐蚀速率低，因此可以从实验中排除看是否可接受的。
1.4硫酸铁-硫酸试验，铜-硫酸铜-50％硫酸的试验，以及硝酸测试这些实验以重量减少为基础，从而为相关的试样评估提供了一个定量方法。
相反，铜-硫酸铜-16％硫酸试验主要对弯曲试样进行表观检查，因此只能确定试样是否合格。
不锈钢晶间腐蚀试验规程
1.主题内容与适用范围本标准规定了不锈钢硫酸—硫酸铜试验方法的试验设备，试验条件和步骤，试验结果的评定和试验报告的要求。
本标准适用于本厂不锈钢晶间腐蚀试验。
2.试样的选取2.1 压力加工钢材的试样从同一炉号、同一批热处理和同一规格的钢材中选取。
2.2 焊接试样从产品钢材相同而且焊接工艺也相同的试板上选取。
2.3 试样尺寸及选取方法见表一。
3.试样的制备3.1 试样用锯切取，如用剪刀时，应通过切削或研磨方法除去剪刀的影响部份。
3.2 试样上有氧化皮时，要通过切削或研磨除掉。
需要敏化处理的试样，应在敏化处理后研磨。
3.3 试样切取及表面研磨时，应防止过热，被试验的试样表面粗糙度R a必须小于0.08μm。
不能进行研磨的试样，根据双方协议也可采用其他方法处理。
试样尺寸及选取方法表一mm-35-4. 试样的敏化处理4.1 试样的敏化处理在研磨前进行。
4.2 敏化处理前试样用适当的溶剂或洗涤剂（非氧化物）去油并干燥。
4.3 含碳量大于0.08%，不含稳定化元素的钢种不进行敏化处理。
4.4 对超低碳钢（碳含量不大于0.03%时）或稳定化钢种（添加钛或铌），敏化处理温度为650℃，压力加工试样保温2小时，铸件保温1小时。
4.5 含碳量大于0.03%，不大于0.08%，不含稳定化元素并用于焊接的钢种，应以敏化处理的试样进行试验。
敏化处理制度在协议中另行规定。
4.6 焊接试样直接以焊后状态进行试验。
对焊后还要经过350℃以上热加工的焊接件，试样在焊后还应进行敏化处理，敏化处理制度在协议中另行规定。
5. 试验设备5.1 1容量为1-2L带回流冷凝器的启口—锥形烧瓶。
5.2 使试验溶液能保持微沸状态的加热装置。
6. 试验条件和步骤：6.1 试验溶液：将100g硫酸铜（GB665 分析纯）溶介于700毫升蒸馏水或离子水中，再加入100ml硫酸（GB625 优级纯），用蒸馏水或去离子水稀释至1000ml，配制成硫酸—硫酸铜溶液。
ASME晶间腐蚀作业指导书
1.Scope
1.1 Practice E—Copper-Copper Sulfate-Sulfuric Acid Test forDetecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels, and
5.3 Specimens of extra-low-carbon and stabilized grades are tested after sensitizing heat treatments at 650 to 675℃，which is the range of maximum carbide precipitation. The most commonly used sensitizing treatment is 1h at 675℃. Care should be taken to avoid carburizing or nitriding the specimens. The heat treating is bestcarriedout in air or neutral salt.
6.4 The time of the test shall be a minimum of 15h, unless a longer time is agreed upon between the purchaser and the producer.If not 15h, the test time shall be specified on the test report. Fresh test solutionwould not be needed if the test were to run 48 or even 72h.(If any adherent copper remains on the specimen, it may be removed by a brief immersion in concentrated nitric acid at room temprature).
不锈钢晶间腐蚀试验与分析
不锈钢晶间腐蚀试验与分析一、实验目的1. 掌握影响奥氏体不锈钢晶间腐蚀的因素；2. 掌握不锈钢晶间腐蚀试验的方法；二、实验原理18-8型奥氏体不锈钢在许多介质中具有高的化学稳定性，但在400-800 C范围内加热或在该温度范围内缓慢冷却后，在一定的腐蚀介质中易产生晶间腐蚀。
晶间腐蚀的特征是沿晶界进行浸蚀。
使金属丧失机械性能，致使整个金属变成粉末。
1. 晶间腐蚀产生的原因一般认为在奥氏体不锈钢中，铬的碳化物在高温下溶入奥氏体中，由于敏化(400-800 C)加热时，铬的碳化物常于奥氏体晶界处析出，造成奥氏体晶粒边缘贫铬现象，使该区域电化学稳定性下降，于是在一定的介质中产生晶间腐蚀。
为提高耐蚀性能，常采用以下两种方法。
(1)将18-8型奥氏体不锈钢碳含量降至0.03%以下，使之减少晶界处碳化物析出量，而防止发生晶间腐蚀。
这类钢成称为超低碳不锈钢，常见的有00Cr18Ni10。
(2)在18-8型奥氏体不锈钢中加入比铬更易形成碳化物的元素钛或铌，钛或铌的碳化物较铬的碳化物难溶于奥氏体中，所以在敏化温度范围内加热时，也不会于晶界处析出碳化物，不会在腐蚀性介质中产生晶间腐蚀。
为固定18-8型奥氏体不锈钢中的碳，必须加入足够数量的钛或铌，按原子量计算，钛或铌的加入量分别为钢中碳含量的4-8倍。
2. 晶间腐蚀的试验方法晶间腐蚀的试验方法有C法、T法、L法、F法和X法。
这里介绍容易实现的C 法和F法。
试样状态：(1) 含稳定化元素(Ti或Nb)或超低碳(C W 0.03%)的钢种应在固溶状态下经敏化处理的试样进行试验。
敏化处理制度为650C 保温1小时空冷。
⑵含碳量大于0.03%不含稳定化元素的钢种，以固溶状态的试样进行试验；用于焊接钢种应经敏化处理后进行试验。
(3)直接以冷状态使用的钢种，经协议可在交货状态试验。
(4)焊接试样直接以焊后状态试验。
如在焊后要在350C以上热加工，试样在焊后要进行敏化处理。
试样制备：(1) 试样从同一炉号、同一批热处理和同一规格的钢材中选取。
压力容器不锈钢晶间腐蚀的形成机理及试验方法
压力容器不锈钢晶间腐蚀的形成机理及试验方法作者：马宗萌来源：《中国化工贸易·上旬刊》2020年第02期摘要：介绍不锈钢的晶间腐蚀机理，奥氏体不锈钢在敏化温度区内，碳向晶界扩散，并且碳与铬形成碳化铬，导致晶间贫铬，晶体内外出现电位差，产生电化学腐蚀，即为晶间腐蚀。
晶间腐蚀在特定介质下无法避免，需根据腐蚀环境选择合理的材质及进行晶间腐蚀试验，以判定不锈钢是否具有晶间腐蚀倾向。
关键词：不锈钢;贫铬;晶间腐蚀1 不锈钢晶间腐蚀概述随着社会的发展，材料的进步，碳钢的大量应用让人们认识到了钢材腐蚀的严重性，以及腐蚀带来的安全事故频发。
通过向碳钢中填加合金元素发明了不锈钢。
不锈钢耐腐蚀能力很强，有优良的耐均匀腐蚀性能以及良好的力学、焊接性能，但并不是万能的。
由于奥氏体不锈钢压力容器所产生的晶间腐蚀属于局部腐蚀，隐蔽性很强，不易发现。
对压力容器的安全运行造成极大隐患，易发生安全事故。
因此本文探讨分析奥氏体不锈钢晶间腐蚀的形成原因，以及怎么采取措施降低晶间腐蚀的影响。
不锈钢因填加合金元素和冶炼方法区别形成不同的钢种。
按照钢材晶相组织结构可以分为铁素体不锈钢、奥氏体不锈钢、奥氏体--铁素体不锈钢、马氏体不锈钢、双相不锈钢和近年研发的超级不锈钢;按照化学成分可以将不锈钢分为铬镍不锈钢和铬不锈钢两大类。
