Trouble wih Metal core

Date 07-13-2012 12:41

Hey guys,
We've recently switched to a metal cored wire from a solid L-59 wire. What we're welding is similar to a B-U9 joint on I beam. With dye pen testing after back gouge. What I'm running in to is cracks and porosity. I'm making sure they are cleaning between passes, I checked their amps and even gas flow pressure, but I can't seem to figure out whats happening. Any advise would be greatly appreciated.
Thank you,
Scott

By CLH1978 (**)

Date 07-13-2012 16:53

Hi sriley77. Please provide more info. Type of base material, shielding gas, wire chemistry,etc. Are you following a WPS?

By sriley77 (*)

Date 07-13-2012 18:59

Material is A 572 GR 50 Beam W18 x 46. Wire is E70C-6M H4 .045, and Arg. + 10% Co2. Its all pre-qualified joint configurations.

By P3T3R ST33L (*)

Date 07-13-2012 21:30

Did you check the gas flow at the cup? I have had many a whip develop a leak. I would also watch them weld and make sure they are not running to much stick out. Make sure the diffuser is clean and not plugged with that cup dip garbage that everyone insists on buying. Outside of that someone smarter than me may be able to help.

By Sourdough (****)

Date 07-14-2012 05:19

Sometimes even a cracked shop door can blow your gas enough to start the porosity. After it starts, you might as well cut it out and start over. It sounds to me like it's a gas issue. Bad regulator?

By jwright650 (*****)

Date 07-14-2012 11:53

Our experience with those MC wires wasn't a good one either...we had random porosity, never consistant...just appeared at the most inconvenient times(somewhere a grinder won't fit). We even had the wire mfg's rep spend tons of time with us and he never could figure out what was going on. We could have a problem, stop and snip the wire and spool out a few feet, then it would weld fine for quite awhile and then porosity would just show up again without warning. We switched gasses, replaced equipment, even operators and it didn't make any difference. There are discussions about this on this forum, if you search through the archives, i'm sure you can find lots of reading on the subject.

By 803056

Date 07-13-2012 23:21

Check the tip to work distance.

The importance of the distance from the contact tip to the arc is often overlooked. Different manufacturers use different terms, i.e., electrical stick out, contact tip to work distance, etc., but the concern is the same. It is a distance that must be controlled, but rarely do WPSs list the dimension suggested by each manufacturer. It is dependent on the specific manufacturer and the classification of the electrode, i.e., what works for no manufacturer's electrode is not appropriate for the same classification manufactured by another manufacturer.

Al