ASTM G34 循環(huán)濕熱腐蝕的試驗(yàn)方法

ASTM G34發(fā)行信息

標(biāo)準(zhǔn)號(hào)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(yàn)方法(EXCO 試驗(yàn))

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(shí)施日期

廢止日期無(wú)

中國(guó)標(biāo)準(zhǔn)分類號(hào)H25

國(guó)際標(biāo)準(zhǔn)分類號(hào)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(yàn)方法最初是為研究和開(kāi)發(fā)目的而開(kāi)發(fā)的；但是，在特定材料規(guī)范中，適用于評(píng)估生產(chǎn)材料時(shí)，可參考該標(biāo)準(zhǔn)（參考第14節(jié)“精度和偏差”）。

使用本試驗(yàn)方法可有效預(yù)測(cè)這些合金在各種類型的戶外服務(wù)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(yàn)溶液具有很強(qiáng)的腐蝕性，代表了更嚴(yán)重的環(huán)境服務(wù)類型，當(dāng)然，不包括：，不太可能在自然環(huán)境中遇到的特殊化學(xué)品。

剝落等級(jí)是任意選擇的，以說(shuō)明本試驗(yàn)中抗剝落的范圍很廣。然而，對(duì)于給定合金，EXCO試驗(yàn)額定值與實(shí)際使用條件之間是否存在相關(guān)性仍有待確定。鋁合金剝落腐蝕任務(wù)組（G01.05.02.08）正在進(jìn)行的一項(xiàng)活動(dòng)是為此目的維持戶外暴露試驗(yàn)。例如，據(jù)報(bào)告5，在48小時(shí)EXCO試驗(yàn)中，評(píng)級(jí)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(guò)微量的早期剝落（EA），而在大多數(shù)情況下，評(píng)級(jí)為ED的材料在海岸大氣中一年內(nèi)出現(xiàn)嚴(yán)重剝落。隨著室外試驗(yàn)的延長(zhǎng)，預(yù)計(jì)還會(huì)有更多的比較。