Gas Forge temperatures

[Domnu]

Hi, I am kinda new to gas forges and was wondering what temperatures a good gas forge for general forging and welding should achieve. I just built mike porter style gas burners for my forge and tested them. I hear a lot of people saying they get a "white hot" heat in a gas forge. I don`t really seem to get that. It is more like a yellow color. I only ever get real white heats in my coal forge .  I use insulating firebrick in the forge and the burners seem to work fine. The temperatures i get are around 1400 °C at 15psi with a 0.023" orifice as far as i can tell (measured with k-probe and IR-thermometer). Is that hot enough for good forge welding ( I haven`t really had time to try yet)? I do not seem to get the sparkling heats i sometimes get on the coal forge, but i figures that might just be due to a more reducing atmosphere. What temperatures do you guys get in your gas forges?

[timgunn1962]

The highest I have measured in a Propane forge was 1556 degC (2833 degF) and still rising. I didn't want to risk the $400+ typeS thermocouple, so didn't wait to see what it would top out at. I measured a forge at a hammerin a few years ago. It was being used for pattern-welding blade steels and was right around 1300 degC (2372 degF). As I understand things, it had been adjusted to give a temperature suitable for "anyone" to weld in and I regard 1300 degC as a good target temperature for a (bladesmiths) welding forge. The more experienced pattern welders tend to use a lower temperature (probably around 1200 degC) because it gives crisper contrast between the different-coloured layers.

One caveat is that High-Carbon blade steels tend to need lower temperatures than lower-Carbon steels or Wrought Iron. However, if you are getting 1400 degC and have Dragons Breath (The DB is a sign of a reducing atmosphere: a secondary burn that takes place when hot, partially-burned gases reach fresh air containing enough Oxygen to complete the burn), you should be ok for welding pretty much anything.

[pnut]

3 hours ago, Domnu said:

I just built mike porter style gas burners for my forge and tested them. I hear a lot of people saying they get a "white hot" heat in a gas forge.

He will eventually be around and you can ask him. 

Pnut

[Glenn]

If the forge gets hot enough so you can move the metal, who cares what the temperature is.  It is just a number.  

If you want a specific temperature number, that takes things into industrial forging, which means specific tools and tooling for the production of thousands of pieces of work.  You then need a LOT (tons) of a specific metal or metal alloy that uses THAT temperature number in order to feed the beast.  Control of all phases of the operation comes into play for repeatability.  If you have to ask how much that costs, then you can not afford it.

 

[Frosty]

Welcome aboard Domnu, glad to have you. Most of us judge temperature by color and effect. With good prep low yellow is easy welding heat for anything but wrought iron. I do most of my forging at low to mid yellow heat. 

Backsmithing at our level really isn't a science, it's mostly eyeball and feel. New folk breaking into the craft often want the best equipment in the false belief there are some specific or magic: numbers, tools, tricks, etc. that make things work. Twice I've had guys who sought me out stomp out because I wouldn't tell them THE SECRETS. 

You forge in coal or charcoal, all you need do is get used to a different shape and size fire. Fire is fire propane just heats a much larger area, you only have to adjust. It's not hard and we'll help if you run into a problem.

Frosty The Lucky.

[Mikey98118]

What those people have said about their results are true. And what Glenn said is true, as well; wite heat is irrelevant. Any forge that gets to yellow heat is all you will ever need. Bigger is seldom better, and hotter is also seldom better. Build the hottest burner/forge combination you can--then turn it down to a sane and safe heat!!!

So, how about all those people, with forges that "only" get to yellow heat? They have lost nothing but bragging rights, and a little fuel. I suggest that nobody cares if they spent an extra dollar building something really extraordinary--just how good it looks

[Saint 5150]

I'm building a forge out of an old water heater and was wondering if I could crush up lava rock and use as insulation

[Frosty]

Welcome aboard Saint, glad to have you. If you'll put your general location in the header you'll have a chance of hooking up with members within visiting distance.

What on earth are you planning on doing that's going to need a forge that big? If you need a commercial sized forge furnace you'll be WAY ahead to build it from scratch with proper materials. You do NOT see commercial furnaces made from salvaged materials, not in 1st. world countries that is.

The short answer is probably not, lava rock melts at or below 2,000f and a typical propane forge tuned properly hits 2,600f+ easily. 

Frosty The Lucky.

 

[ThomasPowers]

Usually when folks say they want to build a huge forge they go on to tell us that they want to forge swords. Unfortunately they don't know enough about forging swords to know that you DON'T want to heat up more metal than you can work before it cools as you get scale losses, grain growth and decarburization, things you don't want to encourage!  A forge with 6-8" hot spot will forge a sword and cosh a heck of a lot less in gas to do it!

So what do you plan to do with your forge?

(Also note: lava rock is generally not very insulative, using it in the forge means you should budget several times as much money for propane as you saved not using a good insulator---the old "I spent $200 to save $50!")