porosity - welding mild steel, 7018 rod

[Sodo]

Thought about the woodstove, thats more feasible than running a generator.

Seems to me if there was a problem with moisture it would be the flux chunking off. I have a hard time believing moisture can get into the puddle.

 

[CNC Dan]

Thought about the woodstove, thats more feasible than running a generator.

Seems to me if there was a problem with moisture it would be the flux chunking off. I have a hard time believing moisture can get into the puddle.

Moisture no. It will be turned into super-heated steam before it gets that far. But the steam will break down into hydrogen and oxygen at arc temperatures. And iron, when hot, can absorb hydrogen. And when iron cools, it can't hold as much hydrogen. There is a good video on youtube that shows hydrogen coming out of a fresh weld. I'll see if I can find it.

Found it:
http://www.youtube.com/watch?v=bv9ApdzalHM&feature=youtube_gdata_player

Also, the water in the flux coating isn't just soaked in. It is bound into the chemicals.
See "water of crystallization"
Water of crystallization - Wikipedia, the free encyclopedia

That's why you need to heat them way above the boiling point to drive the water out.

 

[Gary Fowler]

Also rods that are left exposed to as much humidity as they can adsorb will eventually rust the wire that the flux is coating. Even if they are then dried out to the max, the rust on the wire will cause just as much porosity. If you are going to buy iron powder electrodes, ie 7018, 8018 etc, you have to keep them dry. Rods sold at hardware stores are stored in air tight plastic bags and should not be purchased if the bag is torn or has pinholes in it.
I buy mine in hermetically sealed steel cans and after opening, they go into a hot box at 350F full time. If I didn't have a rod storage oven, I would put them in a vacuum sealed bag like you store food for freezing in. This would keep them dry forever. You could remove a few and then reseal the bag. Even a plain old Ziploc freezer bag might work but eventually after opening and closing it several times, the rods would need to go into an oven @ 375F or higher for a couple of hours to dry them out again prior to storing. A good check for moisture is to take a whole rod and stick it so it heats up and watch for a puff of steam. If you get that then they are wet and need drying. If it heats up red hot and doesn't show off any escaping steam, then it is dry enough to use.

Many of the welds in the photos show evidence of what is called worm hole porosity. Even though it isn't open to the surface except at the end of the weld (as evidenced by the small hole at the base of the fillet), grinding into the weld metal will usually reveal a lot of sub-surface porosity when wet rods are used or even if electrode is long arced or exposed to lots of wind. Not all porosity is open to the surface.

 

[Sodo]

Interesting stuff!

I'm not going to have an oven. But it's quite feasible to lay them ontop of the woodstove for a few hours, it's plenty hot.

Haven't seen this before. Also I'll try to avoid "using up" the last quarter inch of rod. :laughing: (as I did in the original pics). Are you saying it's less of a problem with 6010 and 6011? I was kinda liking this 7018 (the hero rod!)

 

[Shield Arc]

Are you saying it's less of a problem with 6010 and 6011?

Sometimes 6010, and 6011 get too dry, and you have to recondition them. Then they run like new.

 

[Gary Fowler]

Sometimes 6010, and 6011 get too dry, and you have to recondition them. Then they run like new.

I have had to do that in desert or semi-arid places but never here in Ark. Humidity is always above 40% here so I just keep 60xx rods in a plastic box laying on top of my welding machine which is next to the roll up door at my shop. They run fine that way.

A quick dip in water and then allowing them to dry will usually fix a 60xx rod that is "finger nailing" (for the beginner welder : that is when the flux is not burning off evenly and leaving a long "nail" on one side). DONT do this with iron powder electrodes like 7018.

 

[Shield Arc]

You wouldn't think here in the Northwest 6010 would dry out, as much as it rains! Maybe they set on the bench too long.

 

[MinnesotaDaveChalmers]

Interesting stuff!

I'm not going to have an oven. But it's quite feasible to lay them ontop of the woodstove for a few hours, it's plenty hot.

Haven't seen this before. Also I'll try to avoid "using up" the last quarter inch of rod. :laughing: (as I did in the original pics). Are you saying it's less of a problem with 6010 and 6011? I was kinda liking this 7018 (the hero rod!)

If you want a "hero rod" try 7014 - almost run themselves and leave a smooooth finish

 

[CNC Dan]

If you want a "hero rod" try 7014 - almost run themselves and leave a smooooth finish

Look at 1:55
They DO run themselvs!


http://www.youtube.com/watch?v=c7509VJZZ80&feature=youtube_gdata_player

 

[notme]

Interesting stuff!

I'm not going to have an oven. But it's quite feasible to lay them ontop of the woodstove for a few hours, it's plenty hot.

Haven't seen this before. Also I'll try to avoid "using up" the last quarter inch of rod. :laughing: (as I did in the original pics). Are you saying it's less of a problem with 6010 and 6011? I was kinda liking this 7018 (the hero rod!)

quite often in the winter if iknow im gonna be welding i'll throw a dozen rods on top of thw woodstove, you can actually see them lighten in color a little as the moisture drys out of the them and it solved the porosity issue. but come summer time the stove aint on and I'm too cheap to pay for a power sucking oven to run 24/7!!