Thread: Various Heat Treating Methods Tested

Issue:
I've read too many ways to heat treat, beyond just "quench in oil or brine and bake to temper". Some of the write-ups seem to make sense, but I'd like to see for myself. Partial inspiration for this experiment: "Grain Refinement" on youtube.


Setup:
I took 4 segments of 1/4" O1 drill rod and scored them with a hacksaw (for breaking later).
Each one was quenched:
Quench in Brine: I realize this is O1, so I should have used oil, but I wanted to try brine. I also just cracked a blade I was working on, so maybe not the greatest solution going forward. I heated it to dull red or orange and dunked it, swirling until completely cool.
"Edge Pack" Quench in Brine: Not sure if my method was sound, but I heated it up, waited till it was almost non-glowing and then did some light hammering on the sample. Then I quenched as before in brine, until completely cool.
"3 Step Brine Quench": This is a method proposed by this site (Heat Treatment). Basically, you do a quick dip in brine (less than a second) to get below about 900F, then cool it slowly (about 1 min) until brine no longer sizzles, then let it air cool for about 15 minutes. The theory is that getting to 900F in less than a second avoids perlite, but the "450F to room temp" range is where the martensite actually forms, so give it as long as you can in that stage.
"Edge Pack" & "3 Step Brine Quench": Combined to see if there is additive value.


Results:
When I broke the samples, the first one only required a pair of pliers and the angle of the anvil and hammer. The rest required the sample to be in a vise and hammered transverse. Then I chased down the part that flew across the garage.


The pic attached isn't the greatest, but what I can see with a bench microscope is pretty visible. The different color of the first sample is probably due to rust (it was done a day earlier). With that said, the grain is visible in that sample, much more than in the other samples. Either "Edge Packing" doesn't do much, or I did it wrong, though it seems to have improved grain a little.
Overall, it seems that "3 Step Brine Quench" method produced the most uniform grain - though a little fuzzy in the picture, it makes a pretty nice picture under a scope.


Going Forward:
I want to try again on a blade with the "3 Step Brine Quench." I say again, because I had a practice razor that cracked yesterday. I had worked with sandpaper and got pretty close to an actual edge, which I suspect was my problem. The quench caused some waves in the edge and it also cracked as it cooled. Boo. That goes on the wall in my shop to remind me of my first effort.



Also, who the heck am I?:
I recently got into bladesmithing, I've made a couple of stock removal blades and I recently got my shop setup with a small forge and an anvil. I've been reading a ton about blacksmithing, bladesmithing, razor-making, and anything related - so my head is full of knowledge. Now that my shop is operational, I've begun putting that stuff into practice. I'll hopefully post some info on my next project, which will be a razor out of actual O1 steel (not nicholson file like the last one).

There is no faulting your experimental intention. If you plan to post all this as a journal of your observations, I have a pretty good idea of how it will end. But that is for you to discover.

If you want experienced feedback to shorten your learning curve, there is plenty out there. The first you've already noticed "O-1 should be quenched in oil..." Metallurgists figured that out a long time ago. There are any number of processes that I have tried in my own shop only to discover that the old methods had already eliminated the vast majority of other efforts that wasted time and money trying to solve the equation better.

Good luck.

Like Mike,I like the intention and I am familiar with these methods, I call the 3rd one poor mans marquench although not exactly true it does have the advantage of avoiding thermal shock. For me the methodolgy needs tightening for experimental purposes as there's to many variable to be controled for results to be meaningful. Can't emphasise temperature control enough, mainly the forge but also the quenchant. These things can make significant diferences to the results. You need a way of keeping these things constant from test to test within reason. Having said that, unless you got the steel to hot you wouldn't have grain growth. Thermal cycling would refine the grain though. Hope this helps?

Joe

Joe,
I hadn't heard of marquenching before, but that does pretty much match the procedure I used, though in a much more controlled way. Same general result.
And I agree, temp control is probably my biggest issue. I'm already thinking about how to do that better on my setup. Best idea is "pipe in the forge" for even heat.

Question for everyone:
Say I heat treat successfully using any of these methods on a razor (Defining success as no cracks/warps and the steel achieved hardness). What would the effect of a "better" heat treat be?
Being able to hone it at all?
Keeping an edge longer?
Some other "in use" test (aside from actually doing a Rockwell test)?

I guess I'm mainly looking at how to evaluate my heat treating, once a razor is complete.

Thanks
-paul

If you have simple tools, you have enough. Practice on the blades you make with the tools you have. Make a lot of blades (1000x) until your methods settle into a process where your blades are turning out as good as you can get them with the tools you have in your shop. Otherwise you will begin a chase after "the best" tools and that will never end and it will result in you making only a few blades with very expensive tooling.

Hardness can be simply measured by testing the hardened piece with a semi-used file. If the file bites, the hardened blade is not near Rc 60's. If the file skates you are probably hard enough.

Make razors poorly and the first and most important feedback you will get is from the people who will try to shave with them. Edge durability testing requires time. The second most important feedback is from those who will try to hone these blades. Listen to them both. Then modify your heat treatment process to accommodate them. They are the end users. This last bit will take very little time if you are not making hard enough blades, maybe longer if your blades are too hard. Unfortunately, you are now left with the problem of being patient while the testing runs itself out. There is no quick answer after the blade leaves your shop.

Waiting for end user feedback on honing and shaving performance was my thought too.

Just checking if anyone had other thoughts.

Thanks for your feedback.

I echo all these considerations. Getting an optimal heat treat is not to me necessarily important from an hardness aspect but primarily metallurgical. If you get a matrix of soft structures at the edge(retained austenite or pearlite etc) and or large grains, different wear rates can result in a toothy edge quicker. Great for knives not so much for a razor, but even this is no big deal as long as you don't mind touching up your edges more frequently. You can get a perfectly serviceable edge in the 50's rc though I will concede there is a sweet spot which is a matter of opinion to it's rc value. Some of the customs I have made I can hone as good as my best fili. The difference is my filli is so hard I can go weeks sometimes longer before I need to touch up. In fact I've toyed with the idea of cold forging a blade from a lower carbon alloy to see what kind of edge can be achieved through work hardening alone, this will be a future experiment. My forge kit is dead simple though I do know the blade temperature at any point in time (not the same as control). I still like to squeeze as much as I can out of the process for the reasons I've outlined here.

O1 = not brine

For a razor I do not even play with the process. I have sent to Mike before with good results and my next set will be done either in a salt bath again or an electric HT kiln.

Wisdom is learning from other peoples mistakes. Some of us are the other people.

Jeff

Plus 1
O1 is simple to heat treat, avoid thermal shock if at all possible. Kevin Cashen calls this shocking the snot out of the steel and introduces the possibility of warping or worse. The only time I have used brine to quench is to hedge my bets if using mystery steel or treating very fast shallow hardening alloy like 1095, with thin sections such as razors it's debatable if even this is necessary?
I do think brine is interesting though as speed of quench can be controlled by heating it and can get around the problem of getting your hands on a bucket of parkes 50.

Joe