Lowest Possible Temp.
Posted 13 March 2012 - 04:32 PM
What is the lowest temperature that you can set a weld with?
I am questioning the fact that I have to run my forge at 2300 degrees to get a good weld.
I understand that mild steel if used in your billet will require a higher temp, but if using all high carbon material could you get away with like 1900 degrees?
Thanks in advance.
Dave from Diller
Posted 14 March 2012 - 07:31 AM
It's sometimes a bit difficult to grasp, but it's not necessarily about the temp the forge is running at, but more so about the temp of the steel. I won't even put a damascus billet in the forge until the forge is running at a steady 2350F or higher. It's all about paying attention to your steel, and duration you leave it in the forge. There's also the matter of how each individual "looks" at their methodology. I choose to use the temp range I mentioned to ensure a good foundation (in other words I want to ensure that first weld "takes). I can use thermal cycling, and other methodologies towards the end of the forging process to ensure I "repair" any grain enlargement that the higher welding temps may have caused. What I can't do is repair a weak or marginal weld....so for me it's "first things first".
If my intuition is right, we're both thinking the same thing.....your just trying to avoid the issues to begin with, versus me dealing with them later in the process. My mindset is to always take it one step at a time, doing each of the steps (in this case, welding) in such a manner that it makes that particular "step" the best I can make it, then "fix" any "side effects" as necessary......not sure if that makes sense, but better wording escapes me.
Posted 14 March 2012 - 04:21 PM
I'll expand a little bit on my concern. The forge I currently use is not all that controllable as far as temperature. It pretty much runs wide open. I'm sure it is near 2350 at all times. I will be able to expand on this since I've purchased a digital thermometer (should be in tomorrow).
Dave from Diller
Posted 17 March 2012 - 09:20 AM
The answer is for you to run your billets in your forge at 1900 and see how it works. If your welds are good then you are on. If not, adapt and move on.
There is more to it than temps; as Ed stated. Welding and then bending tells you a lot about your process.
Posted 20 March 2012 - 04:55 PM
Thanks for the reply. When you refer to more than to it than temps; are you referring to air and gas mixtures. As I understand it a lean fire is better than an air rich environment.
Okay, I've finally found the error in my question. You have to take into account the weld that you are doing. Closed or sealed weld vs. open weld or tacked welded layers. With an open weld we would have to take into account all factors as with a closed weld (Mosiac) you'd eliminate several factors.
Dave from Diller
Posted 21 March 2012 - 08:15 PM
I would have to agree with Ed use the temp you need to get the best weld you can, then sort out grain size after. Having said that, one thing I have changed in recently is my soak times. They have gotten much shorter through the use of a Pyrometer. I see through your post that you have ordered one which would have been my first suggestion. I welded for 15 years without one and that was 15 years too long. I mostly use 15n20 and 1075/1080 as my Damascus mix so the following relates to that. I run the forge and weld at 2315. Like Ed my forge is well at temp before i ever put a billet in. The pyrometer will allow you to watch what happens when you put a mass of metal in the forge. the temp will drop until it hits an equilibrium point, then slowly rise. After a certain point the billet appears to climb with the forge when it is still well under 2315. When the forge hits 2315 the billet hits 2315 at the same time, pull it and weld. I don't even have to look in the forge anymore. And I only soak at temp for 10 seconds or so. So far it works every time. At first I was concerned that a bigger billet would require a long soak but billets up to 3"x1.5"x6" take the same time as the final weld on a mosaic blade.
I would suggest that you get some control on your forge, flat out all the time is not helpful for you. I also prefer some thermal mass in a forge. Plenty of people seem to do well with just Kaowool but I prefer the shorter rebound time if you have some cast-able refractory or hard fire bricks in there. While this may sound off topic, it seems to relate to welding times and temps. It has been my experience that if a forge has some thermal mass in it the reheat time is shorter when you put the billet in. The less time it is in the forge, the less scale, so the less work the flux has to do. Cheers
Posted 22 March 2012 - 09:54 AM
As I understand it a lean fire is better than an air rich environment.
Dave from Diller
It sounds like you don't have the option of adjusting both air & gas for your forge. I don't adjust the air and try keep approx. 6" of yellow flame coming out of the door of the forge by adjusting the gas flow. This will give you all of the gas rich environment that you need.
I think that you will like the pyrometer. I have used a thermocouple & pyrometer for some time now and find it a big help. (If you start to eventually get varied readings for temperature then it is probably the thermocouple as they have a limited life span.) I position mine approx. 1" inside of the kaowool and about two inches below the top of the forge which seems to work well for me.