奥氏体不锈钢因优异的性能和相对得到了广泛的应用。
2 不锈钢晶间腐蚀的理论基础晶间腐蚀是指不锈钢在特定的腐蚀介质接触中，晶粒、晶界、基体和晶间化合物之间形成微电池效应，导致腐蚀从金属的表面开始，沿晶界不断向晶粒内部发展，造成不锈钢晶粒间结合力降低，不锈钢强度降低，严重时会造成材料的完全失效。
晶间腐蚀虽然在不锈钢表面没有形成严重的腐蚀痕迹，外表看不出腐蚀的迹象，但晶间腐蚀为沿晶界发展的裂纹，金属原有的物理、机械性能几乎完全丧失，导致其在很小的载荷下，便有可能发生材料的破裂失效。
奥氏体不锈钢晶间腐蚀的机理是贫铬理论：不锈钢因填加铬元素而有很高的耐蚀性，经研究铬含量14%～18%的不锈钢有极佳的耐蚀性，但铬含量≤12%时其耐蚀性能和普通碳钢差不多。
不锈钢焊接接头的晶间腐蚀实验
防治措施
①采用超低碳不锈钢，含碳量希望小于 0.06% 。 ②在工艺上，尽量减小近缝区过热， 特别要避免在焊接过程中就产生“中温敏化” 的加热效果。 由此可见：“高温过热”和“中温敏化”是产 生刀蚀的必要条件。 对于焊接接头“高温过热”是焊接热循环中必 然形成的，因此只需要进行一次“中温敏化” 处理，就可根据 GB1223-75 标准进行晶间腐蚀 试验。
实验目的
一、观察与分析不锈钢焊接接头的显微 组织。 二、了解不锈钢焊接接头产生晶间腐蚀 的机理及晶间腐蚀区显微组织特征。
二、
实验装置及实验材料
（一）C法电解浸蚀装置 （二）金相显微镜 （三）吹风机 （四） 腐蚀液稀释为10%的草酸（C2H4O4· 2H2O 分析纯）水溶液1000ml （五） 实验材料1Cr18Ni9Ti(或1Cr18Ni9)钢手 弧焊或TIG焊试片40×20×1.5～3mm 6对 （六） 秒表 （七） 乙醇、丙酮、棉花、各号金相砂纸等。
三、
实验原理
1 焊接18-8型奥氏体不锈钢的接头产 生晶间腐蚀的类型及控制 18-8 型不锈钢焊接接头出现三个部位的 晶间腐蚀现象，即，焊缝腐蚀区，刀状 腐蚀区，敏化腐蚀区。但在同一个接头 中不会出现这三种晶间腐蚀区，其取决 于钢的成分。
1)
焊缝腐蚀区
焊缝腐蚀区主要与焊接材料有关，同时也受焊接工艺的影响。 （a） 防治措施：①控制焊缝金属化学成分，主要 是尽量降低含碳量和添加足够量的 Ti 和 Nb。焊缝中 Ti 和 Nb 的量 应大于钢板的量 （b）控制焊缝的组织状态，使之含有适当数量的 一次铁素体δ（δ=5%为最宜，适宜量为4～12ً%）。
2)
敏化区腐蚀
在焊接热影响区中峰值温度处于敏化温度区间的部 位所发生的腐蚀（敏化温度为450℃～ 850℃；实际区 为600℃～1000℃）。敏化区腐蚀只发生在不含Ti或Nb 的18-8不锈钢中。 防 治 措 施 ： ① 采 用 含 Ti 或 Nb 的 1 8 - 8 或 超 低 碳 00Cr18Ni11不锈钢。 ②在工艺方面，应尽可能减少热影 响取处于敏化温度区间的时间。 产生敏化腐蚀区后的处理措施：采用稳定化处理， 将处理件进行850～900℃短时加热后空冷。
ASTMG探测高镍铬合金锻件晶间腐蚀敏感度的标准实施规程中文
标准号：G28-02探测高镍铬合金锻件晶间腐蚀敏感度的标准实施规程1注1：本标准由ASTM金属腐蚀委员会G01管辖并由实验室腐蚀试验分委员会G01.05直接负责。
现行版本于2002年10月1日批准，2003年1月出版。
已出版版本有G28-71，上一个版本为G28-97。
1、范围1.1该标准涉及两种试验方法，如下所示：1.1.1方法A，硫酸铁-硫酸试验方法（包括3～10部分）—对某些服役环境下，采用沸腾硫酸铁-50%硫酸溶液，探测高镍铬合金晶间腐蚀（参考G15）敏感度的实施规程进行了描述。
对于某些合金而言，采用该方法得到的均匀腐蚀率随合金成分微量变化而变化，此时的均匀腐蚀有可能会掩盖合金的晶间腐蚀，如合金N10276、N06022、N06059和N06455。
1.1.2方法B，混合酸-氧化性盐试验（包括11～18部分）—该方法采用的试验溶液为23%硫酸+1.2%盐酸+1%氯化铁+1%氯化铜沸腾溶液。
当晶界处出现了大量析出物时，晶间腐蚀率将呈现阶梯式增加。
1.2该标准的两种方法可以测试在加工工艺或化学成分或两者共同影响下的晶间腐蚀敏感度。
此条件下存在晶间腐蚀，若换成其它环境时也许会出现，也许不会，这与具体的现场试验条件或服役条件有关系。
1.3该标准并没有对试验过程所涉及的所有安全问题进行说明。
采用该标准的用户有责任制定合适的安全规范，使用前以确保其适用性。
在 5.1.1、5.1.3、5.1.9、13.11和13.1.11中列出了相关安全参考。
2、引用文献2.1ASTM标准：A262-测试不锈钢晶间腐蚀敏感度的标准实施规程2D1193-试剂水规范3G15-腐蚀及腐蚀试验相关术语4注2：ASTM标准手册，Vol 01.03注3：ASTM标准手册，Vol 11.01注4：ASTM标准手册，Vol 03.02方法A—硫酸铁-硫酸试验3、意义和用途3.1采用沸腾硫酸铁-硫酸溶液进行试验的锻造合金有：合金试验时间，h注A: 若合金N08825的服役条件为硝酸时，采用ASTM A262-C的65%的硝酸测试其晶间腐蚀敏感性比采用硫酸铁-硫酸溶液要更好，应予以采用。
晶间腐蚀检测报告
金相照片metallograph NO. 放大倍 magnification:X1000
结论 Conclusion
检验员Tested by:
合格Conform 日期Date 校对Reviewed by:
日期Date
王丽
2011.11.25
不合格Non-conform
批准Approved by
日期Date
晶间腐蚀检测结果
报告编号 Report number
பைடு நூலகம்批次号 Lot No.
零件版本号 Part Rev.
样品数量 Sample Quantity
材料规范(版本） Material Specification
（Rev.) 设备型号 Equipment Model
检验规范(版本） Analysis Specification
声明Statement：1.此分析结果仅对来样而言。Analysis results are only for requested sample.2.未经材料 验室书面批准，不得部分复制检验报告。The report shall not be reproduced except in full without the written approval of the MTL.
（Rev.) 客户
Customer
■依据ASTM A 262 Practice A,试样经675℃保温1h敏化处理，抛光后在10%草酸溶液中电解腐蚀（电流密度1A/cm2,时间 分钟），经在X500倍金相显微镜观察，试样表面浸蚀等级符合ASTM A262 Practice C可接受的浸蚀等级。According as AST 262 ,specimens are tested after sensitizing heat treatments--1 h at 675℃.Electro-Corrosion with 10% oxalic acid(The polished specimen should be etched at 1 A/cm2 for 1.5 min.),The etched surface is examine on a metallurgical microscope at about 500X for cast steels.The etch structures classification is compl to acceptable etch structures Per ASTM A262 prctice C.
