Colors of temperatures

[iamdunn4]

Can some one give me the temperatures for the colors that the metal turns during heat treating ?

[GobblerForge]

Will this work?
Gobbler

[pkrankow]

or this?
Temper Colors and Steel Hardness : anvilfire.com
Phil

[D Lisch]

IF you are tempering I would worry more about the spcs for that steel. for ex if you put a bar of 1084 in the oven for 3 hours at 390 after hardening it will turn gold and it will be temper to about 58 rockwell but if you just take your torch and run it up to a gold color you will find that if you test them both the torch bar is still way to hard. good temper takes time.

[Frank Turley]

One must be circumspect when using pigment charts. Pigment charts do do not show incandescence; ie., the emission of light. Charts also indicate that the color is somehow fixed, yet an incandescent color is always changing depending on cooling or heating. Vincent Van Gogh was going off his rocker in his later life. His paintings would indicate sunlight, and he wanted the sunlight in the painting to be incandescent. Ain't gonna' happen. I'm not recommending the discarding of the color charts; they can be a rough guide.

As to tempering colors which result from a thin oxide on bare ferrous metal, there is some question as to how accurate they are, although they have been used for well over two centuries as a guide. I have used them with success on high carbon, plain carbon steel for many shop tools I have made. There is an advantage to "chasing color;" that is, running the heat rainbow toward the business end of an edge tool. The colors run in rough "bands," so that if you tempered a cold clisel to a blue, there will be a pale blue and gray-green color behind the blue. This is what fossils like me term a "cushion." It provides a "shock absorber" for the tool, so to speak. There are many ways to reach the proper temper color for a tool's end use: a hot block heat conductor; oxy torch; reserve heat method, etc.

I trust the chart in the British book, "Metals for Engineering Craftsmen," 1964, which offers temperatures for both tempering and incandescent heats.

http://www.turleyforge.com Granddaddy of Blacksmith Schools

[Rich Hale]

Ambient and totally consistant lighting is a big problem with color charts. What looks like a real bright red or may even towards yellows in a dim room or at night outside maylook like a dull red in sunshine or may appear even darker than that. A tip to learning to forge is to provide a consistant shop lighting so yui can learn what colors do in the steel you are forging. And also remember that what I call bright red you may call another shade of red.

[thecelticforge]

Yeah, what Frank and Rich said. I know almost all of you will know I am a nutter when I say this but: I swear I can feel how hot the billet is through my tongs. Like I said, nutters. It's my delusion and I worked years on it and I am gonna keep it!

[forgemaster]

When I first started work for myself, one of the first jobs I got was sharpening jack hammer moils, done heaps of them when I was working for a boss. Now about half of mine were coming out a brittle as glass, snapping like carrots, what I figured out was, the quench tub was on the western side of the shop, in front of a window, in the morning the sun was not coming through this window and I was judging the incandesant heat correctly to quench. In the arvo the sun was coming straight through that window so I was quenching my moils about 150 degC hotter than the morning, even though to my eye the colours were the same. I put a blind over the window, and my breakages stopped.
Moral, you have to have constistancy of light to use sight as a means of judging heat. Now if we are forging temperature critical metals we will test the temp by use of an optical pyrometer, or we will set up the furnace with a thermocouple and a digital readout.

Cheers
Phil