ASTM G34 循环湿热腐蚀的试验方法

ASTM G34发行信息

标准号ASTM G34-2001(2007)

中文名 2XXX和7XXX系列铝合金剥落腐蚀敏感性的试验方法(EXCO 试验)

英文名Standard Test Method for Exfoliation Corrosion Susceptibility in 2XXX and 7XXX Series Aluminum Alloys (EXCO Test)

发布日期2001

实施日期

废止日期无

中国标准分类号H25

国际标准分类号77.120.10 (Aluminium and aluminium alloys)

发布单位US-ASTM

ASTM G34适用范围

This test method was originally developed for research and development purposes; however, it is referenced, in specific material specifications, as applicable for evaluating production material (refer to Section 14 on Precision and Bias).

Use of this test method provides a useful prediction of the exfoliation corrosion behavior of these alloys in various types of outdoor service, especially in marine and industrial environments.4 The test solution is very corrosive and represents the more severe types of environmental service, excluding, of course, unusual chemicals not likely to be encountered in natural environments.

The exfoliation ratings were arbitrarily chosen to illustrate a wide range in resistance to exfoliation in this test. However, it remains to be determined whether correlations can be established between EXCO test ratings and realistic service conditions for a given alloy. It is an ongoing activity of the Task Group on Exfoliation Corrosion of Aluminum Alloys (G01.05.02.08) to maintain outdoor exposure tests for this purpose. For example, it has been reported5 that samples of Al-Zn-Mg-Cu alloys rated EA or P in a 48-h EXCO test did not develop more than a slight amount of incipient exfoliation (EA) during six- to nine-year exposures to seacoast atmospheres, whereas, ED rated materials in most cases developed severe exfoliation within a year in the seacoast atmosphere. It is anticipated that additional comparisons will become available as the outdoor tests are extended.

1.1 This test method covers a procedure for constant immersion exfoliation corrosion (EXCO) testing of high-strength 2XXX and 7XXX series aluminum alloys.

Note 18212;This test method was originally developed for research and development purposes; however, it is referenced, in specific material specifications, as applicable for evaluating production material (refer to Section 14 on Precision and Bias).

1.2 This test method applies to all wrought products such as sheet, plate, extrusions, and forgings produced from conventional ingot metallurgy process.

1.3 This test method can be used with any form of specimen or part that can be immersed in the test solution.

1.4 This 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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

本试验方法最初是为研究和开发目的而开发的；但是，在特定材料规范中，适用于评估生产材料时，可参考该标准（参考第14节“精度和偏差”）。

使用本试验方法可有效预测这些合金在各种类型的户外服务中，尤其是在海洋和工业环境中的剥落腐蚀行为。4试验溶液具有很强的腐蚀性，代表了更严重的环境服务类型，当然，不包括：，不太可能在自然环境中遇到的特殊化学品。

剥落等级是任意选择的，以说明本试验中抗剥落的范围很广。然而，对于给定合金，EXCO试验额定值与实际使用条件之间是否存在相关性仍有待确定。铝合金剥落腐蚀任务组（G01.05.02.08）正在进行的一项活动是为此目的维持户外暴露试验。例如，据报告5，在48小时EXCO试验中，评级为EA或P的Al-Zn-Mg-Cu合金样品在暴露于海岸大气的六至九年期间未出现超过微量的早期剥落（EA），而在大多数情况下，评级为ED的材料在海岸大气中一年内出现严重剥落。随着室外试验的延长，预计还会有更多的比较。