How to get a Quench line in 5160?

[Karl B. Andersen]

Take Bill up on his offer.
When it comes down to it, he helped to teach me this:

 

[Xrossbarlock]

I too have heard that you can not get a good hammon line with 5160 steel but I just made a skinner for a customer and decided to etch it after sanding to 600 grit finish.

The temper line was very bold and also revealed a Damascus like area directly above the martinsite edge. The spine of the blade reveals nothing.

My mineral oil quench tank is heated with a thermostat controlled water heater coil and I have installed a pump with double outlets to create flowing oil over the edge stop plate.

If your blades are breaking all of the way across the blade after edge quenching, I would seriously over haul your heat treating process.

For starts you will want to look at your temperatures for normalizing and hardening.

I also think that a lot of folks are not allowing the steel to get into complete solution prior to hardening.

Here is what can happen to your steel: You have forged and ground the blade into shape and then you give it a nice slow annealing to take out all of the stresses created by grinding and pounding it into shape. This lets the carbon and other impurities to migrate out of solution and form into clumps or spherical balls.

Now you heat the blade to critical and let it cool to tighten up the grain several times and then at last you heat to critical and quench.

Now if you are following me, you should be wondering what the carbon etc. is doing at this critical point.

It took time to anneal the blade and this time allowed the carbon to pool and if you harden the blade in this condition, the carbon will do every thing bad and nothing good. Grain boundary embrittlement is a factor to consider.

It also takes time to put the carbon back into solution and this should be done just previous to the normalizations. Soak the blade just above critical for a minimum of 20 minutes and this will give you dazzling results.

 

[Bailey Knives]

I am certainly not an expert on this, but I do a lot of hamons. To get an active hamon, use simple steels, 1095, 1084 (my favorite), W1. I coat the back edge with rutco's furnace cement, then mess the edge of it up with a tiny metal spatula. Heat treat it normally, and I quench in Parks 50. They tend to be kind of hit or miss. I always get a hamon, but sometimes you can see the whispy cloudiness between the hardened and softer steel, and sometimes you cant. I just made one with 1095, that has really great activity, and I have used the same steel, and the same process in the past and it turned out to be kinda boring.

It is also important to bring it up to a decent polish before etching. I normally hand sand to 1000 or 2000, depending on the type of knife.