|
|
Hi there,I'm working on a coupler that goes between two pressure vessels. The part was supposed to be fluted so it could easily be turned. It's 1.75" OD Grade9 tube. The machinist messed up and instead of putting the flute .010 into the surface of the tube, he put it .050!!! This is a serious problem for me, because the part has a lot of machining on it and new tubing is 4 months out. So I'm stuck with this for now. The factor of saftey with the deep flute is 1.5 out of a 3.0 I wanted to hold this project to.The picture shows the flute but nothing else. I was able to correct the depth of all the other flutes, but the first one is and issue now.I need to know filling in this flute with weld is going to solve my now too shallow wall thickness issue. Obviously it's possible, what I don't know is if titanium will take to this. I could see problems like the entire area becoming too brittle, or something like that.Any welders have experience with structural Ti? Is it possible to fill this flute in and in that area regain the strength of the thicker wall? Any tips?
Reply:Can't really read your post...
Reply:1-For image posting, 800 x 600 pixels and a .jpg size of 150 kb is max.---otherwise they get chopped off, as you notice. I trimmed and re-sized your images, below.2-IMHO-this would be a micro welding task, however:-expect some bowing of the sleeve from the contraction stress of the weld,which i'd suspect would trash the part.-machining of the weld, getting good blending, etc,--due to the aboveand I have no idea as to how the Ti weld would react to machining-but it mightnot be at all like the parent material.-then there's the question of welding stress imparted to a pressure rated parthttp://weldingweb.com/attachment.php...1&d=1304218656http://weldingweb.com/attachment.php...1&d=1304218670 Attached ImagesBlackbird
Reply:Just going on hear say, but the only person I've known that did any welding on Ti did so in a climate controlled room and wore a breathing apparatus. Maybe someone else knows here more about it.
Reply:Okay, to weld Ti successfully, your gas coverage is of premium importance, as is your heat input. While getting a rainbow on an exhaust system will be fine, for your application, you won't want to see any color besides straw with only the slightest hint of bluing. Any more, you have gotten it too hot. In a true pressure vessel system, I don't think you are going to add the strength back in with the wall thickness, as you will have an awful long HAZ to deal with. COULD YOU???? Sure. But I would x ray that thing after welding, and I would check into normalizing of the part, and then heat treatment to required hardness. I don't see this repair getting signed off by a QC inspector very easily. Maybe prepare the shop for buying a new part.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Good notes.The OD tolerance isn't critical, so if it swells/moves/bulges/etc a little bit I can still work around that. There are of course parts not shown here. It's getting welded to two other pieces anyhow and those are the only parts that have to be "true". I guess I just need to know if adding the metal back into the flute is A. going to add strength back in B. Not cause some complication like actually making the part weaker (brittle or otherwise). I'm looking into stress relieving and/or solution heat treating (water quelch) and I write this. One issue with that is I'm not sure where I could have that done as anything in Ti over 800F requires a zero oxygen environment.
Reply:Originally Posted by jnzGood notes.The OD tolerance isn't critical, so if it swells/moves/bulges/etc a little bit I can still work around that. There are of course parts not shown here. It's getting welded to two other pieces anyhow and those are the only parts that have to be "true". I guess I just need to know if adding the metal back into the flute is A. going to add strength back in B. Not cause some complication like actually making the part weaker (brittle or otherwise). I'm looking into stress relieving and/or solution heat treating (water quelch) and I write this. One issue with that is I'm not sure where I could have that done as anything in Ti over 800F requires a zero oxygen environment.
Reply:You are better off starting from a fresh piece IMO. The wall that gets welded is going to bow, terribly, causing the tube to become egg shaped. You have to replace 50% of your stock (in the groove). That is a lot of stress for a small piece like that, especially for titanium. You stated that it was "structural" titanium, which would make me think that you have a certain amount of strength needed. (Vs, a light weight need).Dock the machinist the price of the stock, he'll think before pressing the "go" button next time. He may even do a steel sample piece first for proof out & prevent a mess like that next time.. Steel is cheapBuy American, or don't whine when you end up on the bread line.
Reply:Originally Posted by WeldingMachineYou are better off starting from a fresh piece IMO. The wall that gets welded is going to bow, terribly, causing the tube to become egg shaped. You have to replace 50% of your stock (in the groove). That is a lot of stress for a small piece like that, especially for titanium. You stated that it was "structural" titanium, which would make me think that you have a certain amount of strength needed. (Vs, a light weight need).Dock the machinist the price of the stock, he'll think before pressing the "go" button next time. He may even do a steel sample piece first for proof out & prevent a mess like that next time.. Steel is cheap
Reply:Fill it with JB weld itll be fine.http://www.leap.cc/cms/index.php
Reply:Simple answer is yes, it can be done successfully. But it is going to take someone with experience with these kind of repairs.If you want to get it fixed, find a mold/tool&die repair company that works with Ti and consult with them, don't base a critical repair procedure off of what you hear from the internet.Have we all gone mad?
Reply:McMaster-Carr offers solid gr. 5 round bar 1.5" +/.006, 1' length, in stock,if saving time and money is needed.1 1/2"±0.006"89055K431$208.51Blackbird
Reply:My boss has done titanium and I guess it needs to be done within an enclosed chamber. Mind you, you only need a chamber around what you are working on. I don't have hands on experience with Titanium myself, I've heard that it welds like glass, but I know the stuff is bloody well expensive!
Reply:Have it laser welded. That would not distort your part at all. |
|
发表于 2021-9-1 00:15:54