耐蚀合金标准
耐蚀合金是一种能够在恶劣环境下保持耐蚀性能的特殊材料。
它被广泛应用于化工、石油、航空航天等领域，在保证设备安全运行的同时，减少了设备维修和更换的频率，降低了成本。
为了确保耐蚀合金材料的质量和性能，有一些相关的标准可以作为参考。
1.ASTM G48 - 这个标准给出了评估耐蚀合金之间的耐蚀性能的测试方法。
它涵盖了各种环境条件下的实验，包括浸泡、旋转试样和自由腐蚀试验。
这些测试方法可以用来衡量耐蚀合金材料的耐蚀性能，并对其进行比较和分类。
2.ASTM A262 - 这个标准是用于评估耐蚀合金的晶间腐蚀倾向性的试验方法。
它包括了五种试验方法，用于检测材料是否具有晶间腐蚀破坏的倾向，这是一种常见的耐蚀合金材料的问题。
3.ASTM B117 - 这个标准是用于评估耐蚀合金在盐雾环境下的耐蚀性能的试验方法。
盐雾环境是一种常见的腐蚀环境，对于耐蚀合金材料的评估非常重要。
这个标准提供了一种可重复的试验方法，用于比较不同合金材料在盐雾环境下的性能。
4.NACE MR0175 - 这个标准是由国际腐蚀与保护协会（NACE）制定的，适用于耐蚀合金在油气工业中的应用。
它规定了耐蚀合金材料的化学成分、硬度、热处理和耐蚀性能要求，以及监测、检查和验证的方法。
5.ISO 15156 - 这个标准是使用NACE MR0175作为基础，在国际范围内遵循腐蚀和材料性能规范的指南。
它适用于涉及油气开采和相关产业的设备和材料，规定了材料的选用、测试和处理要求。
6.ASME B16.34 - 这个标准规定了阀门材料的要求，包括耐蚀合金。
它涵盖了各种不同类型（例如钢、不锈钢、镍合金等）的阀门材料，以及与耐蚀性有关的其他要求，如抗硫化物应力开裂和高温环境下的耐蚀性能。
这些标准提供了评估和比较耐蚀合金材料性能的指导，可以帮助制造商、设计师和使用者选择合适的材料，并确保其耐蚀性能满足特定环境下的要求。
这些标准还可用于监督和控制耐蚀合金材料的生产和使用，确保产品质量和安全性。
不锈钢复合板复层晶间腐蚀试验方法和标准
不锈钢复合板复层晶间腐蚀试验方法和标准分类工程技术-钢铁/有色金属一、背景非锈钢复合板是指将不同表面材料，如碳钢、不锈钢或有色金属等进行熔接，制成的一种新型金属复合板，其特性既具有钢铁等材料的强度和刚性，又具有不锈钢或有色金属等材料的耐腐蚀性能，因此得到了广泛的应用。
由于不锈钢复合板的复合性能较好，但其复合晶间腐蚀问题仍然值得关注和研究。
需要对其进行恰当的试验，并发展出一套符合当前使用情况的复层晶间腐蚀试验方法和标准。
二、试验方法和标准该试验方法是研究金属复合板不同层的表面晶间腐蚀性能的实验方法，该试验方法通常分为热处理、光学显微镜观察和电子显微镜观察3个步骤。
热处理步骤：将不锈钢复合板先经过一定的热处理处理，然后经过悬挂处理，可以获得适合试验使用的样品。
光学显微镜观察：将经过悬挂处理的复合板样品观察于光学显微镜，以检查表面缺陷，以及晶向缺陷的存在情况。
电子显微镜观察：将经过悬挂处理的样品观察于加工后的电子显微镜，记录不同层以及晶间非对称畸变的状况，定性分析其复合晶间腐蚀情况。
由于不锈钢复合板复合晶间腐蚀问题具有复杂性，根据不同材料、工况引致复合晶间腐蚀会存在不同情况，且此类复合晶间腐蚀性能的指标评价测量均具有不确定性，因此，同一工况下应尽量使用复杂的性能指标，尽可能准确的表示复合板的复层晶间腐蚀性能。
一般来说，复合晶间腐蚀评价应具备以下性能指标：①腐蚀前后金属表面比表现：由仪器记录，表示腐蚀前和腐蚀后的金属表面厚度对比。
②材料硬度：由仪器检测，表示材料腐蚀前后的硬度变化情况。
③复合晶间腐蚀深度：由仪器测量，表示复合晶间腐蚀深度情况。
三、结论本文简要研究了不锈钢复合板复合晶间腐蚀试验方法和标准，以及复合晶间腐蚀性能指标。
通过应用复层晶间腐蚀试验方法和性能指标可以进一步探究不同材料、不同工况下复合板的晶间腐蚀损伤情况，为不锈钢复合板的复合性能优化和应用提供有效参考。
晶间腐蚀的机理
二、晶间腐蚀的防止和消除 进行均匀化处理
焊后, 将奥氏体不锈钢的焊接接头重新加热至850~900℃, 保温 2 h, 使奥氏体晶粒内部的铬有充分时间扩散到晶界, 使晶界处 的含铬量又恢复到大于12%(质量分数) , 贫铬区得以消失, 这叫 均匀化处理。
二、晶间腐蚀的防止和消除 铁素体含量的影响
合格标准
பைடு நூலகம்
与钢表面敲击，有清脆 的金属敲击声 弯曲 90°，无裂纹；若 开裂，开裂边缘没有晶 间腐蚀迹象。 微观金相：作为上述两 试验的补充，在上述两 试验存在争议时，提供 判定依据
三、晶间腐蚀试验方法 核电设计中常用的奥氏体不锈钢晶间腐蚀试验方法
标准 敏化处理条件 适用范围 加 热 至 650± ， 加 热 时 间 不 超 过 5min，保温10min后，立刻水冷 低碳(C≤0.06)18-10钢 加 热 至 675± ， 加 热 时 间 不 超 过 5min，保温10min后，立刻水冷 含Mo低碳(C≤0.06)18-10钢 加 热 至 700± ， 加 热 时 间 不 超 过 RCC-M MC 5min ，保温 30min 后，缓慢随炉冷 超低碳(C≤0.03)18-10钢；含稳定化元素(Ti,Nb)的18-10 1310 却(60±/h)至后，空冷 钢 加 热 至 725± ， 加 热 时 间 不 超 过 5min ，保温 30min 后，缓慢随炉冷 含Mo超低碳(C≤0.03)18-10钢；含稳定化元素(Ti,Nb)以 却(60±/h)至后，空冷 及Mo的18-10钢 超低碳(C≤0.03)钢或稳定化钢(添加Ti或Nb)，压力加工 试件 超低碳(C≤0.03)钢或稳定化钢(添加Ti或Nb)，铸件 焊后还要进行以上热加工的焊接件
四、晶间腐蚀要求 RG1.44对于工艺评定的要求
ASTM A262 2015 奥氏体不锈钢晶间腐蚀敏感性检测标准方法
Designation:A262−15Standard Practices forDetecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels1This standard is issued under thefixed designation A262;the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(´)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1These practices cover the followingfive tests:1.1.1Practice A—Oxalic Acid Etch Test for Classification of Etch Structures of Austenitic Stainless Steels(Sections4to 13,inclusive),1.1.2Practice B—Ferric Sulfate-Sulfuric Acid Test for De-tecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels(Sections14to25,inclusive),1.1.3Practice C—Nitric Acid Test for Detecting Suscepti-bility to Intergranular Attack in Austenitic Stainless Steels (Sections26to36,inclusive),1.1.4Practice E—Copper–Copper Sulfate–Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels(Sections37to46,inclusive),and 1.1.5Practice F—Copper–Copper Sulfate–50%Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Molybdenum-Bearing Austenitic Stainless Steels(Sections 47to58,inclusive).1.2The Oxalic Acid Etch Test is a rapid method of identifying,by simple etching,those specimens of certain stainless steel grades that are essentially free of susceptibility to intergranular attack associated with chromium carbide precipitates.These specimens will have low corrosion rates in certain corrosion tests and therefore can be eliminated (screened)from testing as“acceptable.”The etch test is applicable only to those grades listed in the individual hot acid tests and classifies the specimens either as“acceptable”or as “suspect.”1.3The ferric sulfate-sulfuric acid test,the copper–copper sulfate–50%sulfuric acid test,and the nitric acid test are based on weight loss determinations and,thus,provide a quantitative measure of the relative performance of specimens evaluated.In contrast,the copper–copper sulfate–16%sulfuric acid test is based on visual examination of bend specimens and,therefore, classifies the specimens only as acceptable or nonacceptable.1.4The presence or absence of intergranular attack in these tests is not necessarily a measure of the performance of the material in other corrosive environments.These tests do not provide a basis for predicting resistance to forms of corrosion other than intergranular,such as general corrosion,pitting,or stress-corrosion cracking.N OTE1—See Appendix X1for information regarding test selection.1.5The values stated in SI units are to be regarded as standard.The inch-pound equivalents are in parentheses and may be approximate.1.6This standard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Some specific hazards statements are given in10.1,20.1.1,20.1.9,31.3,34.4, 53.1.1,and53.1.10.2.Referenced Documents2.1ASTM Standards:2A370Test Methods and Definitions for Mechanical Testing of Steel ProductsA380/A380M Practice for Cleaning,Descaling,and Passi-vation of Stainless Steel Parts,Equipment,and Systems D1193Specification for Reagent WaterE3Guide for Preparation of Metallographic Specimens 2.2ASME Code:3ASME Boiler&Pressure Vessel Code,Section IX2.3ACS Specifications:4Reagent Chemicals,Specifications and Procedures1These practices are under the jurisdiction of ASTM Committee A01on Steel, Stainless Steel and Related Alloys and are the direct responsibility of Subcommittee A01.14on Methods of Corrosion Testing.Current edition approved Sept.1,2015.Published September2015.Originally approved st previous edition approved in2014as A262–14.DOI: 10.1520/A0262-15.2For referenced ASTM standards,visit the ASTM website,,or contact ASTM Customer Service at service@.For Annual Book of ASTM Standards volume information,refer to the standard’s Document Summary page on the