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  1. #1
    Vern Smith is offline Aluminum
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    Default Information on 7075 and 7071 aluminum

    I would appreciate it if anyone can shed some light on the differences between 7075 T6 and 7071 T6 aluminum. The Internet is full of people who sell or use 7071 but could not find any technical data.

    My use would be sheet stock, probably .125 thick to be cut into strips and used as a spring. I would need to put some gentle bends in it so that would be a factor in selection.

    Vern

  2. #2
    JP Machining is online now Hot Rolled
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    I think you mean 6061 not 7071.

    7075 has almost 2x the strength of 6061 and typically costs 2x as much as well. 7075 machines nicer as the the chips are harder and break easier compared to 6061 which has a tendency to be a bit gummy.

    Just go to www.matweb.com and search the two types and you will find all the strength numbers and everything else you didn't think mattered.

  3. #3
    metlmunchr is offline Diamond
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    I agree with JP that its likely there's no such animal as 7071 aluminum. If you look closely at the web references to 7071, it quickly becomes aparent that 90+% of them are written by people who wouldn't know the difference between aluminum foil and an inconel forging.

    FWIW, aluminum of any alloy isn't a good choice for a spring unless there's some factor that precludes the use of any other material. Fatigue is the ever present problem in predictable life of cyclic loaded aluminum parts, and springs are all about fatigue life above all else. If you just need corrosion resistance, SS spring stock or even Titanium sheet would make far superior springs.

  4. #4
    Matt@RFR is online now Stainless
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    No such thing as 7071 aluminum according to www.matweb.com . Go there and search for your materials to answer your original question.

  5. #5
    Vern Smith is offline Aluminum
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    I appreciate the information. I guess I now know why all the information I could find was from people who sold or used 7071 and no technical specifications.

    Where would I find small quantities of titanium sheet? Can it be sheared with normal sheet metal shop equipment? Would you use standard radius breaks to bend it? What's it's general cost relationship to say 6061 aluminum?

    Vern

  6. #6
    Daave is offline Plastic
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    Vern,

    There has been some experimenting done on AL 7071-TS but nothing that has ever hit the market to my knowledge. In 1996 there was an experiment done up in the UK with a few sheets of AL 7071-TS to test for Residual stresses in aluminium alloy. The alloy itself contains 4.5% zinc and 2.5% magnesium. As far as purchasing it I doubt you'll find it from the regular avenues.

    -Daave

  7. #7
    morsetaper2 is online now Titanium
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    Mcmaster-carr has a bit about aluminum here. Likely more stuff on their website...

    http://www.mcmaster.com/param/html/aluminum/default.htm

  8. #8
    Hdpg is offline Stainless
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    Quote Originally Posted by Vern Smith View Post
    ....My use would be sheet stock, probably .125 thick to be cut into strips and used as a spring. I would need to put some gentle bends in it so that would be a factor in selection.

    Vern
    You are a bit contradictory here; any aluminum alloy at a temper high enough that it could serve as a spring is not going to bend very cheerfully.

    But it is a moot point; aluminum in any form is not suitable for a spring because it does not have a lower fatigue limit. Any aluminum alloy experiencing a cyclic load will eventually fail due to fatigue; for lightly loaded parts that are elastically deformed a very small amount eventually can be hundreds of thousands of cycles, heavily loaded parts undergoing significant elastic deformation may fail in only tens of cycles.

  9. #9
    Matt@RFR is online now Stainless
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    Quote Originally Posted by Hdpg View Post
    Any aluminum alloy experiencing a cyclic load will eventually fail due to fatigue;
    If Vern followed through with his idea, then he should have some data to support this.

    This thread is 1.5 years old.

  10. #10
    Hdpg is offline Stainless
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    Quote Originally Posted by Matt@RFR View Post
    .....This thread is 1.5 years old.
    Silly me normally I remember to check dates.

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