anvilfire.com Steel Temper Colors

Plain Carbon Steel Only - Hardness Rockwell C

English Color Text	Fahrenheit	Color	Celsius	SAE 1040	SAE 1050	SAE 1070	SAE 1095
Clear - As fully hardened	100°		38°	54	59	64	67
Pale yellow ²	420°		216°	51	55	59	63
Very pale yellow ¹	430°		221°
Light yellow^{1, 2}, Straw³	440°		227°
Pale straw-yellow¹, Straw³	450°		232°	50	54
Straw-yellow^{1, 2}	460°		238°				62
Deep straw-yellow^{1, 3}	470°		243°
Dark yellow¹, Light orange³	480°		249°			58
Yellow-brown¹, Orange³	490°		254°	49	53		61
Brown-yellow^{1, 3}, Bronze²	500°		260°
Spotted red-brown¹, Dark Brown²	510°		266°
Brown with purple spots^{1, 2}	520°		271°		52	57
Light purple^{1, 2}, Purple³	530°		277°	48			60
Full purple¹, Purple²	540°		282°
Dark purple¹	550°		288°
Full blue^{1, 3}	560°		293°	47	51	56	59
Dark blue¹, Blue²	570°		299°
Dark blue²	590°		310°				58
Pale blue³	590°		310°	46	50	55
Light blue²	610°		321°
Greenish blue², Grey³	630°		332°	45		54	57
Light blue¹	640°		338°
Steel grey²	650°		343°	44	47	53	56
Steel grey	700°		371°	42	46	51	54
	750°		400°	40	44	50	52
	800°		427°	38	42	47	49
	900°		482°	35	37	43	44
Lowest visible red	1000°		538°	30	32	36	39
English Colour Text	Fahrenheit	Colour	Celsius	SAE 1040	SAE 1050	SAE 1070	SAE 1095
Converted temps. rounded to nearest degree. Hardness +/- 1Rc @ +/-5°F of published data.

Colors represented here are approximations and at best require a millions of color computer monitor adjusted correctly to view them. The colors as represented do not show the metallic luminosity of the bright steel surface on which the colors are transparently overlaid. For true colors a sample should be made of polished steel. Printed the colors above may or may not print as they are HTML "background".

1 Machinery's Handbook, 18th Edition, 1970, Industrial Press (Color text the same from 5th to 20th Editions with exception of the addition of Light blue at 640°F)

2 Edge of the Anvil, Jack Andrews, 1977, Skipjack Press.

3 Metals for Engineering Craftsman, C.O.S.I.R.A., London England. Temperatures given at tens and fives in Celsius. Example: Purple = 275°C / 545°F

4 ASM Heat Treaters Guide, Hardness data compiled from graphs by author September 2006 using this and other references in agreement.

Note that maximum hardness and tempered hardeness vary as much as 2 points Rockwell depending on the chemistry of the steel within its specification range. An increase in carbon or manganeses makes deeper hardening steel and less makes it slightly softer and not as deep hardening.

Revised June 26, 2003, September 2006 added hardness data. 28,697 / 8,981,534

2002, 2006 Jock Dempsey, www.anvilfire.com