Dirt, I don't know dick about welding but thanks.
Seriously though, this isn't the right section and googling "Chromoly welding filler" or "4130 steel welding filler" would've been a LOT faster and more hassle free than asking us.
Read the rules. No pics = no thread. Get pics and make a new thread. if you make a new thread without pics you're banned for a week.
you should know this kind of stuff dude.