7004 T1 and T5 alloy after 25 yrs near welds

[trainguy]

All,

This is a follow up of a question I asked on Struct Eng Other Topics, with more specifics.

I'd like to know the yield strength of 7004 T1 and 7004 T5 alloys, very close to a weld, 25 years after the weld was made.

Environment: Exposed underframe of a passenger train in Canada.

Is the yield strength still the "as-welded" value of 24 ksi or is it closer to the T1 and T5 values (30 and 46 ksi respectively)?

Thanks.

tg

 

[EdStainless]

You would need to do some hardness testing to see how much aging has taken place.
I would expect some, but it might be rather small. It will depend on how the welds were made originally.

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Plymouth Tube

 

[metengr]

Most likely for these materials, the heat affected zones would continue to age only days after welding. I would say beyond several weeks or a month, there would be no further change. So, I would expect the YS/TS to have increased in the base metal HAZ but still remain closer to the as-welded value.

 

[trainguy]

Thanks guys.

tg