any usefull low-buck (prefferably no-buck) NDT for welded iron?

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hey guys, i just welded an arm which holds a cutter arm onto an old lawnmower. it is made of iron and i would like to know if there are any ways to test the integrity of the weld. the piece isnt large, it was around 1/4"-3/8ths" thick. i used 309 rod, preheated (just took the "chill" off the material), made small passes and between passes i wrapped the piece with my gloves and covered with the jacket to try and slow the cooling (when it wasnt hot to the touch i cleaned the area and made my next pass) while it was cooling i tapped the surrounding areas with a hammer. the last step after some cleanup is to weld a piece of 1/8 steel plate to help strengthen the area.ok thats the background on what i did. my background is basically a hobby welder, i work in a small-engine shop and i get to do the welding. however this is the first time ive tried welding iron, while im pleased with the looks of what ive done. i want to know if there are any pheasable ways for me to test the integrity of the weld. the customer understands that its a difficult procedure, and i cant garantee that i can do it.if there are any ways beyond "put it in the field and find out" i would appreciate them, as the machine is in for a complete tune up and it would be quite wastefull to tune it up only to have it fall apart this year. thanks guysJimoh yeah, if it wasnt for this site i wouldnt have even bothered trying to weld iron L lol L , im here everyday at work and appreciate everyones advice (even if its to other peoples questions), and i learn alot here. thanks guys for all that.
Reply:sure enough, i just looked at the piece for the first time since welding it, and there is a transverse crack on one of the sides. guess i didnt need special testing spells to know how i did. lol so im going to grind it completely out, preheat and try again. any ideas, comments, or suggestions? heck, just post "hiya have fun" lol anything
Reply:Hiya! Have fun! Re-work sucks!
Reply:i knew someone wouldnt resist "hiya have fun" lol
Reply:If is is REALLY  iron, (CAST IRON) stainless is the worst to use , S.S. is TOO hard ; it doesn't give. instead, use high nickle rod, for cast or cast to steel. its soft & ductile. or if you can scrounge somewhere some rod for monel (good luck !) thats good too. An apprentice teacher of mine , back in the day (1965) told me "if you have to weld something , & don't have a clue what metals you're welding , try 8n12"   (a bi-metallic rod) but, that stuff really  costs .
Reply:Peen the weld bead rather than the surrounding area.  The idea is to stretch the weld as it cools to counteract the contraction as it cools.  Use ni-rod which is the correct electrode.
Reply:Dyes are an inexpensive NDT method.
Reply:pre-heat, nickel rod, peen the weld, repeat.Millermatic 251Century 180 migSpectrum 625 Syncrowave 250DX
Reply:Originally Posted by lotechmanPeen the weld bead rather than the surrounding area.  The idea is to stretch the weld as it cools to counteract the contraction as it cools.  Use ni-rod which is the correct electrode.
Reply:Heating after welding is called post heating.  By postheating the contraction rate is reduced and as a result the stresses that cause cracking.  Post heat is applied so that the whole casting is at an even heat rather than just the weld bead.  If a casting is very large and complicated, heating it can be complicated so the alternative is welding short beads, peening and letting cool before doing another short bead.  The main point to understand is that cast iron does not bend and stretch as it cools like mild steel.  It is a very brittle material.
Reply:Originally Posted by lotechmanHeating after welding is called post heating.  By postheating the contraction rate is reduced and as a result the stresses that cause cracking.  Post heat is applied so that the whole casting is at an even heat rather than just the weld bead.  If a casting is very large and complicated, heating it can be complicated so the alternative is welding short beads, peening and letting cool before doing another short bead.  The main point to understand is that cast iron does not bend and stretch as it cools like mild steel.  It is a very brittle material.
Reply:When welding cast iron, you were on track preheating, but erred when you let it cool between passes.  Keep it hot  ~500 deg. F before and through all your passes.  Then bundle it up to let it cool slowly.  Ni-rod is the SMAW rod to use on cast.  Your beads will look like crap as the high nickle does not flow well.  Do not try to increase the current to get it to flow, it won't help but may cause cracking.You should be able to buy a can of penetrant, cleaner & developer at your local welding supply store.  Follow the directions on the cans.  Parts need to be cool to run PT.  Do not spray cleaner directly onto the part to remove the penetrant before developing.  Spray it onto a rag and wipe off the penetrant."Some people are born smart, others have to work at it."