Color Coding On Steel

[Whyemier]

I have some steel pieces color coded with a violet/purple end. I know this designates the type of steel. (I've forgotten more than I ever knew about steel types) They're both hot rolled (I believe) one 3/4" and one 2 1/4". I had thought they were 1018 or 12L14 but they don't cut the same as the other 1018 and 12L14 I have. (I had purchased a 'Lot' of 12L14 & 1018 off E-bay).

The surface cut seems to pull when facing or turning, as if the tool is dragging the metal up the surface. I was running at 300-350 rpm. Slower than I usually cut the steel I have. The chip was turning blue with .008 & .014 feed. I should have taken a photo but didn't. I thought it might be the HSS bit I was using and changed to carbide. I checked to make sure the tool was on center. Nothing helped get a better surface. I've not had this problem with the other steel I have, I thought it was all the same. I think this was a different grade as it seemed tougher.

I finished it off with a Heller file and then a Bastard file then 100/220/320 grit emery. So the surface is acceptable now but I just turned another piece and got a better surface finish with just a carbide tool bit and some 220 grit emery.

Any idea what steel this could be?

 

[Whyemier]

OH! Just checked online and found a color chart. (shoulda done that first). They are both 4140. Must have been some drops in that 'Lot' I bought. Wish I had checked earlier, I would have saved those pieces out for 'special' projects. Have to look and see if I have more of that.

 

[JimDawson]

I was going to say 4140 also, but the color code depends on the supplier. Most of the speciality metals come from one vendor in my area and they have a published color code. I have seen the same alloys from other vendors, that had different markings. As far as I know there is no set industry standard.

 

[4GSR]

......... As far as I know there is no set industry standard.

That is absolutely correct. Every steel vendor has their own color code system. Some may share certain colors for certain grades but in general there is no one set system used in industry. A company I worked for back in the 1980's- 1990's had their own color code system that they used in house for identifying various grades of material, conditions, special requirements, etc. Made it nice rummaging thru their short end rack for something to use for a government job!

 

[george wilson]

I wish color coding steels consistently would become REQUIRED. This is like the days before standard tolerances for thread sizes became standard,and everyone fought to screw things together. Not well worded,but you get my meaning.

I have a bunch of steel bars with red,lavender and purple ends painted on them. The only thing I could do was cut off samples and heat treat them,keeping notes as to which would harden and how much. Good for non essential work. These steel bars all came from the same source,but I have no way of knowing what that source WAS.