Machining Tig welds?

admin

Can an aluminum tig weld be machined flat?I ask because I have a damaged cylinder head that needs to be tig welded on the gasket surface, and I want to make sure the repair will last and hold a good seal.Thanks in advance for any insight.
Reply:Yes, build higher than needed, then have it milled. Its a casting so I would advise to pre heat at 350 degrees, weld, then post heat at 350. Use A356, 4045, or 4043.Let it set for a few days before remachining and putting into service. Peter
Reply:Thank you for the reply and detailed answer to my question!
Reply:Originally Posted by castweldYes, build higher than needed, then have it milled. Its a casting so I would advise to pre heat at 350 degrees, weld, then post heat at 350. Use A356, 4045, or 4043.Let it set for a few days before remachining and putting into service. Peter
Reply:You let it set so the metal cools evenly preventing cracking.
Reply:Would the procedure be the same for 6061 Aluminum ?
Reply:Sounds good, another reason to post weld heat it, and then let it set is to allow it to age harden. 6061, 2024, and some of the precipitation hardening cast alloys will self age harden, (and be a lot easier to machine smooth without tearing), if you leave them for a couple of days. 6061 can be pushed to a T-4 temper with a few hours in an oven at 350 deg F. ( it will anneal if quenched from about 950deg f ).  Aluminum is the opposite of steel, you quench steel to lock the carbon into the iron and make it hard, then heat it to temper, soften, it.   You quench aluminum to lock the alloys in to keep it soft, and heat it to allow them to migrate out to the crystal slip planes to make it hard.       The self age hardening is one reason aluminum welds tend to be weak when first made, and get stronger, and more brittle sometimes, with age.past work toys; lathes,mills, drills, saws,  robots, lasers ironworker, shears, brake, press, grinders, tensile tester,  torches, tigs, migs, sticks, platten table, positioner,  plasmas , gleeble and spot. Retired June 30, 2009.
Reply:Thank you - that was an excellent explanation.