Question on o-1 blade

arrow-360

arrow-360

Well-Known Member
I heat treated 4 blades, to rockwell of 59. I am mirror finishing one, that took a nice mirror finish. But... In the right light, and angle it seems to be covered with little pits. Can these be taken out, or do I just have to live with them? Is it just o-1 or is it just me? I started wet sanding with 220 and went through the grits all the way to 2000 and than buffed, no scratches can be seen. I am quite new to knife making, and didn't notice it on my first blade because I left it a satin finish. Would be greatfull for any advice.
Dave
 
Last edited:
If I can remember correctly it can occur when there is too much heat used when heat treating, but I'm sure there aree other causes as well.
 
Thanks!!!

OK, Thanks for the replys!
The pits are very very small. Looks more like cloudyness, to naked eye. Using a magnifying glass reveals pits. Looking straight into it looks like a mirror. As far as being to hot during heat treat.. They were heat treated at work, whith an oven that was just calabated. Treated at 1475 and tempered twice at 450. Should have been very accurate. I could just start to see them at 2000 grit. I will try going through the grits again in a small area, and see if it improves or maybe even goes away. We rockwell tested them, and they came out exactley as I wanted, at 59. Will post the results this weekend when I have a chance. Thanks again!
Dave
 
Last edited:
Results!!!

Found a few minutes, and worked through some grits starting at 360 and ended with a quick buff.... Nearly all pits are gone!:D I think if I do a good job through all the grits, it will be fine. I was real afraid that my heat treat went wrong, but everything will turn out great.
Thanks to all!
Dave
 
Last edited:
Two questions Dave,

What temperature was your quench oil when you quenched. And How long did you hold the temp?

Too low or high a quench oil temp can affect grain growth.

And all of the oil quench/deep hardening steels are VERY soak sensitive. Either thing can effect grain growth and may result in blemish when polished that finely.

If you can't live with it and don't mind playing with um before re treating them, try re sanding one of the blades with like 800 grit instead of the super fines and then buffing them again and see what that does. Got a feeling they will go away.
 
JDB said:
Two questions Dave,

What temperature was your quench oil when you quenched. And How long did you hold the temp?

Too low or high a quench oil temp can affect grain growth.

And all of the oil quench/deep hardening steels are VERY soak sensitive. Either thing can effect grain growth and may result in blemish when polished that finely.

If you can't live with it and don't mind playing with um before re treating them, try re sanding one of the blades with like 800 grit instead of the super fines and then buffing them again and see what that does. Got a feeling they will go away.
Click to expand...

My quenching oil was at about 140 degrees. I held temp at 1475 for around 20 minutes, quenched for about 15 secounds, let cool to around 125 degrees and baked at 450 for two hrs, let cool, and baked again at 450 for two more hours.
Thanks for the reply!!!
Dave
 
JDB said:
Two questions Dave,

What temperature was your quench oil when you quenched. And How long did you hold the temp?

Too low or high a quench oil temp can affect grain growth.

And all of the oil quench/deep hardening steels are VERY soak sensitive. Either thing can effect grain growth and may result in blemish when polished that finely.

If you can't live with it and don't mind playing with um before re treating them, try re sanding one of the blades with like 800 grit instead of the super fines and then buffing them again and see what that does. Got a feeling they will go away.
Click to expand...

By the way! If they dont come out, can I retreat to get rid of them? I would cut temp to around 1450.
I don't think I will be putting mirror finnish on to many blades. A guy at work I am making it for wants a mirror finish.
Dave
 
Last edited:
That process sounds about right from what I can remember Dave. Maybe the calibration could be off as you said.

And yeah, you can re treat them, but if you don't find the problem it may just do the same thing again. Not sure reducing the heat will do it. You really need to stick to the manufactures recommendations though. And off the top of my head I was thinking you had it right the first time.

I don't do a lot of oil quench steels. Mainly because I don't have a real oven. It's a pain to hold heat that long with a forge. Maybe Ed or one of these guys that use oil quench steels will come along with a definitive answer. It may be a quark of the steel and not in the heat range at all.

I wish I could be of more help Dave. It's not anything I've seen before. I suspect it's why most instructors don't recommend starting with O1 though. LOL

As I said, if you are going to re heat treat them anyway, try roughing one down with 800 grit and polish it again first. I know it sound crazy, but it may work and can't hurt.
 
I have get small arrow liked pits when i polished and it got to hot. But you had it before.

Seved
 
You must log in or register to reply here.
Back
Top