ASTM website.3Available from American Society of Mechanical Engineers(ASME),ASME International Headquarters,Two Park Ave.,New York,NY10016-5990,http:// .4Available from American Chemical Society(ACS),1155Sixteenth Street,NW, Washington,DC20036,*A Summary of Changes section appears at the end of this standard Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959.United States2.4ISO Standard:5ISO 3651-2Determination of Resistance to Intergranular Corrosion of Stainless Steels—Part 2:Ferritic,Austenitic,and Ferritic-Austenitic (Duplex)Stainless Steels—Corrosion Test in Media Containing Sulfuric Acid 3.Purity of Reagents3.1Purity of Reagents—Reagent grade chemicals shall be used in all tests.Unless otherwise indicated,it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society 6where such specifications are available.Other grades may be used,provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the test result.3.2Purity of Water—Unless otherwise indicated,references to water shall be understood to mean reagent water as defined by Type IV of Specification D1193.PRACTICE A—OXALIC ACID ETCH TEST FOR CLASSIFICATION OF ETCH STRUCTURES OFAUSTENITIC STAINLESS STEELS (1)74.Scope4.1The Oxalic Acid Etch Test is used for acceptance of wrought or cast austenitic stainless steel material but not for rejection of e of A262Practice A as a stand-alone test may reject material that the applicable hot acid test would find acceptable;such use is outside the scope of this practice.4.2This test is intended to be used in connection with other evaluation tests described in these practices to provide a rapid method for identifying qualitatively those specimens that are certain to be free of susceptibility to rapid intergranular attack in these other tests.Such specimens have low corrosion rates in the various hot acid tests which require from 15to 240h of exposure.These specimens are identified by means of their etch structures,which are classified according to the criteria given in Section 11.4.3The Oxalic Acid Etch Test may be used to screen specimens intended for testing in Practice B—Ferric Sulfate-Sulfuric Acid Test,Practice C—Nitric Acid Test,Practice E—Copper-Copper Sulfate–16%Sulfuric Acid Test,and Prac-tice F—Copper-Copper Sulfate–50%Sulfuric Acid Test.4.4Each of these other practices contains a table showing which classifications of etch structures on a given stainless steel grade are equivalent to acceptable or suspect performance in that particular test.Specimens having acceptable etch structures need not be subjected to the hot acid test.Specimens having suspect etch structures must be tested in the specified hot acid solution.4.5There are two classes of specimens to be considered:base metal,and process-affected metal.4.5.1Process-affected metal contains any condition that affects the corrosion properties of the material in a non-uniform way,such as (but not limited to)welds;carburized.nitrided,or oxidized surfaces;mechanical deformation;and areas affected by heat.Base metal has none of these conditions.4.5.2Because Practices B,C,and F involve immersing the entire specimen and averaging the mass loss over the total specimen area,and because welding,carburization,mechanical deformation,and the like affect only part of a specimen,the presence of process-affected metal in a specimen can affect the test result in an unpredictable way depending on the propor-tions of the area affected.4.5.3If the presence of these or other localized conditions is a concern to the purchaser,then tests that do not average the mass loss over the total specimen surface area,such as Practice A,the Oxalic Acid Etch Test,or Practice E,the Copper–Copper Sulfate–Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels,should be considered.5.Summary of Practice5.1A specimen representative of the material to be evalu-ated is polished to a specified finish and over-etched using oxalic acid electrolytically.The etched specimen is then examined using a metallurgical microscope.The etched struc-ture is compared with reference photographs to determine whether the material is acceptable or suspect.Suspect material is then subjected to the specified hot acid immersion test.6.Significance and Use6.1Use of the etch test allows rapid acceptance of specific lots of material without the need to perform time-consuming and costly hot acid immersion tests on those lots.7.Apparatus7.1Etching Cell:7.1.1An etching cell may be assembled using components as described in this section.Alternatively,a commercial electropolisher/etcher (as used for metallographic sample preparation)may be used for small specimens provided the current density requirement of 10.2is met.7.1.2Source of Direct Current—Battery,generator,or rec-tifier capable of supplying about 15V and 20A.7.1.3Ammeter—For direct current;used to measure the current on the specimen to be etched.7.1.4Variable Resistance—Used to control the current on the specimen to be etched.7.1.5Cathode—A stainless steel container,for example,a 1-L (1-qt)stainless steel beaker.7.1.5.1Alternate Cathode—A piece of flat stainless steel at least as large as the specimen surface.7.1.6Electrical Clamp—To hold the specimen to be etched and to complete the electrical circuit between the specimen and the power source such that the specimen is the anode of the cell.5Available from International Organization for Standardization (ISO),1,ch.de la V oie-Creuse,CP 56,CH-1211Geneva 20,Switzerland,.6For suggestions on the testing of reagents not listed by the American Chemical Society,see Analar Standards for Laboratory Chemicals ,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeia and National Formulary ,U.S.Pharma-copeial Convention,Inc.(USPC),Rockville,MD.7The boldface numbers in parentheses refer to a list of references at the end of thisstandard.