[Axis]

Hardness in the HAZ is usually caused by too quick of a cooling cycle, and is extremely common in MIG/GMAW and on thicker material. As I mentioned before, a pre/post heat, and slow as possible post-weld cool down will reduce the possibility of that happening.

Read up on cold cracking and hydrogen diffusion.

Hobart has an easy to understand article on it.
http://www.hobartbrothers.com/index.php ... turnid=523

[Otto Nobedder]

I got the test results back today, passed the procedure test for multi run 20mm fillet, failed on procedure tests for, 12mm single fillet, and 12mm multi run v butt, both failed on "hardness in heat affected area" . so my weld shape, leg length, fusion, penetration, macro, and x-ray were fine, just failed on something that I can't check myself to improve on lol

So, I'm happy in a way that I passed one procedure test, (being the first tests I have ever attempted, and knowing procedure tests are scrutinised more than welder tests)
But gutted that I failed, not on my weld as such, but on the surrounding base metal , grrrrrrr.
Andy

That's the story of a welder's life. If you meet a man who's never busted a test, you've met a liar.

Steve S

[andygmac]

Hardness in the HAZ is usually caused by too quick of a cooling cycle, and is extremely common in MIG/GMAW and on thicker material. As I mentioned before, a pre/post heat, and slow as possible post-weld cool down will reduce the possibility of that happening.

Read up on cold cracking and hydrogen diffusion.

Hobart has an easy to understand article on it.
http://www.hobartbrothers.com/index.php ... turnid=523

Cheers for that

Pre and post heat would be an option but we are trying to avoid this because if any heat is used in the procedure test, then it would have to be used in every weld thereafter which in our production would cost time and money lol

The strange thing with my fails were that they were both on the 12mm plate, one v butt multi pass (7passes), and one single pass fillet. The passed test was 20mm plate multi pass fillet. It was hot on the test day with the workshop having an ambient temp of around 30°c. All test pieces were allowed to cool on the bench, no quick cooling.
There were no cracks found in any of the welds, they were x rayed, mpi, cut, bent, etched, impact tested, and inspected under a microscope, and the fail was hardness in the haz.

A good workman always blames something else, so I'm blaming the 12mm plate he he he

You are right Steve my motto is " he who has never made a mistake, has never made anything"

[Superiorwelding]

Hardness in the HAZ is usually caused by too quick of a cooling cycle, and is extremely common in MIG/GMAW and on thicker material. As I mentioned before, a pre/post heat, and slow as possible post-weld cool down will reduce the possibility of that happening.

Read up on cold cracking and hydrogen diffusion.

Hobart has an easy to understand article on it.
http://www.hobartbrothers.com/index.php ... turnid=523

Cheers for that

Pre and post heat would be an option but we are trying to avoid this because if any heat is used in the procedure test, then it would have to be used in every weld thereafter which in our production would cost time and money lol

The strange thing with my fails were that they were both on the 12mm plate, one v butt multi pass (7passes), and one single pass fillet. The passed test was 20mm plate multi pass fillet. It was hot on the test day with the workshop having an ambient temp of around 30°c. All test pieces were allowed to cool on the bench, no quick cooling.
There were no cracks found in any of the welds, they were x rayed, mpi, cut, bent, etched, impact tested, and inspected under a microscope, and the fail was hardness in the haz.

A good workman always blames something else, so I'm blaming the 12mm plate he he he

You are right Steve my motto is " he who has never made a mistake, has never made anything"

First thought, you can put the test piece in a bucket is sand or wrap in fiberglass, this will allow for a slow cool and you might be able to get away with this. However, it is best to figure out why this is happpening and how to fix it. I would hate for you to have problems in the future.
Ok now define "hardness in the HAZ". What was acceptable and where did you fall? I will try to get a friend to help out with this one, hopefully.

Steve,
Took the words right out of my mouth!!
-Jonathan

[andygmac]

Cheers Jonathan, I'm waiting for the paperwork to come back to me, the test lab is real busy at the moment so they just emailed my results to me, with the paperwork to follow, hopefully this will give me more of an idea what went wrong, I'm still blaming the 12mm plate lol
Cheers Andy

[Superiorwelding]

Andy,
Anxious for a update! What did you find out?
-Jonathan

[andygmac]

Hi Jonathan, would you believe I only got the paperwork through today
My butt weld passed on every test bar the hardness test, it had 38 different "dots" where it was tested, from parent metal through haz, through weld, through haz on other side, and into parent metal . out of the 38 dots, 2 were over hard, gutted.
Much the same results for the single pass, and pipe to plate test.
The strange thing was, there was only hardness in the 12mm plate in all tests, there was no hardness in the pipe in the pipe to plate test , only the plate?
Another thing I noticed was the hardness of the actual unaffected parent metal, the 12mm plate was 11% harder than the 20mm plate, and 17% harder than the pipe, but they were all supposed to be the same grade, S355j2.
So the 12mm plate was harder to start with, if it had been 10% softer I may have passed?
Just got to get a new batch of steel, and get the inspector round again and give it a go again, at least I know I can weld to a standard, so bring it on lol

Cheers
Andy