ASTM G34 循環(huán)濕熱腐蝕的試驗方法

ASTM G34發(fā)行信息

標準號ASTM G34-2001(2007)

中文名 2XXX和7XXX系列鋁合金剝落腐蝕敏感性的試驗方法(EXCO 試驗)

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

發(fā)布日期2001

實施日期

廢止日期無

中國標準分類號H25

國際標準分類號77.120.10 (Aluminium and aluminium alloys)

發(fā)布單位US-ASTM

ASTM G34適用范圍

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.

本試驗方法最初是為研究和開發(fā)目的而開發(fā)的；但是，在特定材料規(guī)范中，適用于評估生產(chǎn)材料時，可參考該標準（參考第14節(jié)“精度和偏差”）。

使用本試驗方法可有效預測這些合金在各種類型的戶外服務中，尤其是在海洋和工業(yè)環(huán)境中的剝落腐蝕行為。4試驗溶液具有很強的腐蝕性，代表了更嚴重的環(huán)境服務類型，當然，不包括：，不太可能在自然環(huán)境中遇到的特殊化學品。

剝落等級是任意選擇的，以說明本試驗中抗剝落的范圍很廣。然而，對于給定合金，EXCO試驗額定值與實際使用條件之間是否存在相關性仍有待確定。鋁合金剝落腐蝕任務組（G01.05.02.08）正在進行的一項活動是為此目的維持戶外暴露試驗。例如，據(jù)報告5，在48小時EXCO試驗中，評級為EA或P的Al-Zn-Mg-Cu合金樣品在暴露于海岸大氣的六至九年期間未出現(xiàn)超過微量的早期剝落（EA），而在大多數(shù)情況下，評級為ED的材料在海岸大氣中一年內出現(xiàn)嚴重剝落。隨著室外試驗的延長，預計還會有更多的比較。