Heat Treat, Done Right?

Shorttime · Jan 15, 2025

VorpelSword said:
Pleased clarify that.

Do you mean that their volume of produced knives is small or that they out source a lot of their products? I am not velar on that.

This is one of the debates within our community. Some people mine their own iron sand, cast their own brass, hunt, skin, process, and use the entire elk including the horns for handles.

At the other end are companies that offshore everything except the trucks that convey their merchandise from the ship dock to the store dock.

Since this is a big community, there are always going to be strong, and very specific, ideas about where the transition from "custom" to "mid-tech" to "mass production" happens.

Both CRK and Busse exist in this space where I would call them "mid-tech". If I'm understanding their process correctly, they take a group of knives from start to finish, before going back to work on another group.

Which is where the debate happens. It's easy to say that if your batch size is five knives, then you're still mid-tech. But what if you grow your business until your batch size is a thousand knives?

Is it determined by what your people do? If one person starts a blade and is responsible for all the steps from start to finish, is your company still a mid-tech maker? What if you have five hundred people and the equipment for each of them to do this? I don't think it's a viable business model, but it illustrates the problems of semantics.

It's not a debate I would try to solve, and it's not a debate that I think ever should be solved, because discussing these questions is what keeps our community engaged.

Regardless of where you put them on the continuity from "custom" to "mass production" their heat treat and quality control is very good, and they are well-known examples of both, which makes them easy to point to as places that get it "right", even though both are using very different steels.

DMG · Jan 15, 2025

SharpBits said:
I believe the protocol was shared (or licensed?) with S!. There is a post from Nathan explaining it somewhere here on BF.

I looked it up. Apparently the owner of Survive and Nathan developed it together.

From Nathan:

“Some thoughts about 3V and heat treat:
3V was originally developed for the tool and die industry for difficult stamping applications. The heat treat used in that application, which uses the secondary hardening hump, results in good toughness and abrasion resistance in that application and minimal part growth after heat treat, which is critical in tool and die. But, the carbon lean martensite, secondary carbides and retained austenite that decomposes in temper rather than a part of the primary quench all lead to issues with reduced edge stability in a knife edge. The thin geometry of a knife edge is not found in a stamping tool, and tiny areas of weakness become like the perforations in a postage stamp, allowing an edge to roll over, chip and generally behave "mushy". This sort of thing is so common in today's complex super steels and stainless steels that people just accept it as normal.

We have been tweaking 3V for cutlery for a while now, improving it for knives incrementally. There are a number of versions of these tweaks from me and other makers, but they can all be described as a "low temperature tweak". Basically, it involves avoiding the secondary hardening hump, and when done right reduces structures that are harmful to edge stability, but requires addressing retained austenite without a high temper. A happy side effect of leaving the carbon in the martensite is it doesn't tie up all the chromium, leaving 3V very nearly stainless.

All of my 3V over the years has been tweaked in one way or another.

Last year some of us running a tweaked 3V ran into some trouble with some that didn't respond like we expected. Those of us makers who test work from every batch noticed it. It required some re-work, but we addressed the issue, and it prompted us to try to better understand what was going on with the alloy and to pursue a fully optimized 3V. So, Guy Seiferd (Survive Knives), Dan Keffeler and I invested the time and resources to more deeply investigate variables and develop a more complete understanding of the alloy, its quirks, and develop an optimized heat treat protocol for it. This is one reason my output was low earlier in the year, because I'd spent a significant portion of the winter in R&D mode.

Our previous tweaks to 3V had already made it significantly outperform the industry standard, so the fully optimized version is not a night and day improvement over our previous work, but the difference is significant, so in order to differentiate between this optimized 3V and previous tweaks we are putting a Delta symbol with the 3V on the knife to denote change. Otherwise, it would be difficult to differentiate.”

Thread 'Ten 3V Field Knives, micarta, G10, colors, "Delta 3V" SOLD'

May 6, 2016

The Field Knife was designed as a collaboration with Lorien Arnold. It is a well made, no frills, high performance utility knife. The steel is Crucible CPM 3V at HRC 61-62 with the fully optimized heat treat with very good edge retention and edge stability. You'll be surprised how sharp this gets and how well it holds an edge. If you have never used 3V this hard and thin, it is gonna blow your mind.

This steel with this heat treat will support a fine edge, so this was taken down to .015" before sharpening and it was sharpened 18 degrees per side. This is relatively acute and it cuts...

VorpelSword · Jan 15, 2025

Shorttime said:
This is one of the debates within our community. Some people mine their own iron sand, cast their own brass, hunt, skin, process, and use the entire elk including the horns for handles.

At the other end are companies that offshore everything except the trucks that convey their merchandise from the ship dock to the store dock.

Since this is a big community, there are always going to be strong, and very specific, ideas about where the transition from "custom" to "mid-tech" to "mass production" happens.

Both CRK and Busse exist in this space where I would call them "mid-tech". If I'm understanding their process correctly, they take a group of knives from start to finish, before going back to work on another group.

Which is where the debate happens. It's easy to say that if your batch size is five knives, then you're still mid-tech. But what if you grow your business until your batch size is a thousand knives?

Is it determined by what your people do? If one person starts a blade and is responsible for all the steps from start to finish, is your company still a mid-tech maker? What if you have five hundred people and the equipment for each of them to do this? I don't think it's a viable business model, but it illustrates the problems of semantics.

It's not a debate I would try to solve, and it's not a debate that I think ever should be solved, because discussing these questions is what keeps our community engaged.

Regardless of where you put them on the continuity from "custom" to "mass production" their heat treat and quality control is very good, and they are well-known examples of both, which makes them easy to point to as places that get it "right", even though both are using very different steels.

Thank you for that. I did see a video some time back when Magnicut was just becoming more available. Tim Reeve was talking about how they hadn't introduced it in their line of knives yet as they were still tweaking the heat treatment and balancing how high to go with HRC versus sharpen ability abd toughness. Guess they have got it where they want because I have heard that they now offer Magnicut in every model.

Forty years ago, I made a few knives from scrap spring steel and rusty files while working ofshore in the Persian Gulf. The only heat treat I did then, and about all I could do, was to heat up the blade with a torch and quench it in dirty motor oil.

greater · Jan 15, 2025