Crater cracks in SS cladding

By - Date 10-17-2000 12:56

Try not stopping without a short pause to fill the crater. When you stop abruply the crater pool is shallow and could induce crater cracks and thats very common. However not visually appealing, crater cracks are usually acceptable provided the crack does not probigate outside the crater. Also could try a run off tab????

By Tim Buyle (**)

Date 10-20-2000 06:03

Thanks for the reply. But, how can i fill a crater with SAW ? Don't have such function on the machine.

By dong won oh (*)

Date 10-19-2000 16:51

I would like to recommend two points;
1) Equipment point of view
Genenally, FCAW or GMAW have a function of crater filling to avoid crater cracking by using low current and filling the crater.
SAW does not have this kind of function and seems to sensitive to crater cracking.
If your FCAW welding machines does not have this function, it is also sensitive to crater cracking. Try one with crater filling function.
2) Metallurgical point of view(Ferrite content)
If you use saw with 309L, I expect very little delta ferrite due to high dilution(refer to Schaffler diagram).
Subsequent welding with 308L could show very small amount of delta ferrite due to 1st bead.
You can choose welding consumables which show higher ferrite content as possible.
Any method which can reduce dilution will help.
(Low current, small diameter, weaving, push angle)
Delta ferrite content also depends on welding condtions. Please check your weldment.
312(L) may be a substitute for 309L.
If you want use higher welding current with SAW for productivity, 312 which has much higher Cr content can help you with much more ferrite.

By Tim Buyle (**)

Date 10-20-2000 06:01

Crater filling with FCAW is no problem for the welding machine. Concerning the ferrite content : our customer wants the ferrite to be limited (max. ferrite number 8, Schaeffler diagram) ; after measuring the ferrite we find max. 3.5 ; But if the ferrite is to low, why does cracking only occur in the end crater ?

By - Date 10-20-2000 14:28

SAW "STOP TRAVEL" FOR A SECOND OR TWO THEN TURN OFF POWER.

By dong won oh (*)

Date 10-25-2000 11:33

Crater is more susceptible to hot cracking than main bead from solidification point of view and stress point of view.
Your specification limit the maximum ferrite number because of corrosion property. If you have 3.5 or lower ferrite number you have more chance to hot cracking.
** please check ferrite content(or number) of 309L weld deposit.