Recommendation? SS foil heat treating decarb depth

[Skiller1nc]

After searching the forum I haven't been able to find any answers to this specific question.

When heat treating higher alloy steels like d2 in foil and plate quenching, what kind of decarb depth is typical?

I'm making some hunters and I want a 20 thou bte thickness, I've seen many recommendations on the forum saying you can grind to 10-20 thou pre ht for d2, however, if there is 5 thou decarb (just a guess) and I grind to 20 pre ht that will end up too thin.

 

[Stacy E. Apelt - Bladesmith]

You should always leave a little extra width on the edge to grind back in final shaping. This also removes any edge decarb.

Properly wrapped in foil, the decarb is probably very shallow.

 

[Willie71]

After searching the forum I haven't been able to find any answers to this specific question.

When heat treating higher alloy steels like d2 in foil and plate quenching, what kind of decarb depth is typical?

I'm making some hunters and I want a 20 thou bte thickness, I've seen many recommendations on the forum saying you can grind to 10-20 thou pre ht for d2, however, if there is 5 thou decarb (just a guess) and I grind to 20 pre ht that will end up too thin.

if the foil is properly sealed, decarb will be very thin. Thin enough that I don’t see much difference in RC testing before and after grinding the surface of the blade. I’m guessing a couple thousandths of an inch at most.

0.020” is pretty thick for a skinner. I use 0.010” or thinner, depending on the steel.

 

[Nick-D]

if the foil is properly sealed, decarb will be very thin. Thin enough that I don’t see much difference in RC testing before and after grinding the surface of the blade. I’m guessing a couple thousandths of an inch at most.

0.020” is pretty thick for a skinner. I use 0.010” or thinner, depending on the steel.

+1 10 thou bte is perfect for a hunter imo, can go thinner on some steels but as a general rule 10 thou is hard to go wrong. See way to many hunters that are far to thick bte.

 

[Skiller1nc]

Thanks for the advice all, the knives are d2 steel, I HTed one yesterday as a test blade and it was 10 thou pre ht. I'm going to clean it up and run it through some tests today.

I had another question. When you make a knife, say a d2 hunter. If you know your ht is good as can be for d2 and say you temper to 60rc.
If during testing the blade chips. How do you know whether to a. temper at higher temp b. increase secondary bevel angle c. increase bte thicknes or some combination on those

 

[Willie71]

Thanks for the advice all, the knives are d2 steel, I HTed one yesterday as a test blade and it was 10 thou pre ht. I'm going to clean it up and run it through some tests today.

I had another question. When you make a knife, say a d2 hunter. If you know your ht is good as can be for d2 and say you temper to 60rc.
If during testing the blade chips. How do you know whether to a. temper at higher temp b. increase secondary bevel angle c. increase bte thicknes or some combination on those

If the heat treat was right, it shouldn’t chip at 0.010”.

 

[Skiller1nc]

If the heat treat was right, it shouldn’t chip at 0.010”.

humor me, if an edge is chipping, what would be the parameter you change? Basically, I'm asking, since all 3 aspects affect performance, how do you decide which to change? I would say if cutting performance will be affected by thickening the edge then you need to temper higher, however, if you can thicken w/o hurting cutting performance then do that b/c you want as hard an edge as possible. Is that logical?

 

[Stacy E. Apelt - Bladesmith]

You haven't told us what we need to know about the question.
1) How was hardness determined? - If you are just guessing the hardness based on HT parameters, you really don't know how the HT came out.
2) How was the HT done? - Temps, methods, quench . etc. We can't tell you where to go if we don't know where you came from.
3)What was the temper done at? - We can't tell you where to go if we don't know where you are.
4) What is the edge angle? - We can't tell you how much you may need to change if we don't know the angle.
5) What were the tests that caused chipping?


Normally, with what you told us the recommendation would be to temper at 25 degrees higher to reduce chipping, and test again.

 

[Willie71]

humor me, if an edge is chipping, what would be the parameter you change? Basically, I'm asking, since all 3 aspects affect performance, how do you decide which to change? I would say if cutting performance will be affected by thickening the edge then you need to temper higher, however, if you can thicken w/o hurting cutting performance then do that b/c you want as hard an edge as possible. Is that logical?

If it chips at that geometry, change your heat treat. It wasn’t done right. Nor sure how else to answer that.

 

[Skiller1nc]

You haven't told us what we need to know about the question.
1) How was hardness determined? - If you are just guessing the hardness based on HT parameters, you really don't know how the HT came out.
2) How was the HT done? - Temps, methods, quench . etc. We can't tell you where to go if we don't know where you came from.
3)What was the temper done at? - We can't tell you where to go if we don't know where you are.
4) What is the edge angle? - We can't tell you how much you may need to change if we don't know the angle.
5) What were the tests that caused chipping?


Normally, with what you told us the recommendation would be to temper at 25 degrees higher to reduce chipping, and test again.

Sorry for being unclear, the knife in question hasn't chipped or anything, I was just wondering/looking for insight into how you go through these testing steps yourselves. Being that there are 3 ways that can be used to help in this situation I was wondering how you go about choosing which variable to change. I was just getting ahead of myself in case it did chip or have other problems.

The knife itself is a 7-inch drop point style 0.120" thick at the spine hunter/bushcraft
1. the d2 was hardened in foil in HT oven, it is aks d2, put into 1850f oven for 45 minutes. plate quenched and tempered at 500f, Rockwell tested on tang at 60.
2. the bevel is 4 degrees per side, .01" bte, and the secondary is 20 degrees.
3. chopping and batoning through an old/dry 2x4 and cutting cardboard had no detrimental effect on the edge

 

[Willie71]

Sorry for being unclear, the knife in question hasn't chipped or anything, I was just wondering/looking for insight into how you go through these testing steps yourselves. Being that there are 3 ways that can be used to help in this situation I was wondering how you go about choosing which variable to change. I was just getting ahead of myself in case it did chip or have other problems.

The knife itself is a 7-inch drop point style 0.120" thick at the spine hunter/bushcraft
1. the d2 was hardened in foil in HT oven, it is aks d2, put into 1850f oven for 45 minutes. plate quenched and tempered at 500f, Rockwell tested on tang at 60.
2. the bevel is 4 degrees per side, .01" bte, and the secondary is 20 degrees.
3. chopping and batoning through an old/dry 2x4 and cutting cardboard had no detrimental effect on the edge

Yup. Proper heat treat, at that geometry, no problems for normal use.

 

[Willie71]

Basic evaluation:

if it’s chipping, it’s too thin or hard, if it’s rolling, it’s to thin or soft.