alum weld help

[OscarJr]

we made it land here just for you oscar

Anyone know of a home DIY shot-peening outfit that isn't ridiculously expensive?

[old jupiter]

For those who haven't come upon this yet, another slant on stress-relieving, from the late great engine man, Joe Mondello:

https://www.mondello.com/page23.php

[snowbird]

Excellent. I love reading "white papers" with empirical data.

we made it land here just for you oscar

[OscarJr]

Here is a very promising article that "Snowbird" was kind enough to point me towards

"The fatigue strength of longitudinal butt welds in aluminum plates can be increased significantly by peening the weld and the heat affected zone."

http://www.shotpeener.com/library/pdf/1963002.pdf

And more here if you care to dig

http://www.shotpeener.com/library/index.php

.

Excellent. I love reading "white papers" with empirical data.

[H80N]

Holy cow...

Yep.... sometimes a thread will just take of in a different but still useful direction...

[ryanjones2150]

alum weld help

Holy cow...

[H80N]

Here is a very promising article that "Snowbird" was kind enough to point me towards

"The fatigue strength of longitudinal butt welds in aluminum plates can be increased significantly by peening the weld and the heat affected zone."

http://www.shotpeener.com/library/pdf/1963002.pdf

And more here if you care to dig

http://www.shotpeener.com/library/index.php

.

[H80N]

Another Approach...?? Maybe..??

Is it possible/practical to achieve strain hardening of aluminum using shot blasting..??

it is used on some other metals... is there an application here...??

[H80N]

natural age hardening annealed aluminum

If you do an internet search on

"natural age hardening annealed aluminum"

you will find a wealth of knowledge

https://search.yahoo.com/search;_ylt=AwrBT9xaFNtV7a8AypxXNyoA;_ylc=X1MDMjc2NjY3OQRfcgMyBGZyA3lmcC10LTcwMC1zBGdwcmlkA2F0cjhHck5QVHYydkQzbC5jWGRMcUEEbl9yc2x0AzAEbl9zdWdnAzAEb3JpZ2luA3NlYXJjaC55YWhvby5jb20EcG9zAzAEcHFzdHIDBHBxc3RybAMEcXN0cmwDMzkEcXVlcnkDbmF0dXJhbCBhZ2UgaGFyZGVuaW5nIGFubmVhbGVkIGFsdW1pbnVtBHRfc3RtcAMxNDQwNDIxOTAz?p=natural+age+hardening+annealed+aluminum&fr2=sb-top-search&fr=yfp-t-700-s&fp=1

Here is a short overview.. though still pretty complex..

Age Hardening

After solution treatment and quenching, hardening is achieved either at room temperature (natural ageing) or with a precipitation heat treatment (artificial ageing). In some alloys sufficient precipitation occurs in a few days at room temperature to yield stable products with properties that are adequate for many applications. These alloys sometimes are precipitation heat treated to provide increased strength and hardness in wrought and cast alloys. Other alloys with slow precipitation reactions at room temperature are always precipitation heat treated before being used.
In some alloys, notably those of the 2xxx series, cold working of freshly quenched materials greatly increases its response to later precipitation treatment. Mills take advantage of this phenomenon by applying a controlled amount of rolling (sheet and plate) or stretching (extrusion, bar and plate) to produce higher mechanical properties. However, if the higher properties are used in design, reheat treatment must be avoided.
Where natural ageing is carried out the time may vary from around 5 days for the 2xxx series alloys to around 30 days for other alloys. The 6xxx and 7xxx series alloys are considerably less stable at room temperature and continue to exhibit changes in mechanical properties for many years. With some alloys, natural ageing may be suppressed or delayed for several days by refrigeration at -18°C or lower. It is common practice to complete forming, straightening and coining before ageing changes material properties appreciably. Conventional practice allows for refrigeration of alloys 2014 - T4 rivets to maintain good driving characteristics.
The artificial ageing or precipitation heat treatments are low temperature long time processes. Temperatures range from 115-200°C and times from 5-48 hours. As with solution treatment accurate temperature control and spatial variation temperatures are critical to the process and generally temperatures should be held to a range of ±7°C.
The change of time-temperature parameters for precipitation treatment should receive careful consideration. Larger particles or precipitates result from longer times and higher temperatures. The objective is to select the cycle that produces the optimum precipitate size and distribution pattern. Unfortunately, the cycle required to maximise one property, such as tensile strength, is usually different from that required to maximise others such as yield strength and corrosion resistance. Consequently, the cycles used represent compromises that provide the best combination of properties.

