Too soon from quench to temper?

S

Snakepoint

Joined
Feb 26, 2023
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Hi. Newbie with a newbie question here. I’m wondering if I placed a knife into temper too quickly after quenching.

Steel 1080 blade.
Normalized blade three times.
Heated again for a minute plus after non-magnetic.
Quenched immediately in 135 to 140 degree canola oil plunging blade straight up and down for a minute.
Wiped blade off and file skated nicely.
I walked into the house to put it in the oven. Here is my dilemma. I’m not sure if I let it actually cool down enough before I put it in the oven to temper. I got ahead of myself and didn’t let it cool down to ambient temperature. Did I ruin my heat treat? Can I normalize and go through the heat treat quench process again? I’m hoping the blade had time to cool below 400 with a minute of plunging in the canola, then skate test, then walking from outdoor garage to house. Does it have to cool all the way down to ambient before temper or is above ambient and below 400 good enough? Thoughts? Thanks I’m advance.
 
I don’t know that I’ve heard anything about this other than some air hardening steels recommend tempering as soon as the blade is cool to the touch. You might want to try a faster quench. Canola can have issues with simple steels like 1080.
 
That one will probably be ok. You can do better but since your learning it's not worth panicking.
It is better to get them as cold as practical to minimise retained austenite (not a major issue with 1080). This is why some people will do a cryogenic treatment before the 1st temper.
You can probably re-heat treat that knife if you want

I assume your temperatures listed above are Fahrenheit?
 
Thank you. It was a learning experience that I will not forget. This is my second blade. I’m sure I’ll have quite a few more learn it the hard way experiences.

I have some Parks 50 on the way!

Best regards,
 
One minute was more than enough. canola oil will still be smoking at 400, so if it wasn't smoking when you were walking to your house your probably just fine.. I like to get them into the temper as soon as I can. I go with about a 10 second quench, then straight into the quench plates to minimize warping, then right to temper. If you had it in the oil for an entire minute, I bet it was under 200.
 
I'm not trying to nit pick you here, but something to consider. Normally, "normalizing"is done one time, you may be referring to something called "thermal cycling" which would go through 3 or four cycles. I don't think you have any problem with your tempering timing, but if you normalized 3 times, then quenched, you will have put your steel through 3 cycles of grain growth and then locked that in. You have to thermal cycle your steel after you normalize it. Maybe that's what you were referring to. Again, I'm not trying to beat you up on terminology, just asking what you meant by normalizing?
 
With 1080 the Ms is around 400°F. The Mf is around 200°F. It is best to cool it to below 100°F. but I am sure your blade is fine.
I wash the oil off on all my blades in running cold tap water and dry them before tempering. This assures them to be well below the Mf on carbon steels. High alloy and stainless steels need to drop to -100°F before temper (or lower).
 
I've seen a video that showed Canola oil did not achieve a 60+ hardness all the way through blade (center) on 1084 Steel Knife blade 1/4" and was showing 40-45 hardness 0.03" depth. While on surface it could be 60-65 and guard against a file. It was showing Parks 50 did and so did Water quench.

But if I decide to use water I'd like to know if distilled is best and how do you do the two stage quench using water then canola oil?

Has anyone cut the blades in half after quenching to test hardness of center or checked at least the outside in various areas?
 
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Water is water as far as quenching. Slack bucket water, creek water, rainwater, distilled, tap - all the same.

Brine quenching is a skill. You will probably "ping" a few blades learning it.

Getting a gallon or two of Parks #50 will give you assured quenches for most every carbon knife steel for a long time.
 
Yes indeed ... even thumbs have rules ... and rules have thumbs.

While the word "inch" comes from a Latin word meaning 1/12th (of a Roman foot), the measurement was deemed "the width of a man's thumb."
 
You can thank the French revolutionaries for that.
They hated everything about the "Old Government" so much they created a new calendar, new time system, and a new system of measurements in 1795. The calendar and time changes did not last long ... but the measurement system was what science had been looking for. The entire change happened in two years!
They formed a system based on powers and inverse powers of 10. Measurement was in meters ... from the Greek word metros meaning measurement. Volume was based on liters ... from an old Greek word litra, meaning "pound" (that is why the British pound uses an £). Originally, it was the weight of a certain volume of water (roughly a pint). The French scientists came up with a new volume based on the meter. One cubic centimeter of water was one gramme, and 1000 grammes of water was a liter. Thus, for the new weigh system, a kilogram became the weight of 1 liter of water.

But this new length of a meter was not precisely based on any exact length .... they did not want an arbitrary length based on some emperor's arm or footstep length ... they wanted science! So, to figure out exactly what a meter was, two French astronomers spent nearly a decade determining the distance from the north pole to the equator on a meridian running through Paris. The meter would be 1/10,000,000 of that distance. A kilogram weight and a meter long rod were then made in platinum and stored in a vault outside of Paris. The international standards are still stored there.

Today we use atomic references to determine most measurements, but you can thank a handful of irate Frenchmen for the metric system.

I so wish the USA had changed to metric when it first tried. How much is 1/2 of 7feet 3 and 9/36inches ??? Who knows? But how much is 1/2 of 2.22 meters - 1.11 meter ... easy peasy!
 
It somewhat defies logic to many of us.
In 1800 the new American government loved France.
Ben Franklin and Thomas Jefferson framed the constitution and wrote the Bill of Rights. They were both scientists. They loved France.
Science was sweeping the world with The Age of Enlightenment. The world turned their eyes toward France and French scientists.
We kicked the British out and changed many of their ways and rules....... But said "Merci, Noin!" to the French new system.

And we kept the non-meshing Imperial measurement system of pounds, ounces (volume, avoirdupois, troy ... which don't correlate to each other at all), pints (imperial and standard), tons (long and short) inches/feet/yards, leagues, miles (nautical and statute), acres, hectares, etc. We could have adopted the French system easily. There would be some changes to make and land deeds to adjust, but by the early 1800's we would have been free from the English tyranny of measurement.
 
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