Tuesday, June 2, 2020

Cold Weld is considered key to fix Hydroform Resistance Weld Seam crack: Belzona Cold Weld Structural Repair Approach?

Fundamentally, the weld itself can cause distortion of the substrate, due to heat. More commonly known as HAZ (Heat Affected Zones), the intense process of heating and subsequent cooling of the substrate can generate weaknesses in the metal and limit the structural integrity at the weld point. In certain applications the metal must undergo stress relief to ensure that the risk of subsequent changes to the metal is minimised.
 https://blog.belzona.com/embrace-the-cold-cold-bonding-vs-hot-work/

So this stuff has the same PSI as JB Weld ... yet

Belzona how to playlist

So a unibody is just stitch welded - a spot weld every inch - on the seam - vid

So the local weld shop took another look for me and said JB Weld would trap moisture - so don't do it. The weld seam crack is at the gusset - for the transmission - so it should be ok for now. Just keep doing rust treatment - converter and inhibitor. Phosphoric acid, internal spray on the tube frame - and the cosmoline RP-342.

 thanks - I went back this am and talked to the boss. So I'm just gonna do rust treatment - I just ordered a gallon of 85% concentration phosphoric acid. I also got Eastman internal frame spray. I got RP-342 in the mail - should be here soon. So - the boss is claiming that the resistance weld seam cracked due to internal rust and that it will keep spreading due to rust. He said that since it's to a gusset cross piece (to the transmission) then it should stop spreading and not be so bad. He said NOT to use any JB weld as that will trap moisture and make the rust worse. I asked him about drilling holes to stop the crack spreading - he said not in the seam. I said maybe high frequency arc weld - since it's hydroformed tube. He does TIG welding - so he knows what that is. No - he didn't think that would fix it. So the patch put in was hard to reach - so yeah - they hammered on it a lot. I think the seam crack was from all the hammering - since hydroform is lighter steel and can't handle torsion. But there is a rust hole right next to that seam crack - so I'm sure it's rust also.

So I'm just gonna go with what the boss says - he thinks if I rust treat it then it should hold up for a few years - my goal is five years. This is Minnesota - so the salt just eats up the cars here. Yeah thanks for the feedback. I then saw that on a unibody - the seam will just be stitch welded - and so every inch. This is a two inch crack - but otherwise it's not a stitch weld. So there is debate about chassis flex for more safety for crunch zones - versus the stiffness. Anyway - so I'll just treat it and keep an eye on it. Thanks again. I think with that plate above - that will absorb stress and maintain strength - and with converting rust internally with phosphoric acid and Eastwood - then that should stop rust spreading. Also with the cosmoline.

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