territorialmillworks Posted May 21, 2012 Share Posted May 21, 2012 at work, I tried to weld cracks on the 4x4 alum sq tubing that makes up the bed of the fire truck. The alum wouldnt puddle or flow. Had good clean surface and plenty of amps. Tried a horizontal area with out a crack thinking there might be contamination. No luck. My boss tried..same thing. Any ideas what is going on? Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted May 21, 2012 Share Posted May 21, 2012 What type of welder are you using and what were the settings? I'm thinking that the metal was not just alum but some other alloy, as possibly titanium. How thick was the 4 X 4 tubing and what happened when you did try to weld it? Did nothing happen or did it form a clump? Sorry for the questions, but it's an interesting problem. Quote Link to comment Share on other sites More sharing options...
HWHII Posted May 21, 2012 Share Posted May 21, 2012 Their is a posability the tube has a anodized coating on it. It would be what they call a mill finish and be gray in color just like aluminum. It has a higher melting temperature then the aluminum base metal. It won't flow and if you try to add filler it will just ball up on top. You can sand or grind this coating off to reveal the base metal, a wire wheel or brush will not do it. After you grind or sand it you will need to use a stainlees wire wheel or brush then to clean the weld area. Then weld it. Your weld might still be a bit dirty though. If you are using a square wave machine move you balance more to the DC+ side and this will help clean it up. Make sure you use a 5356 filler metal on it. Quote Link to comment Share on other sites More sharing options...
r smith Posted May 21, 2012 Share Posted May 21, 2012 Is there any chance it is cast rather than extruded? Quote Link to comment Share on other sites More sharing options...
territorialmillworks Posted May 21, 2012 Author Share Posted May 21, 2012 Miller syncowave180 ad. Er5356 filler rod. 3/16 wall thickness. Too soft to be titanium. Quote Link to comment Share on other sites More sharing options...
HWHII Posted May 21, 2012 Share Posted May 21, 2012 Miller syncowave180 ad. Er5356 filler rod. 3/16 wall thickness. Too soft to be titanium. I don't think 180 amp machine will get you quite there. I'm thinking 225 amps for a fillet weld on 3/16 myself. May be your machine is to small. You can try to preheat with a torch. Be careful because it's hard to judge the temp. If you have any blue layout die spray it on it and it will burn of at about 450 degrees and that should be enough preheat. Quote Link to comment Share on other sites More sharing options...
Robert Yates Posted May 21, 2012 Share Posted May 21, 2012 is it cast or Coated Quote Link to comment Share on other sites More sharing options...
Larry H Posted May 21, 2012 Share Posted May 21, 2012 one thing about aluminum is........ you need a lot of heat....if it is "CLEAN"...and hot..use a 3/32 rod, and PUSH it into the weld area....( means---, feel the rod bucking back at you, while pushing into the puddle ). If you force it....it works......try a tack with that method,..... and see if it works for you.....it should. Quote Link to comment Share on other sites More sharing options...
BIGGUNDOCTOR Posted May 22, 2012 Share Posted May 22, 2012 Is the tubing welded at other locations, or is it riveted? Some alum alloys are not easily welded. Anodizing will occur naturally (it is a form of corrosion), and is nonconductive. That is one reason why it has to be removed before welding. Have you thought of spray arcing this with a MIG? I used to do a bit ofthat in my shop, and it worked great for the applications I did like highway sign braces, and broken skegs on outboard engines. Quote Link to comment Share on other sites More sharing options...
ramsies11 Posted June 11, 2012 Share Posted June 11, 2012 might sound a little stupid but, aluminum has this wonderous quality called passivation. it is where the metals first (very small mesurement of length) turns into aluminum oxide. (aluminum rust or alo for this post). the alo makes it difficult to weld, just as rusty steel is somewhat difficult to weld. and if your welding on somthing that has had a steel on it, after long periods of time, it causes a chemical reaction between the metals which causes it to rust like ferrous metals do. somthing else that needs to be considered is aluminum is a (compared to steel) pourus metal. over time it will soak up oils and such and make it very difficult for you to weld. itd be about a half inch long weld that youd have to stop and clean and then go again because the heat causes the oils to come up. i DONT know about this, but could you attempt to braze it? Quote Link to comment Share on other sites More sharing options...
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