Quote:
Originally Posted by ToddF
From the wiki on 6061 aluminum:
"6061 is highly weldable, for example using tungsten inert gas welding (TIG) or metal inert gas welding (MIG). Typically, after welding, the properties near the weld are those of 6061-O, a loss of strength of around 80%. The material can be re-heat-treated to restore -T4 or -T6 temper for the whole piece. After welding, the material can naturally age and restore some of its strength as well. Nevertheless, the Alcoa Structural Handbook recommends the design strength of the material adjacent to the weld to be taken as 11,000 psi without proper heat treatment after the weld."
That compares to 35ksi yield strength of properly heat treated 6061-T6.
Teams that use welded aluminum construction need to realize that your welded joints are now incredibly weak. And that's if the welding has been done with perfect technique (certified welder with years of experience). High school grade workmanship will be way worse. |
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Been there, seen that a million times (after welding of that particular frame joint in your pic...It certainly appears to me that much more than 50% of the weld was then quite overly ground away, seeing that the appearance of the lack of any weld bead is also present). It is a ton of work I know, and the same issues happened to our team during Rebound Rumble (we played in the finals, lost, then rebagged a known very injured bot after our first regional, and it saw us stripping our bot completely down in the pits, to a very custom and powder coated dual side intake frame, at our second regional in Las Vegas, because every single weld broke that there was to break, between (many slightly over ground welds), a lot of very active defense, and that nasty floor beam we crossed much too often. That of course, led to many other bugs after the welding was done too, and that robot reassembled in a short period of time. That bot just wasn't quite right until Q time was nearly finished (it was by then, but we had not shown the necessary reliability to that point that another team would/could trust)....Wasn't a good year for us needless to say. I hope you fare much better in your case.
Not a weld on this years bot BTW, as we knew it was going to be a very defensive hard hitting game. Though last years bot was for us.....It lasted. (And that one incident caused us to learn to go much more modular in the future).
You have one thing going for you...At least the carry in has luckily been increased to 45 lbs....That 50% increase should get you there. (Well that and a good pit crew I certainly hope!)
Good Luck! (Weld clean, and leave the beads please).