Welding temps

Freds Edge

Freds Edge

Well-Known Member
I know this may be a broad question but I was wondering if there is a general reference guide for forge welding temps. I build a pyrometer from Ed's design that works very well but I know from reading that various metals require different temps for successful forge welding and was looking for some kind of guide to start me on my way.
 
Well first attempt was a failure , popped my two 1080 bars apart and no weld in the center at all . After dinner I will clean them up and go for a higher temp , 2200 on the pyrometer or higher.
 
In general you can get an idea of welding temps based on the carbon content of a given steel. Those with higher carbon content (such as 1095 or 1080) weld nicely in the 2250-2350F range. As carbon content decreases in a steel, the welding temp increases. The other key is duration of exposure to the heat, or another term you could use is "soak time". Of course the larger the cross section of the material you're trying weld, the more "soak time" it need to ensure the heat equalizes all the way through the stack/billet.

Personally, If I'm working on my standard starting billet (6" long X 1 1/2" wide X 40-50 layers), I don't even put the billet into the forge until the pyrometer hits 2350F. The "soak time" is all relative.... meaning that knowing when the billet is ready to bring out and work on, is more a matter of time and experience then anything. This might sound strange, but I've been doing this for so long now that I just "get that feeling" when a billet is ready to weld.

About the only visual Que that I can offer as an example is to look at the steel, and if there are any "shadows" or darker shades (usually near the center of the ends, or a slightly darker line down the centerline of the billet) then around the exterior, leave it for a few more minutes. The other key is to NOT reef on it with the hammer when starting the weld. Light to medium blows is all you need. The first few hits will feel "mushy" under the hammer, but when the weld "takes", things will stiffen up significantly....then you can "reef" on it. Hitting too hard at the start of a weld will cause the surfaces to "slide" over each other and will usually result in a void.....that you likely won't know about or see until you grind into the billet, and the void jumps out of nowhere. :)
 
Thanks Ed , I did a weld after dinner and allowed the forge to reach 2200 F , it seems to stall at that temp but I think if I open the needle valves a bit more and a bit more regulator pressure I will be able to reach 2300 F or so . I did do a weld at that temp and seemed to be successful ,I tried to drive a coal chisel into any of the seams with no results . The success will increase with practice and as you say one will develop a feel for the steels reaction under hammer.
My goal is a Tomahawk so I want to be sure my welds are strong and void free. Thanks again for the help , your the best.
 
A few years back, I was wondering what sort of temperatures were realistic for welding bladesmithing-type steels and nobody seemed to be able to give a firm answer. I took a type S thermocouple and pyrometer along to a hammerin where a number of good smiths made quite a lot of Damascus over a couple of days, using a vertical gas forge that one of them had brought along. He fired it up and adjusted it how he wanted it, then everyone used it. Nobody said it was too hot and nobody said it was too cold. All the comments that I heard were to the effect that it was good and hot. Late on the Sunday, I stuck the thermocouple in and took some measurements. Temperature took a bit of a dive when a workpiece was first put in, but quickly recovered to around 1285 degC/ 2345 degF. Typical temperature when the workpiece was removed was between 1295 and 1310 deg C (2363 to 2390 degF). With no workpiece in, the temperature reached 1330 degC (2426 degF).

As is the way of such things, curiosity got the better of us and it got turned up to see what it would do (pressure set to maximum and choke adjusted to give peak temperature). We got 1440 degC (2624 degF) where the workpiece normally sits, with a spot reading of 1470 degC (2678 degF) an inch or so below. The experiment melted the lining.

Whilst it is clearly possible to weld at lower temperatures, the consensus seemed to be that 1300 degC (2340 degF) was about right and that if welds were not good at that temperature it was not because of the temperature.

Identified steels being welded included 15N20, 20C and EN42, along with a pretty varied assortment of other stuff.
 
I use hydrocarbon solvent and weld most all high carbon steels at 2200. Try it, its a very clean way to weld.
 
JawJacker said:
Mr Fred how are you applying the solvent? spraying it.
Click to expand...

I use parts cleaner from Tractor Supply and just soak the ready billet in it for a couple of minutes before setting it in the forge. One thing with HS is once it is in place in the forge let it sit. What is taking place is the HS, as its consumed leaves a 1/16 inch thick jacket, completely covering the billet. This is how the oxygen is kept from the surface of the steel. I welded with borax for years and it worked fine but I like the HS better. the welds are cleaner along with the process; no burned out forge lining. You have to make sure the virgin billet is welded securely along the sides so there is no movement from expansion during heat up.

It works best when using a press.

Regards, Fred
 
I tried the same thing after using borax a few times. I wasn't happy with the borax and read up on blacksmith using kerosene for welding. I wired up a small billet and put it in jar with kerosene while my forge heated up. It worked great and burns off almost immediately after placing in the forge. No need to keep fluxing either, heat, weld, repeat. As Fred said, ensure its complete on the sides and you should be fine.
 
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