View Full Version : Heat treating 17-4 pH for color vs. condition???

02-05-2012, 10:20 PM
I am making some parts out of 17-4 pH purely for cosmetic reasons (they will be part of a gift). . .I chose 17-4 because of how easy it is to get long lasting coloration out of it.

I have heat treated 17-4 at work quite a bit in the past, but always to H900 condition. . .I am used to getting the dark brownish/gold color with slight hints of purple.

Does anyone know what temperature I should heat treat 17-4 at in order to get more purple from it?


I'll post pic's after I'm done with it. . .

Alan Douglas
02-07-2012, 08:11 PM
I don't know, but perhaps can bump your question back up in the queue by replying. Back when we had a shop where I work, before we had everything made outside, we used 17-4 often. I made a bench block from it which I still use. We made underwater pressure housings.

02-08-2012, 01:50 AM
I hate to be the one to tell you, but becausce 17-4is a precipitation hardening alloy and the precipitation doesn't happen untill 900 degrees you probably won't find many people that have heat treated to lower temps to give you the information you want. You will probably have to experiment. If you have a furnace, mabe start at 500F and go up from there in 50 degree increments untlil you get the oxide colors you want. If you are doing with a torch it will be much harder but should still be doable if you apply the heat slowly. Will be tough if you have to repeat the results a lot though.

Tony Wells
02-08-2012, 02:02 AM
If the surface is clean, and you run it in a vacuum, there is very little discoloration. However, most heat treaters don't run their aging in a vacuum as a standard practice. That's why you see varying colors in the PH steels. I've seen 17-4 @ H900 all over the map. Brown to shiny to blue/purple. Same with H1150. Seems more blue/purple than the H900, and a bit more gold/brown with the H900.


02-08-2012, 07:47 PM
Thanks for the help. . .I went H900, I had some nice blue and purple highlights initially, but as the part cooled I ended up with a nice gold with some reddish hints. . .

I used an oven without vacuum.

I will post some pic's of this up later. . .it's a Valentine's gift for my GF.

02-08-2012, 08:11 PM
You need a lower temp to stay in the blue/purple range.

02-10-2012, 11:42 PM
I was hoping for more purples and blues than this, but it looks nice and I'm sure she will like none the less. . .oh well, live and learn right.



If I had more time before Valentine's Day I would have heat treated a bunch of coupons and figured out which temp. gave me the look I wanted, but I didn't have the luxury of time. . .on a side note, it had some really nice blue, purple, and red highlights initially that faded once it cooled down to room temperature.