--`,`,``,``,`,,`,,,,,,```,`,,```-`-`,,`,,`,`,,`---7.1.7The power source,resistor,and ammeter must be sized appropriately for providing and controlling the current as specified in10.2of this practice.7.1.8As described,the electrolyte container is the cathode; it may be a stainless steel beaker or fabricated from stainless steel such as by welding a section of tube or pipe to aflat plate or sheet.Alternatively,the electrolyte container may be glass (or other non-conducting,corrosion resisting material)in lieu of a stainless steel container,and the cathode may be aflat plate or sheet of a corrosion resisting alloy.In this latter case,theflat surface of the cathode must be at least as large as,facing,and approximately centered on,the prepared surface of the speci-men.Other configurations of the electrodes might not provide uniform etching over the specimen surface.In any case,the size and shape of the specimen dictate the size and construction of the etching cell and of the power source and controls.The overriding principle is that the etch needs to be uniform over the surface to be examined.7.2Metallurgical Microscope—For examination of etched microstructures at250to500diameters.8.Reagents and Materials8.1Etching Solution(10%)—Dissolve100g of reagent grade oxalic acid crystals(H2C2O4·2H2O)in900mL of reagent water.Stir until all crystals are dissolved.8.1.1Alternate Etching Solution(See10.7)—Dissolve100g of reagent grade ammonium persulfate((NH4)2S2O8)in 900mL of reagent water.Stir until dissolved.9.Sampling and Test Specimens9.1The specified hot acid test provides instructions for sampling and for specimen preparation such as a sensitization heat treatment.Additional instructions specific to Practice A follow:9.2The preferred specimen is a cross-section including the product surface to be exposed in service.Only suchfinishing of the product surface should be performed as is required to remove foreign material.9.3Whenever practical,use a cross-sectional area of1cm2 or more.If any cross-sectional dimension is less than1cm, then the other dimension of the cross-section should be a minimum of1cm.When both dimensions of the product are less than1cm,use a full cross section.9.4Polishing—On all types of materials,polish cross sec-tional surfaces through CAMI/ANSI600[FEPA/ISO P1200]in accordance with Guide E3prior to etching and examination. Not all scratches need to be removed.10.Procedure10.1(Warning—Etching should be carried out under a ventilated hood.Gas,which is rapidly evolved at the electrodes with some entrainment of oxalic acid,is poisonous and irritating to mucous membranes.)10.2Etch the polished specimen at1A/cm2for1.5min.10.2.1To obtain the correct specified current density: 10.2.1.1Measure the total immersed area of the specimen to be etched in square centimetres.10.2.1.2Adjust the variable resistance until the ammeter reading in amperes is equal to the total immersed area of the specimen in square centimetres.10.3A yellow-greenfilm is gradually formed on the cath-ode.This increases the resistance of the etching cell.When this occurs,remove thefilm by rinsing the inside of the stainless steel beaker(or the steel used as the cathode)with an acid such as30%HNO3.10.4The temperature of the etching solution gradually increases during etching.Keep the temperature below50°C. This may be done by alternating two containers.One may be cooled in tap water while the other is used for etching.10.4.1The rate of heating depends on the total current (ammeter reading)passing through the cell.Therefore,keep the area to be etched as small as possible while at the same time meeting the requirements of desirable minimum area to be etched.10.5Avoid immersing the clamp holding the specimen in the etching solution.10.6Rinsing—Following etching,rinse the specimen thor-oughly in hot water and then in acetone or alcohol to avoid crystallization of oxalic acid on the etched surface during drying.10.7It may be difficult to reveal the presence of step structures on some specimens containing molybdenum(AISI 316,316L,317,317L),which are free of chromium carbide sensitization,by electrolytic etching with oxalic acid.In such cases,an alternate electrolyte of ammonium persulfate may be used in place of oxalic acid.(See8.1.1.)An etch for5or10 min at1A/cm2in a solution at room temperature readily develops step structures on such specimens.11.Classification of Etch Structures11.1Examine the etched surface on a metallurgical micro-scope at250×to500×for wrought steels and at about250×for cast steels.11.2Examine the etched cross-sectional areas thoroughly by complete traverse from inside to outside diameters of rods and tubes,from face to face on plates.11.2.1Microscopical examination of a specimen shall be made on metal unaffected by cold-working,carburization, welding,and the like.If any of these conditions are found,note their presence in the report.11.3Classify the etch structures into the following types (Note2):11.3.1Step Structure(Fig.1)—Steps only between grains, no ditches at grain boundaries.11.3.2Dual Structure(Fig.2)—Some ditches at grain boundaries in addition to steps,but no single grain completely surrounded by ditches.11.3.3Ditch Structure(Fig.3)—One or more grains com-pletely surrounded by ditches.11.3.4Isolated Ferrite(Fig.4)—Observed in castings and welds.Steps between austenite matrix and ferrite pools. 11.3.5Interdendritic Ditches(Fig.5)—Observed in castings and welds.Deep interconnectedditches.--` , ` , ` ` , ` ` , ` , , ` , , , , , , ` ` ` , ` , , ` ` ` -` -` , , ` , , ` , ` , , ` ---11.3.6End-Grain Pitting I (Fig.6)—Structure contains a few deep end-grain pits along with some shallow etch pits at 500×.(Of importance only when the nitric acid test is used.)11.3.7End-Grain Pitting II (Fig.7)—Structure contains numerous,deep end-grain pits at 500×.