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Hi 123stickweld!
Too much dilution is definitely undesirable!!!
This also depends on quite a few factors...
I have some questions:
Does that MEK have any chlorine in it and is the surface of the 4130 clean and free of any scale???
2. Do you first apply a "buttering" (*309L or P5-309LMo) layer on the 4130 before you overlay with 316L???
3. Are you oscillating your beads as opposed to running stringers in order to achieve less dilution???
4. What is the thickness of the 4130 and why are you preheating to such a high temp and what is your interpass temp???
5. Are you performing Post weld heat treatment???
6. If you're using 25% helium (*increases the arc energy in order to increase fluidity and arc stability which may enable a significantly increased travel speed) in your shielding gas, are you moving fast enough??? Because if you're not moving any faster than you would with a Ar+1-2% O2 or Ar+2-3% CO2 shielding gas mix, then your insufficient travel speed may be the cause of excessive dilution...
7. You say your travel speed is 12-14 inches? per minute???
Is'nt that a bit slow for overlay with 25% helium even if you're oscillating (Weaving) the bead 1" wide???
Anywho, that's enough questions for today but, it seems to me that the procedure needs to be tweaked a bit in order to achieve successfull overlay welding with dissimilar metals such as 316L on to 4130... My Suggestion is to talk to Chuck, otherwise known as "Cmeadows" in this forum because, he's really one of the best resident Stainless steel experts here...
We look foward to your response.
These *facts are referenced from: Avesta Welding's
"The Avesta Welding Manual" - Practice and products for stainless steel welding. ISBN 91-631-5713-6
Respectfully,
SSBN727
Run Silent... Run Deep!!!