Bashed a blade out from an old file (by hand, no power hammer!) then onto the grinder, and 8 hours later it looked like this,..... I was pretty pleased at this point, forging good, grinding improving a bit, tripple normalised to control the grain size, . yup, well on its way to being a proper knife, had a bit of a guess it was a 'w' series steel, so clay backed it and into the water...... 3 seconds later it looked like this,......

The moral of the story is probably test H.T. a bit of the steel before you chuck a perfectly serviceable blade into a bucket of water :rolleyes:

Edited July 15, 200916 yr by mod07
pic resize, and Funny enough moved to Blade HT

That is a shame..however for those of us looking...wot a nice set of pics,, really well done. Thanks

John, started out really nice. A shame but it happens to all of us. Thanks for posting it here; some of the beginning blade smiths can learn from it.

Been there done that and still do once in a while, keep experimenting and have fun
I know it's discouraging but you will get used to it if you want quench in water.

Bob
By the way that was a nice looking blade!

Is an oil quench less prone to fracture? I know some metals are meant for oil quench and others are meant for water quench. Could this be an example of the wrong quench being used? Is there an easy guide to decide what quench agent to use?
I know quenching causes stress in the metal. Will holding the part at temperature for a long soak (5-10 min or so?) instead of getting temperature color and quench be better?
I have had terrible luck with heat treating, even when assisted by a lab aid in school. At least a process failure did not affect the grade as long as it could be remade that semester.
Phil

What quenchant you use is based on what alloy you use *and* note that most of the professional information is based on a 1" cross section. With knives you often back up one in the quenchant list as we are using much smaller cross sections. So a water quenching steel may do fine in a fast oil quench, an oil quenching steel may actually harden with an air quench, etc.

If you don't know your alloy make a sample piece the same size as a blade and test it on various quenchants starting with the most mild. Stop when you get the hardness you want and then test tempering temperatures on it. A lot of work but if you want to use scrap it's the price you pay!

I tell my students to expect to ruin their weight in steel learning patternwelding and knifemaking!

Most of the time water is used for bigger pieces with a large cross section most water hardening steels recommend oil for small pieces.
To your second question yes anything that is higher carbon or alloyed steel will greatly benefit from a soak at a crontroled temp.
Bob

mmm. i dont like files. i had one quenced in oil then differentially tepmperd to a blue on the spine and bronze at the edge, after a couple of light chops on a logg of wood it snapped. a close inspection of the grain showed no real difference from edge to spine.
so now i just leave my file knives nomalised and they seem to hold up reasonably well.

same thing happened to me last night, using simple high-carbon steel (approx 1090), except I edge quenched in water. Two separate deep running cracks started at the edge. A second knife was fully emersed in water w/o problem.

I wish this were a better science rather than a crap shoot

same thing happened to me last night, using simple high-carbon steel (approx 1090), except I edge quenched in water. Two separate deep running cracks started at the edge. A second knife was fully emersed in water w/o problem.

I wish this were a better science rather than a crap shoot

This is the main reason why we use a fast oil, not water for high carbon, remember that the spec sheets are for 1 inch thick sections, not the 1/8 blades. Mineral oil can give a hamon. Water many times will crack 1080 and higher carbon steels. Mystery steels including old files, need testing before we dump it in water and ruin it. Some old Files may be F-1 and tungsten doesn't like water at all.