(Of importance only when nitric acid test is used.)N OTE 2—All photomicrographs were made with specimens that were etched under standard conditions:10%oxalic acid,room temperature,1.5min at 1A/cm 2.11.4The evaluation of etch structures containing only steps and of those showing grains completely surrounded by ditches in every field can be carried out relatively rapidly.In cases that appear to be dual structures,more extensive examination is required to determine if there are any grains completely encircled.If an encircled grain is found,classify the steel as a ditch structure.11.4.1On stainless steel castings (also on weld metal),the steps between grains formed by electrolytic oxalic acid etching tend to be less prominent than those on wrought materialsorFIG.1Step Structure (500×)(Steps Between Grains,No Ditchesat GrainBoundaries)FIG.2Dual Structure (250×)(Some Ditches at Grain Boundaries in Addition to Steps,but No One Grain CompletelySurrounded)FIG.3Ditch Structure (500×)(One or More Grains CompletelySurrounded byDitches)FIG.4Isolated Ferrite Pools (250×)(Observed in Castings and Welds.Steps Between Austenite Matrix and FerritePools)--`,`,``,``,`,,`,,,,,,```,`,,```-`-`,,`,,`,`,,`---are entirely absent.However,any susceptibility to intergranular attack is readily detected by pronounced ditches.11.4.2Some wrought specimens,especially from bar stock,may contain a random pattern of pits.If these pits are sharp and so deep that they appear black (Fig.7)it is possible that the specimen may be susceptible to end grain attack in nitric acid only.Therefore,even though the grain boundaries all have stepstructures,specimens having as much or more end grain pitting than that shown in Fig.7cannot be safely assumed to have low nitric acid rates and should be subjected to the nitric acid test whenever it is specified.Such sharp,deep pits should not be confused with the shallow pits shown in Figs.1and e of Etch Structure Classifications12.1The use of these classifications depends on the hot acid corrosion test for which stainless steel specimens are being screened by etching in oxalic acid and is described in each of the practices.13.Precision and Bias13.1Precision and Bias—No information is presented about either the precision or bias of Practice A—Oxalic Acid Etch Test for classification of Etch Structures of Austenitic Stainless Steels since the test result is nonquantitative.PRACTICE B—FERRIC SULFATE–SULFURIC ACID TEST FOR DETECTING SUSCEPTIBILITYTO INTERGRANULAR ATTACK IN AUSTENITIC STAINLESS STEELS (2)14.Scope14.1This practice describes the procedure for conducting the boiling 120-h ferric sulfate–50%sulfuric acid test which measures the susceptibility of austenitic stainless steels to intergranular attack.14.2The presence or absence of intergranular attack in this test is not necessarily a measure of the performance of the material in other corrosive environments.The test does not provide a basis for predicting resistance to forms ofcorrosionFIG.5Interdendritic Ditches (250×)(Observed in Castings andWelds.Deep InterconnectedDitches)N OTE 1—To differentiate between the types of pits,use a magnification of 500×and focus in the plane of etched surface.The pits which now appear completely black are end grain pits.FIG.6End Grain Pitting I (500×)(A Few Deep End Grain Pits(See 1in Figure)and Shallow Etch Pits(2))N OTE 1—This or a greater concentration of end grain pits at 500×(using standard etching conditions)indicates that the specimen must be tested when screening is for nitric acid test.FIG.7End Grain Pitting II(500×)--`,`,``,``,`,,`,,,,,,```,`,,```-`-`,,`,,`,`,,`---other than intergranular,such as general corrosion,pitting,or stress-corrosion cracking.15.Summary of the Ferric Sulfate-Sulfuric Acid PracticeB15.1A specimen representative of the material to be evalu-ated is immersed in a boiling solution of ferric sulfate and sulfuric acid for a specified time.The resulting mass loss is converted to a corrosion rate,which is compared to a specified maximum value to determine whether the material has the resistance to attack expected of the grade of material being tested.16.Significance and Use16.1The ferric sulfate-sulfuric acid test detects susceptibil-ity to intergranular attack associated primarily with chromium carbide precipitate in unstabilized austenitic stainless steels, and to intergranular attack associated with sigma phase. 16.2The corrosion potential of the ferric sulfate-sulfuric acid test has been reported as0.6V versus a standard calomel electrode(SCE),as compared with0.75to1.0V for Practice C, and0.1V for Practices E and F.(3)N OTE3—A higher corrosion potential indicates more severely oxidizing conditions.17.Rapid Screening Test17.1Before testing in the ferric sulfate-sulfuric acid test, specimens of certain grades of stainless steels(see Table1) may be given a rapid screening test in accordance with procedures given in Practice A,Oxalic Acid Etch Test for Classification of Etch Structures of Austenitic Stainless Steels. Preparation,etching,and the classification of etch structures are described therein.The use of etch structure evaluations in connection with the ferric sulfate-sulfuric acid test is specified in Table1.17.2Heat treat the material in accordance with22.1prior to performing the etch test.17.3Ignore“process-affected”areas(see Section21);ap-plication of the ferric sulfate-sulfuric acid test to process-affected areas is currently outside the scope of Practice B. 17.4Corrosion test specimens having acceptable etch struc-tures in the Oxalic Acid Etch Test will be essentially free of intergranular attack in the ferric sulfate-sulfuric acid test.Such specimens are acceptable without testing in the ferric sulfate-sulfuric acid test.All specimens having suspect etch structures shall be tested in the ferric sulfate-sulfuric acid test.18.Apparatus18.1The apparatus is illustrated in Fig.8.N OTE4—Other ground glass joints,such as the45/40joint may also be used.18.1.1An Allihn condenser with a minimum of four bulbs and with a ground glass joint to match that of theflask. 