5356 rod

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I lost my welder to a back injury. We are welding 6061-T6 weldments for avaition ground fueling. Customer requires parts to be plated and that is why they specify using 5356 rather than 4043 rod. After welding the part must be heat treated back to the T6 condition. I can't find a welder to finish our parts because of a liabilty issue regarding using the 5356 rod. They say that the joints will become brittle and may crack in the field at any time. I'm not a welder and am trying to confirm my vendors remarks regarding this potenial cracking after heat treat. These parts must be tested under 300 hydrostatic PSI to find any leaks.  Is this correct? If we use 4043 rod it will leave a dark line on the joints that were welded and the government will not accept it. What are my options?
Reply:I think I would be looking for a independent welding engineer for some advice. A few $$$ spent now might seem pretty cheap down the road.
Reply:Originally Posted by MagichoppensI lost my welder to a back injury. We are welding 6061-T6 weldments for avaition ground fueling. Customer requires parts to be plated and that is why they specify using 5356 rather than 4043 rod. After welding the part must be heat treated back to the T6 condition. I can't find a welder to finish our parts because of a liabilty issue regarding using the 5356 rod. They say that the joints will become brittle and may crack in the field at any time. I'm not a welder and am trying to confirm my vendors remarks regarding this potenial cracking after heat treat. These parts must be tested under 300 hydrostatic PSI to find any leaks.  Is this correct? If we use 4043 rod it will leave a dark line on the joints that were welded and the government will not accept it. What are my options?
Reply:After welding the part must be heat treated back to the T6 condition. I can't find a welder to finish our parts because of a liabilty issue regarding using the 5356 rod. They say that the joints will become brittle and may crack in the field at any time.
Reply:I've welded a lot of 356T6 with 4043 and it plated fine. I know that 4043 will  leave the gray line you are refering to if you Anodize not plate. But if you are plating and not anodizing that shouldn't be an issue. Unfortunately 4043 isn't won't respond to heat treatment. And the 5356 will have mag/sil formation and hot cracking problems if the component is used/operated in an enviroment of over 150f.Take a look at Alco Tec web site and you will find a variety of alloy wire that is heatreatable and will also anodize if thats what you need.Hope this helps.ric