6082 forming

Discussion in 'Metal Boat Building' started by Guest62110524, Jun 20, 2009.

  1. Guest62110524

    Guest62110524 Previous Member

    usually I form frames 6061 t6
    I am abt to order a shipment 6082 T6
    Research show me, that this has lower formability
    I am not forming as tight bilge like curves but gradual caprails and belting sec tions
    I remember once taking a shipment of brittle flat bar in 6061, for longtitudinals in a mussel boat and when we started to form they cracked, as it was the mill was local and they replaced, , liars said it was mill cert stuff!!
    So has anyone hands on formed this metal?
    Preciate it
    the caprail is solid as is belting and if anyone can use the sections please contact as the darned dies are not cheap
     
    Last edited: Jun 21, 2010
  2. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    6061 T6 and 6082 T6 have pretty much the same elgoation in the less than 5mm and between 5~10mm range.
    Used 6082 for over 15 years, no problems.
    I personally don't recommend 6061 owing to its higher copper content and can lead to poor corrosion.

    The image is very small, but the belting die looks like one of mine from years ago!
     
  3. Guest62110524

    Guest62110524 Previous Member

    yes BUT will it do this, I have built these for ages in 6061 T6 and never had corrosion issues
    Also many commercial fishing boats Will it form like this without cracking
     
    Last edited: Jun 21, 2010
  4. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    As i posted, the elongation in the same temper T6 are the same, or slightly different (1%) deepening which mill you get it from and the standards they use. This means the ductility is the same. The min bend radii etc are the same for both. The fracture stress is slightly higher as is the yield stress in 6082. This is the only mechanical property that may affect they way you form. As with all forming depends how you do it, ie the method and 'tools'. However, all in all, in terms of forming you should not notice any difference.

    If your method of forming you find it a little more difficult, for whatever reason, select the T4 temper, this has more ductility than T6. (True for both alloys).

    6061 has 3 times as much copper content as 6082. This is the reason why it was developed in the early 90s, as 6061 (plenty about owing to the aircraft industry so everyone just used this), exhibts poor corrosion in certain conditions, owing to its higher copper content. LR and DNV for example, wont allow it below the waterline or being 'exposed' to sea water. LR requires proof of previous applications that show no serious side effects too.
     
  5. Guest62110524

    Guest62110524 Previous Member

    thanks BUT you are wrong on several counts, 6061 was used in the 70, 80,s 90,s but all of us , (you meant 6082 in 90,s? I spose, I also built the smallest LR yacht in NZ, with that metal never any problems
    Caper AUK000168 LR, Reg NZ ship 875880
     
  6. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    yes referring to 6082 being a new alloy developed in the early 90s as a proper 'marine grade' alloy.

    But by saying "you've never had any problem with 6061" is somewhat meaningless. That is just anecdotal. There is plenty of evidence to the contrary which is why as noted above, Class no longer allow 6061 below the waterline and in LR's case, at all. Why?? not because i say so...in service experience of the alloy (during surveys and insurance claims) and the use of it in the wrong conditions owing to ignorance or negligence.

    Just because you have never seen it, does not mean it there is no problem. I have seen such effects myself (quiet costly to repair it was too). The fact Class have amended their rules form the 1970s to the 00s is evidence of this, as well as the development of 6082.

    The vessels i design are typically operate for 3000~3500hours a year, year in year out, often in harsh environments. Any weakness is very quickly exposed. This cannot be said for luxury market, where similar conditions takes many more years to manifest themselves into a problem; unless the boat is constantly sailing around the world year in year out without stopping; that's what is required as a comparison of 'usage'. Otherwise it is seen as "ahh..just getting old or normal wear and tear" owing to being 20 or 30 years old!
     
  7. Guest62110524

    Guest62110524 Previous Member

    meaningless?
    You will notice I back up all I say with pics and numbers
    You can say anything you like here, so far I have never seen anything you designed or built, , or owners or whoever you have worked for, despite asking? any reasons for this
     
  8. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    Ahh..that same old chestnut, yawn!. Ignoring the fact that Class no longer allow 6061 for the reasons cited is of course meaningless! But of course Class's dismissal is not enough evidence for you, in which case nothing is, as you have made up your own mind and wont budge, regardless of any 'evidence'.

    As I have noted to you before, but shall iterate again, since you seem to have forgotten.

    For those who consistently bleats "show me your company, show me your boats, show me your numbers ad nauseum ", do not practice what you preach. In addition to the "pictures" you show, they do not demonstrate any form of "quality" at all, it is just a picture of someone or something being done. Just like those who bleat, “show me your numbers..” this just means someone does not understand or been taught the theory because they use a computer program to do all their calculations, and as such require “numbers” to answer questions properly. A program cannot give you the reasons why,.. just numbers!

    So, if I were to say I have just 1 boat designed/built in my ‘gallery’, you would feel instantly better in your knowledge and expertise compared to mine. Yet, if I said I have 100 boats designed/built, you would perhaps be more humble or acquiescent. All this demonstrates is arrogance. It is the behaviour of someone wanting or needing superiority over others, as well as constant ‘pats’ on the back.

    If you are unable to answer a Q effectively, you resort to an attack on the questioner, not the question at hand (since you have ignored Class's advice because it doesn't sit with your opinion).

    In doing so, just exposes arrogance. Since whether the Q comes from a newbie or a well-seasoned professional, you can either answer the Q or you cannot. The person asking the question is irrelevant, only the question is relevant. Your replies may be different from someone else’s and as such become exposed to scrutiny by others. Attacking the questioner, rather than the Q or reply clearly demonstrates an unwillingness to accept someone else’s point of view which may or may not better than your own; especially if it exposes poor QA.

    The biggest problem with quality boats built in aluminium, are those fabricators who do not understand what quality means, nor keeping up with the latest developments and changes in practice.
     
    1 person likes this.
  9. Guest62110524

    Guest62110524 Previous Member

    ok suit yourself you are back on ignore, I felt sorry for you
    you can never give an honest answer
    quite frankly your claims, especially the ones abt brit MOT MOD are plainly absurd, visions in your mind, ,
    Facts, you are so fond of quoting tables, compositions, But there , we have no facts about you at all Thousands of folk pass by this board, most are upfront, you are evasive, not at all upfront, so why should anyone believe you?
    I do not and plenty of the Guts of this board do not either
    Good day to you
     
  10. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    QED

    thank you :)
     

  11. apex1

    apex1 Guest

    Stu,
    you bark up the wrong tree here.
    The fact that someone does´nt like to unveil his company or personal information does not mean he cannot provide proven facts and a deep knowledge. In this case you should have asked in Galicia for a opinion. I have some private contacts with Ad Hoc and can assure you there are few as professional around here!

    Regards
    Richard
     
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