The second digit indicates alloy modification. If the second digit is zero. it indicates the original alloy: digits 1 through 9, which are assigned consecutively, indicate alloy modifications. The last two digits have no special significance, serving only to identify the different alloys in the group.
Experimental Alloys Experimental alloys are designated according to the four digit system, but they are prefixed by the letter X. The prefix is dropped when the alloy becomes standard. During development, and before they are designated as experimental, new alloys are identified by serial numbers assigned by their originators. Use of the serial number is discontinued when the X number is assigned.
1Based on 500000.000 cycles of completely reversed stress using the R. R. Moore-type of machine and specimen.
2张力和压缩模量的平均值。压缩模量比张力模量大约2％。
3Ratings A through E are relative ratings in decreasing order of merit, based on exposures to sodium chloride solution by intermittent spraying or immersion. Alloys with A and B ratings can be used in industrial and seacoast atmospheres without protection. Alloys with C, D and E ratings generally should be protected at least on faying surfaces.
4Stress-corrosion cracking ratings are based on service experience and on laboratory tests of specimens exposed to the 3.5% sodium chloride alternate immersion test.
5评分a至d的可加工性（冷）和可加工性的a至e是优异顺序下降的相对评分。
6评分A至D的可焊性和闪亮性是相对评分。
7A =通常通过所有商业程序和方法焊接。 B =具有特殊技术或特定应用的焊接，这些应用程序证明初步试验或测试以开发焊接程序和焊接性能。 c =由于对腐蚀和机械性能的抗裂纹敏感性或损失而有限的可焊性。
8A =通常通过所有商业程序和方法焊接。 B =具有特殊技术或特定应用的焊接，这些应用程序证明初步试验或测试以开发焊接程序和焊接性能。 c =由于对腐蚀和机械性能的抗裂纹敏感性或损失而有限的可焊性。
9A =通常通过所有商业程序和方法焊接。 B =具有特殊技术或特定应用的焊接，这些应用程序证明初步试验或测试以开发焊接程序和焊接性能。 c =由于对腐蚀和机械性能的抗裂纹敏感性或损失而有限的可焊性。
