Question about spots in steel????

Nathan House

Nathan House

Joined
Feb 14, 2000
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I have a question.I am working with D2 and I have 5 knives finished up,they all came from the same bar of PG D2.
I hand rubbed them out and in one of the knives,there looks like there are water spots in the steel,the other knives did not have this
could there be a bad spot in the steel,or could have somthing else caused it.All the knives but the one hand rubbed out great
(You will see pictures very soon);) What could have caused this
when all the others came out so good:confused: :confused: :confused:
Thanks Nathan
 
I seem to remember someone else having problems with spots on D2 a few weeks ago. I don't remember the forum. I doubt it will affect the steel in any adverse way, but I'm sure you don't like the cosmetics of it.:(
 
Dan
They are spots,they look like a rain drop after it has dryed on a car,I no it is not orange peel,I did not touch a buffer.
I think it was just in that piece of steel,It did not show up until
I started the handing rubbing:confused: :confused:
It ticked off all that work and then to have it show up
bugs me to death.:mad:
 
Nathan
I've seen something like this before
it was a blade from a professional heat treater
no names:( But NO it wasn't Paul B,,

The Blade I looked at was like you said,
it looked to me like it was on a rack of pins maybe
to keep it in the air to heat the top and bottom evenly
and where these pin or rods made contact caused it to temper differently in those spots.
this is my theory in this one case of mine..
Are the spots uniform? in distance from each other and in size?

If all the blades were from the same piece of steel then
I don't think the steel is your problem.

and if you finished off all the (what I call) dead layer from
all the blades and finished all of them the same
I don't feel this is the problem either.
 
Dan
The spots are not uniform,the blade has not been HT yet
I hand sand to 320 before HT,The reason I do this is
on D2 it is really hard to get scratches out after HT
I have found out that when hand sanding the heavy scratches
show up that you don't see with normal belt scratches.I hand sand in one direct,I only grain length ways.The pattern of spots looks like
clouds,but are not a different color than the rest of the bevel.
I am baffled,I no there is not paper loading.This knife has some of my best grinds I have done up to this point.But I will not put my name on it with the pattern in the steel:mad: :mad:
Dan I don't think there are any dead layers in the steel it is Precision Ground stock.:confused:
I am going to grind another knife from this bar on Saturday
I am interested to see if there are any spots in it.:confused:
 
Don't throw the blade away. It can be completed and used for a shop knife. You might have some luck covering the spots up with bead blast, or a scotchbrite finish, ferric chloride, etc.

Look at the spots under high magnification, maybe something will be revealed.
 
I was seeking the cause of one spot like you mention, I was told by Rex that it might be cuased or indicative of a chemical migration that may or may not hurt the overall performance of the steel.
 
Ed
Whay would it show up in only one of the knives I have ground from the same bar.I have 4 others that did not show the marks?
 
Harvy Donaldson, the grand master of bench rest shooting back in the early 1900's stated that each bullet from a lead pot would be different from the one before and the next one. He would place the bullets in a block numbered from 1 to xxx and shoot them in the order they were cast. He believed keeping them in order was important and I recon he was right. If bullets are differert in a simple lead alloy, there will be a difference in steel. The question is, how significant is the difference as a knife?

One end of the bar could have cooled at a diffferent rate, had someting differrent when molten, ? Who knows, if you can see it, it is there. How much difference it makes may be easily determined or unknown. I guess it is like a litter of pups, all individuals. You could find someone from the outfit who made the steel, talk to them and if they sound interested, send them the blade to examine, they may tell you what happened.
 
Ed
Your insite makes alot off sence,I shoot competition archery and I have found that each arrow will fly a little different,even if they are the same weight,fletched the same etc.
I will keep this knife for my own,I do not want to sale it to someone and down the road have a problem with it.Thanks for your helpful input.
Nathan
 
I'll second Ed's reply. I had a talk with Crucible on a similar problem. They explained how variables in the maunfacturing process can cause a flaw to exist, say only on the end of the bar , therefore giving you no problems on the rest of the bar.

Bottom line, if the producer of the steel is open and into customer service, they''ll provide you with a reasonable explanation of what might be the cause - they sell enough of the stuff to have seen these things happen before.

Bob
 
Bob
That was were the D2 came from,it was not at the end of the bar
I still have 9 inches of it left,but it was near the bottom
I hope this does not happen with every bar I get,I hate to put that much work into somthing only to have the steel not work out
to the finish I want.I guess there is no way of getting around it
Like Mr Fowler said it probably happens when the steel is in the moulton state.I will chalk this up as learning something.I imagine
in my knife making I will see it again sooner or later,but I will no what it is
:)
 
Nathan, how are you final finishing the blades? If you are bead blasting them the spots you mention will probably be covered up and you wont see them. I don't think the spots will effect performance either. As time goes by you will run into more and more flaws in all types of material.

I remember a while back I made a fancy folder. When I was about finished I noticed a small spot on the front bolster, kinda like a speck. I have a jewelers loop in the shop to look thru for this very reason. It was a very small hole. So I figured that I could just re sand it out. Well guess what? The hole kept getting bigger! Pissed me off to no end. I ended up covering it up with a nugget finish. In this trade you learn to adapt and improvise!

I was told my my mentor that knife makers don't make mistakes.....Only modifications! ;) Alot of truth in that statement! :)
 
Nathan have you ever done a hammer tone finish on a blade. You get the back of a ball pien hammer and put in a lot of dents. What you will see is if you grind out the hammer marks sometimes you still get spots show through the grind.

I assume it compreses the steel. This is probably just a red hearing but the steel may have been marked before it was ground. Leaving the marks inside.

just guessing
 
Jim
For my final finish I will hand rub it up to 600 grit for a satin finish,I have a 4 Hp air compressor but no blasting cabinet.I will get one when I start working with S30V.As for now I am doing satin finish.
Reg,I have never did a hammer tone,Heck this is only my thrid knife I am trying to finish,but the finish sound very interesting.
Thanks for all the good input.
:)
 
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