Cast iron welding

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Hey guys    Been a long time since I posted . I have to weld a broken small sheetmetal shear ,blade support . It has broken just above where cylinder attaches . It appears to be gray cast iron . I have welded cast with ni55 before , what I,m concerned about is if  this part can be welded well enough to be close to its original strenght ??  What special precautions should I take ? what electrode  ?                                                                           Thanks Larry
Reply:Welding cast iron is a hit or miss venture. If strength is  of utmost importance replace the broken part with a new manufactured piece.
Reply:Hello         Yes from all the reading I,ve done on it your probably right . I,ve welded some cast with rod and also braze before but never apart thats under a lot of stress. I,m just going to give it a go                                     LarryLast edited by laurance D; 08-01-2011 at 08:10 PM.Reason: spelling
Reply:ni 44 is better for gray cast and its stonger than the 55no need for pre- and post- weld heat on smaller jobs
Reply:Hello Thahnks for the replys       An welding buddy of mine swears by brazing cast iron .                                        Larry
Reply:yeah, it's hit or miss.I welded a buddies log support for his fireplace.I used nothing but flux core and I managed to get a nice weld on there.But it took me many failed attempts.Lincoln 125HD, yep I'm a big spender.
Reply:hey all welders                        I finished welding cast part . I ended up using 11018 rod . then ni55 over after crack appeared in one side of parent material . used dye penetrant to track any cracking .  ,                                                       Laurance
Reply:Hello     Thougt Id, do an update on the cast iron weld , BROKE  AGHHH! It broke above the weld .  I will try and fishplate on 3 sides with mild steel and weld with nic 55 . This is a 12 ga, shear part , t\he yoke part that one of the two hyd. cyls attach to . Whats your opinions out there ??                     Thanks    Laurance
Reply:Are you sure it's cast iron? A part with that kind of stress might be cast steel. Your mistake was using the 11018 rod if it was cast. Use ni44 on it if it's cast, and peen it a bunch right after you weld it. Don't weld more than an inch at a time and then peen. Don't "V' groove it, "U" groove it. Just remember that cast can't expand or contract like steel can so peen it to releuve the stress that you put in it.
Reply:Bob   Thanks for the input . I will reweld with nickle rod also like to fishplate for extra insurance . Take your advice U grove and peen welds . addafix  brand  was recomended to me .                               Laurance