Source: Materials World, Vol. 12, No. 3, pp. 37-38, March 2004. http://www.azom.com/article.aspx?ArticleID=2540

[H80N]

Again, I'm a little vague about those facts, I understand expensive fabrications like Zancanato Cycles are heat treated to regain temper. I believe it is impractical for amateur fabricators like me to consider. Age hardening sounds pretty passive, I like that. Tell me more.

Willie

I am by no means an expert on the subject either.. but I do understand that Aluminum Alloys 355, 356, 6061, 6063, 7075, and 2024 can be age hardened.

Here is a short thread from WW that gives us some info

http://weldingweb.com/showthread.php?248021-how-to-reharden-aluminum-after-annealing-it

Maybe somebody with more comprehensive knowledge of the subject can chime in...

AND... we have managed to wander way off topic yet again..

But it is a very interesting and probably useful offshoot....
(is an observation...NOT complaint....)

Here is a link to very much more comprehensive Aluminum info...
the water gets deep very fast...
Aluminum Alloy Property Data from Matweb

http://matweb.com/reference/aluminum.aspx

[WillieB]

Willie

are we discounting the option of heat treating the whole welded assy and that some alloys like 6061 will age harden... regaining some of it's strength...??

Again, I'm a little vague about those facts, I understand expensive fabrications like Zancanato Cycles are heat treated to regain temper. I believe it is impractical for amateur fabricators like me to consider. Age hardening sounds pretty passive, I like that. Tell me more.

[H80N]

.......
Perhaps because of the nearby annealing of aluminum, the added strength of 4943 filler is of little value.

Willie

are we discounting the option of heat treating the whole welded assy and that some alloys like 6061 will age harden... regaining some of it's strength...??

[WillieB]

Steel building or bridge frames have joints subject to motion fastened with elaborate fabricated intersections pinned with bolts, or rivets. This offers the sawhorse effect moving the stress away from the weld.

[WillieB]

I haven't your level of knowledge in engineering. My point was that a bit of softness at the joint of a truss isn't necessarily destroying the strength of a well designed object.

The simplest of tables; a top with four legs welded to it will likely bend because the weld adjacent metal is annealed. Placing a diagonal brace of even 6" length will dramatically strengthen the table. Now the annealing at the weld is less a problem.

A bicycle, using a truss design isn't objectionably weakened by annealing near the weld.

Perhaps because of the nearby annealing of aluminum, the added strength of 4943 filler is of little value.

[OscarJr]

Way too complex a graph for me to understand, I suspect you intended it to be. I do know a plank supported on two sawhorses one at each end, loaded with bricks until overloaded to failure, won't break at one end. It'll break near the middle.

No, it was not intended to be "too complex to understand". Just a visual representation of the bullet'ed statements regarding stress and deflection.

A plank on two sawhorses is a different scenario where a beam is simply supported from underneath on both ends, not with rigidly fixed ends. That scenario does not apply to a beam with rigidly fixed ends, which is what diagonal bracing would be. Correct, a plank on sawhorses will break in the middle with enough load, so long as it has a constant cross-section:



Rigidly clamp the ends, and it changes everything. Which brings us back to exactly what 'diagonal bracing" would be considered. The member acting as a diagonal-brace is a beam with rigidly fixed ends, hence the "plank supported on sawhorses" analogy does not apply.