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Steel Temper Colours

Plain Carbon Steel Only - Hardness Rockwell C

English Colour Text	Fahrenheit	Colour	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}, Straw ³	440°		227°
Pale straw-yellow ¹, Straw ³	450°		232°	50	54
Straw-yellow ^{1, 2}	460°		238°				62
Deep straw-yellow ^{1, 3}	470°		243°
Dark yellow ¹, Light orange ³	480°		249°			58
Yellow-brown ¹, Orange ³	490°		254°	49	53		61
Brown-yellow ^{1, 3}, Bronze ²	500°		260°
Spotted red-brown ¹, Dark Brown ²	510°		266°
Brown with purple spots ^{1, 2}	520°		271°		52	57
Light purple ^{1, 2}, Purple ³	530°		277°	48			60
Full purple ¹, Purple ²	540°		282°
Dark purple ¹	550°		288°
Full blue ^{1, 3}	560°		293°	47	51	56	59
Dark blue ¹, Blue ²	570°		299°
Dark blue ²	590°		310°				58
Pale blue ³	590°		310°	50	55
Light blue ²	610°		321°
Greenish blue ², Grey ³	630°		332°	45		54	57
Light blue ¹	640°		338°
Steel grey ²	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.

Colours represented here are approximations and at best require a millions of colour computer monitor adjusted correctly to view them. The colours as represented do not show the metallic luminosity of the bright steel surface on which the colors are transparently overlaid. For true colours a sample should be made of polished steel.

NOTE: The colours above may not print correctly as they are HTML "background".

1 Machinery's Handbook, 18th Edition, 1970, Industrial Press (Colour 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 of manganeses makes deeper hardening steel and less makes it slightly softer and not as deep hardening.

Autonopedia

Steel Temper Colours

Plain Carbon Steel Only - Hardness Rockwell C

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