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Tempering and Heating Colors

The color metal turns when heated is the blacksmiths primary means of knowing what temperature it is at. The first set of colors is created by the thickness of the layer of oxide that forms on the surface of the iron as it is heated, these are referred to as annealing colors. The second set is produced as the iron begins to glow with heat, these are referred to as heating colors.

Temperature Color of Heated Carbon Steel
°F °C
2192 1200  
2012 1100  
1922 1050  
1796 980  
1706 930  
1598 870  
1490 810  
1400 760  
1292 700  
1202 650  
1212 600  
Temperature Color of Annealed Carbon Steel Common Uses
°F °C
600 316   Scrapers, spokeshaves
560 293   Screwdrivers, springs, gears
540 282   Cold chisels, center punches
520 271   Taps <= 1/4 inch
500 260   Axes, wood chisels, drifts, taps >= 1/4 inch, nut taps, thread dies
480 249   Twist drills, large taps, knurls
460 238   Dies, punches, bits, reamers
450 232   Twist drills for hard use
440 227   Lathe tools, scrapers, milling, cutters, reamers
430 221   reamers
420 216   Knives, hammers
Data Loom Design, Inc. Copyright© 2010 Updated: 4/10/2016