18.1.1.1Substitutions for this condenser orflask are not allowed.Specifically,the cold-finger type of condenser with standard Erlenmeyerflasks shall not be used.Corrosion rates obtained using the cold-finger type of condenser are lower than those obtained using the Allihn type of condenser whether due to loss of vapor or to higher oxygen content in the solution or both.Such lower corrosion rates lead to acceptance of material that should be rejected.18.1.2A1-L Erlenmeyerflask with a ground glass joint to match that of the condenser.Theflask opening limits the size of the specimen;a larger opening is desirable.TABLE1Use of Etch Structure Classifications from the Oxalic Acid Etch Test with Ferric Sulfate-Sulfuric Acid Test AGrade Acceptable EtchStructuresSuspect Etch Structures B304Step,dual,end grain,I&II Ditch304L Step,dual,end grain,I&II Ditch316Step,dual,end grain,I&II Ditch316L Step,dual,end grain,I&II Ditch317Step,dual,end grain,I&II Ditch317L Step,dual,end grain,I&II DitchCF-3Step,dual,isolated ferrite pools Ditch,interdendritic ditches CF-8Step,dual,isolated ferrite pools Ditch,interdendritic ditches CF-3M Step,dual,isolated ferrite pools Ditch,interdendritic ditches CF-8M Step,dual,isolated ferrite pools Ditch,interdendritic ditches A Grades not listed in this table either have not been evaluated for use of Practice A with Practice B or have been found to give acceptable results in the etch test while giving unacceptable results in Practice B.In the latter case Practices A would pass material that should have been subjected to the ferric sulfate-sulfuric acid test.B Specimens havingthese structures shall be tested in the ferric sulfate-sulfuricacid test.FIG.8Apparatus for Ferric Sulfate-Sulfuric Acid Test--`,`,``,``,`,,`,,,,,,```,`,,```-`-`,,`,,`,`,,`---18.1.3Glass cradle(Note5)—Can be supplied by a glass-blowing shop.It must be sized so as tofit,with the specimen, through theflask opening.It must be designed to allow free flow of the testing solution around the specimen.N OTE5—Other equivalent means of specimen support,such as glass hooks or stirrups,may also be used.18.1.4Boiling Chips—Used to prevent bumping.18.1.5High Vacuum Silicone Grease—For the ground glass joint.18.1.6Hot plate,capable of providing heat for continuous boiling of the solution.18.1.7An analytical balance capable of weighing to the nearest0.001g.N OTE6—During testing,there is some deposition of iron oxides on the upper part of the Erlenmeyerflask.This can be readily removed,after test completion,by boiling a solution of10%hydrochloric acid in theflask.18.1.8Desiccator—For storage of prepared specimens prior to testing.19.Reagents and Materials19.1Ferric Sulfate Hydrate(Fe2(SO4)3·xH2O),about75% (Fe2(SO4)3)by mass.19.1.1Ferric sulfate is a specific additive that establishes and controls the corrosion potential.Substitutions are not permitted.19.2Sulfuric Acid(H2(SO)4),95.0to98.0%by mass.20.Ferric Sulfate-Sulfuric Acid Test Solution20.1Prepare600mL of50%(49.4to50.9%)solution as follows:20.1.1(Warning—Protect the eyes and use rubber gloves for handling acid.Place the testflask under a hood.)20.1.2First,measure400.0mL of Type IV reagent water and pour into the Erlenmeyerflask.20.1.3Then measure236.0mL of reagent-grade sulfuric acid.Add the acid slowly and with constant stirring to the water in the Erlenmeyerflask to avoid boiling by the heat evolved.N OTE7—Loss of vapor results in concentration of the acid.20.1.4Weigh25g of reagent-grade ferric sulfate to the nearest0.1g and add to the sulfuric acid solution.20.1.5Drop boiling chips into theflask.20.1.6Lubricate ground glass joint with silicone grease.20.1.7Coverflask with condenser and circulate cooling water.20.1.8Boil the solution until all ferric sulfate is dissolved (see Note7).20.1.9(Warning—It has been reported that violent boiling resulting in acid spills can occur.It is important to ensure that the concentration of acid does not increase and that an adequate number of boiling chips(which are resistant to attack by the test solution)are present.)21.Sampling21.1Obtain and prepare only base metal samples.21.1.1There are two classes of specimens to be considered: base metal,and process-affected metal.Process-affected metal contains any condition that affects the corrosion properties of the material in a non-uniform way,such as(but not limited to) welds;carburized.nitrided,or oxidized surfaces;mechanical deformation;and areas affected by heat.Base metal has none of these conditions.21.1.2The Practice B test involves immersing the entire specimen and averaging the mass loss over the entire surface of the specimen.Welding,carburization,mechanical deformation, and the like,affect only part of a specimen.21.1.3The mass loss rate from process-affected metal is expected to differ from that from base metal;the presence of process-affected metal in a specimen will affect the calculated test result in an unpredictable way.21.1.4If the presence of these or other localized conditions is a concern to the purchaser,then tests that do not average the mass loss over the total specimen surface area,such as Practice A,the Oxalic Acid Etch Test,or Practice E,the Copper–Copper Sulfate–16%Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels,should be considered.Details of the test and acceptance criteria shall be as agreed by the purchaser and producer.21.2Unless otherwise specified by the purchaser,the pro-cedures for obtaining representative base metal samples,for removing the specimens from the samples,and the number of specimens shall be at the discretion of the producer.22.Preparation of Test Specimens22.1Heat treat extra-low carbon and stabilized grades at 650to675°C(1200to1250°F),which is the range of maximum carbide precipitation,prior to testing.The length of time of heating,and the method of subsequent cooling used for this sensitizing treatment together with the corresponding maximum permissible corrosion rate shall be as agreed be-tween the material producer and purchaser.N OTE8—The most commonly used sensitizing treatment is1h at 675°C(1250°F).22.2Prepare the specimens,each having a total surface area of5to20cm2.22.3Where feasible for the product form,grind all the specimen surfaces using CAMI/ANSI120[FEPA/ISO P120] paper-backed,wet or dry,closed coated abrasive paper,with water as a coolant.If abrasive paper is used dry,polish slowly to avoid overheating.Do not use abrasives with grinding aids; some grinding aids containfluorides that can affect the measured corrosion rate.22.4Remove all traces of oxide scale and heat tint formed during heat treatments.Any scale that cannot be removed by grinding(for example,in stamped numbers)may be removed by using one of the pickling solutions described in Practice A380/A380M,Table A1.1.(Residual oxide scale causes gal-vanic action and consequent activation in the test solution.)22.5Measure the specimens,including the inner surfaces of any holes,to the nearest0.05mm(0.001in.)and calculate the total exposed area.22.6Degrease the specimens using suitable nonchlorinated agents,such as soap and lukewarm water,or acetone.Drythe --` , ` , ` ` , ` ` , ` , , ` , , , , , , ` ` ` , ` , , ` ` ` -` -` , , ` , , ` , ` , , ` ---。
