Not the first time I've said it...andygmac wrote:...I think I could have done better, but I'm always self critical...
Cheers Andy
We like to call ourselves craftsmen, so we are always our own worst critics.
Steve S
Not the first time I've said it...andygmac wrote:...I think I could have done better, but I'm always self critical...
Cheers Andy
At the school I go to, 12mm (1/2 inch for us barbarians), is about the beginning of the range where we start to pre-heat. Not sure if your spec allows for it or not. Is there a interpass temp you have to maintain?andygmac wrote:Nope, no pre heat, just ambient temperature which was around 28°c in the shop
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.andygmac wrote: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
Cheers for thatAxis wrote: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
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.andygmac wrote:Cheers for thatAxis wrote: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
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"