奥氏体不锈钢焊接接头的晶间腐蚀实验指导书
奥氏体不锈钢焊接接头的晶间腐蚀实验指导书奥氏体不锈钢焊接接头的晶间腐蚀实验报告课程名称：金属焊接性班级：焊接学号： 0907074223 姓名：韩月明组别：第组同组者：尹英宝，马宝宇，于天洋，赵金哲，王志远日期： 2012..6.20一、实验目的：1、观察与分析奥氏体不锈钢焊接接头的显微组织。
2、了解奥氏体不锈钢焊接接头产生晶间腐蚀的机理及晶间腐蚀区显微组织特征。
二、实验原理：晶间腐蚀是沿晶粒边界发生的腐蚀现象。
现以18—8型奥氐体不锈钢中最常用的含稳定元素的1Cr18Ni9Ti 钢为例，来讨论晶间腐蚀的问题。
1Cr18Ni9Ti 钢含0.02%C 和0.8%Ti 。
碳在室温奥氏体中的最大溶解度低于0.03%，多余的碳则通过固熔处理与钛结合形成稳定的碳化物TiC 。
由于钛对碳的固定作用，避免了在晶界形成碳化铬，从而防止了晶间腐蚀的产生。
故1Cr18Ni9Ti 钢具有抗晶间腐蚀能力，一般不会产生晶间腐蚀现象。
然而在焊接接头中，情况有所不同。
奥氏体不锈钢的焊接接头，通常可分为以下几个区域(见图1) (一) 焊缝金属主要为柱状树枝晶。
(二) 过热区加热超过1200℃的近缝区，晶粒有明显的长大。
(三) 敏化区加热峰值温度在600℃—1000℃的区域，组织无明显变化。
对不含稳定化元素的18—8钢，可能出现晶界碳化铬的析出。
产生贫铬层，有晶间腐蚀倾向。
(四) 母材金属对于含稳定化元素的18—8钢，如1Cr18Ni9Ti 钢，峰值温度超过1200℃的过热区发生TiC 分解量愈大(图2)，从而使稳定化作用大为减弱，甚至完全消失。
在随后的冷却过程中，由于碳原子的体积很小，扩散能力比钛原子强，碳原子趋于向奥氏体晶界扩散迁移，而钛原子则来不及扩散仍保留在奥氏体点阵节点上。
因此，碳原子析集于晶界附近成为过饱和状态。
当上述过热区再次受到600—800℃中温敏化加热或长期工作在上述温度范围时，碳原子优先以很快的速度向晶界扩散。
奥氏体不锈钢焊接接头晶间腐蚀试验
三、晶间腐蚀试验方法 核电设计中常用的奥氏体不锈钢晶间腐蚀试验方法
标准号 试样尺寸 ASTM A262E GB/T4334 E RCC-M MC1300 5-13 厚 ,9-25 宽 , 最 小 80-100 长 ， 20mm 厚 ,3-4mm 长 × 宽 × 厚 75mm长 厚 70×10×4mm 试样数量： 3 个， 1 个参 考试样，1个焊后热处理 态试样(若产品需要焊后 热处理态 ) ， 1 个经敏化 处理后的试样； 675 650 700 1h 2h 加热至700±，加热时间 不 超 过 5min ， 保 温 30min 后 ， 缓 慢 随 炉 冷 却(60±/h)至后，空冷 将 硫 酸 铜 将 硫 酸 铜 质量百分比： 10% 结晶 (CuSO4· 5H2O) 溶 解 于 (CuSO4· 5H2O)(GB/T 665 分 硫酸铜， 10% 硫酸 ( 密度 700ml 蒸馏水中，再加 析纯 ) 溶解于 700ml 蒸馏水或 1.83)，80%蒸馏水 入100ml硫酸(比重1.84)， 去离子水中，再加入 100ml 用 蒸 馏 水 稀 释 至 纯硫酸(GB/T 625 优级)，用 1000ml( 质量百分比： 蒸 馏 水 或 去 离 子 水 稀 释 至 约 6% 无 水 硫 酸 铜 ， 1000ml 16%硫酸)
一、晶间腐蚀的机理 晶间腐蚀机理
1)晶间区偏析杂质或第二相选择性溶解理论 非敏化态晶间腐蚀机理主要是晶间区偏析杂质或第二相选 择性溶解理论。 该理论认为，偏析于晶界上的杂质元素(如P和Si)或沉淀析 出相(如σ相或亚显微的σ相)的选择性溶解是引起晶间腐蚀 的原因。 2)贫Cr理论 奥氏体不锈钢敏化态晶间腐蚀的机理主要是贫Cr理论。
二、晶间腐蚀的防止和消除 控制加热温度和时间
检测奥氏体不锈钢晶间腐蚀敏感度的标准规程ASTM A262(中文翻译版)
检测奥氏体不锈钢晶间腐蚀敏感度的标准规程ASTM A262（中文翻译版）1这些规程由ASTM钢、不锈钢和相关合金委员会A01管辖，并由腐蚀试验方法小组委员会A01.14直接负责。
现行版本于2015年9月1日批准。
2015年9月出版。
最初批准于1943年。
上一版于2014年批准为A262-14。
DOI: 10.1520/A0262-15。
本标准以固定名称A262发布；紧跟在名称后面的数字表示最初采用的年份，如果是修订，则表示最后修订的年份。
括号中的数字表示上次重新批准的年份。
上标（ε）表示自上次修订或重新批准以来的编辑性修改。
本标准经美国国防部机构批准使用。
1.范围1.1本规程包括以下五个试验：1.1.1实验A——奥氏体不锈钢浸蚀结构分级的草酸浸蚀试验（4至13章）。
1.1.2实验B——检测奥氏体不锈钢晶间腐蚀敏感度的硫酸铁-硫酸试验（14至25章）。
1.1.3实验C——检测奥氏体不锈钢晶间腐蚀敏感度的硝酸试验（26至36章）。
1.1.4实验E——检测奥氏体不锈钢晶间腐蚀敏感度的铜-硫酸铜-硫酸试验（37至46章）。
1.1.5实验F——检测钼-耐蚀奥氏体不锈钢晶间腐蚀敏感度的铜-硫酸铜-50%硫酸试验（47至58章）。
1.2草酸浸蚀试验是用样品浸蚀法鉴别某些不锈钢品级试样的快速方法，这些品级试样对与碳化铬沉积相关的晶间腐蚀肯定不敏感。
这些试样在某些腐蚀试验中具有低腐蚀率，因此，作为“可接收的”，可从试验中撤消（筛选）。
浸蚀试验只适用于各种热酸试验所列的那些等级钢材，样本可分级为“可接收的”或“可疑的”。
1.3硫酸铁-硫酸试验、铜-硫酸铜-50%硫酸试验和硝酸试验基于重量损耗测定，因此，提供被评估试样相关性能的定量度量。
相反，铜-硫酸铜-16%硫酸试验基于弯曲试样的目视检查，因此，只将试样分级为可验收的或不可验收的。
1.4这些试验中是否存在晶间腐蚀未必能度量材料在其它腐蚀环境中的性能。
这些试验不提供一种预测形成除了晶间腐蚀之外的腐蚀抗力的基本原则，例如普通腐蚀，点蚀或应力腐蚀开裂。
2010ASTMA262奥氏体不锈钢晶间腐蚀敏感性的测定中文版
标准名称：A262-10奥氏体不锈钢晶间腐蚀敏感性的测定标准1这个标准是在既定A262标准指导下发行的；紧接标准号后面的数字表明最初采用或上一次修订的年份。
括号内的数字表示上一次重新批准的年份。
上角标希腊字母（ε）表示自上次修订或重新批准的编辑上的变化。
这个标准被国防部代理处批准使用。
1.使用范围1.1测定包括以下5个试验方法:1.1.1 A法-奥氏体不锈钢草酸浸蚀组织分类试验方法(从第3节至第7节),1.1.2 B法-奥氏体不锈钢硫酸-硫酸铁测定晶间腐蚀敏感性试验方法(从第8节至第14节), 1.1.3 C法-奥氏体不锈钢硝酸测定晶间腐蚀敏感性试验方法(从第15节至第21节),1.1.4 E法-奥氏体不锈钢铜屑-硫酸铜-硫酸测定晶间腐蚀敏感性试验方法(从第22节至第31节),1.1.5 F法-含钼铸造奥氏体不锈钢铜屑-硫酸铜-50%硫酸测定晶间腐蚀敏感性试验方法(从第32节至第38节)。
1.2以下因素影响着这些方法的测定:1.2.1在所有6个试验方法中都可以检测出晶间腐蚀敏感性和碳化铬析出的关系。
1.2.2含铬镍钼锻钢中的σ相，无论显微组织下存在与否只会在硝酸中产生很高的腐蚀率。
1.2.3含钛或铌稳定化合金中的σ相和含钼铸造不锈钢合金中的σ相，无论显微组织下存在与否，都会在硝酸和硫酸-硫酸铁溶液中产生很高的腐蚀率。
1.3草酸浸蚀试验方法是一种通过对试样简单浸蚀快速筛选的方法，某些不锈钢试样的晶间腐蚀敏感性与碳化铬的析出基本上没有关系。
这些试样在某种腐蚀试验方法中有很小的腐蚀率，因此，可以当作是“可接受的”从试验中筛选出来。
1.4硫酸-硫酸铁试验方法，铜屑-硫酸铜-50%硫酸试验方法和硝酸试验方法依靠试样重量损失的测定，对所测试样的相对性能提供一个数量上的检测。
相比之下，铜屑-硫酸铜-16%硫酸试验方法依靠对弯曲试样的目测检验，因此试样只分为可接受的和不可接受的。
1.5在多数情况下，15小时的铜屑-硫酸铜-16%硫酸试验方法或者是120小时的硫酸-硫酸铁试验方法，与草酸浸蚀试验方法结合起来可以在最短的时间内提供需要的信息。
10%草酸晶间腐蚀试验报告(各种腐蚀组织)
合格判定： Judgement
合格（Acceptable）
试验员
Inspector
审核
Check by
伍思遥 伍素仁
日期
Date
日期
Date
2012.3.26 2012 年.3.26
XXXX 不 锈 钢 管 有 限 公 司
XXXX Stainless Steel Pipe Co.,Ltd
晶间腐蚀试验报告
审核
Check
伍思遥 伍素仁
日期
Date
日期
Date
2012.3.26 2012 年.3.26
XXXX 不 锈 钢 管 有 限 公 司
XXXX Stainless Steel Pipe Co.,Ltd
晶间腐蚀试验报告
Testing Report of Intergranular Corrosion
试样尺寸
横截表面抛光，面积为
Sample Dimensions(mm)
25*25*5
试样处理 Sample condition
1.25cm2（≥ 1 cm2 ） Section polished，area is
1.25cm2
试验方法 Specimen Method.
10%草酸(H2C2O4·2H2O)浸蚀，电流密度 1 A/ cm2 ，浸蚀时间 1.5 分钟后，置于 250 倍～500 倍 显微镜下观测 Etched by 10%Oxalic Acid solution, The polished specimen should be etched at 1 A/cm2 for 1.5 min.
Testing Report of Intergranular Corrosion
不锈钢晶间腐蚀e法试验时间 -回复
不锈钢晶间腐蚀e法试验时间-回复不锈钢晶间腐蚀（Intergranular Corrosion，简称IGC）是一种常见的不锈钢腐蚀形式，其影响不锈钢材料的性能和使用寿命。
e法试验是一种常用的方法，用于评估不锈钢材料中晶间腐蚀的倾向性。
本文将逐步回答关于不锈钢晶间腐蚀e法试验时间的问题。
第一步：了解不锈钢晶间腐蚀不锈钢是一种具有良好耐腐蚀性能的金属材料，主要成分为铁、铬、镍和钼。
其中的铬元素起到了抵抗腐蚀的关键作用，形成了一层致密的氧化铬膜，阻止金属进一步腐蚀。
然而，不锈钢在某些条件下仍然会发生晶间腐蚀。
晶间腐蚀是由于不均匀的晶界化学成分造成的，常见的原因包括过高的碳含量、过高的温度、长时间暴露在腐蚀介质中等。
晶间腐蚀会导致不锈钢的力学性能下降，甚至导致材料的完全失效。
第二步：了解不锈钢晶间腐蚀e法试验e法试验是一种通过浸泡不锈钢试样在特定温度下进行观察，评估不锈钢晶间腐蚀倾向性的方法。
该试验通常在酸性介质中进行，使用硫酸、硝酸等溶液进行浸泡。
试样在试验过程中会产生明显的晶间腐蚀现象，形成蚀孔等缺陷，通过观察这些缺陷的形态和数量来评估材料的晶间腐蚀倾向性。
e法试验中的关键参数包括试验温度、试验时间和试样形状等。
试验温度的选择通常是根据实际使用条件确定的，可以是室温下或高温下的特定温度。
试验时间主要取决于试样材料的晶粒尺寸和腐蚀介质的侵蚀性，一般来说，试验时间越长，观察到的晶间腐蚀越明显。
第三步：确定不锈钢晶间腐蚀e法试验时间确定不锈钢晶间腐蚀e法试验时间需要综合考虑多个因素。
首先，需要明确试验的目的和要求。
不同的应用场景和要求可能需要不同的试验时间。
其次，需要考虑试样材料的晶粒尺寸。
晶粒尺寸越大，晶间腐蚀现象通常就会越明显，需要相应延长试验时间。
此外，要考虑试样材料的化学成分、热处理状态等因素，因为它们也会影响晶间腐蚀倾向性。
根据经验，一般的e法试验时间为1至72小时。
具体选择试验时间时，可以进行以下步骤：1. 开展一个试验的初步方案，包括试验温度和试验时间范围。
astm262晶间腐蚀试验
标准编号：ASTM A262-2010 标准类型：Practice发布单位：US-ASTM发布日期：2010年1月1日状态：现行中国标准分类号：H25 冶金金属理化性能实验方法关键词：奥氏体不锈钢硫酸铜腐蚀检验腐蚀剂结构硫酸铁粒间腐蚀硝酸草酸奥氏体不锈钢铸件分类铜-硫酸铜-硫酸试验缺口钢沟渠结构端面晶粒点蚀硫酸铁-硫酸试验晶粒凹点枝晶间沟渠晶间腐蚀(IGA)金相结构金属/合金微观组织检查硝酸/氢氟酸试验草酸浸蚀试验样品制备(试验用)不锈钢(腐蚀试验)梯级结构钢结构分析/应用灵敏性钢外观检查焊接钢材料/应用austenitic stainless steelcopper sulfatecorrosion testingetchstructuresferric sulfateintergranular corrosionnitric acidoxalic acidAustenitic stainless steel castingsClassificationCopper-copper sulfate-sulfuric acid testDiscontinuities--steelDitch structureEnd grain pittingFerric sulfate-sulfuric acid testGrain pitsInterdendritic ditchesIntergranular attack (IGA)Metallurgical structureMicroscopic examination--metals/alloysNitricacid/hydrofluoric acid testOxalic acid etch testSpecimen preparation (for testing)--metals/alloysStainless steel (corrosion testing)Step structureStructural。