heat treating S5 steel

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katanadude

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Jul 19, 2012
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Is any one here experienced with heat treating S5 tool steel? I need a piece heat treated to 59 to 60 rc with a good cryo treatment if possible.
 
Since no one has replied...I don't work with it, but the HT is:

Stress relieve at 1200-1245F for 1 hour and cool in air.

Harden by preheating slowly to 1400F , then bring to 1650F and hold for 5 minutes. Quench in oil. As quenched hardness is 58-61.

Temper IMMEDIATELY at 350F, twice.

It can be water quenched from 1580F for the higher hardness ( 61-62). Tempering IMMEDIATELY is very important if water quenched.
 
I actually brought back the book i use at work for h.t. info just to answer this. That said i defer to stacy in this.

from heat treatment, selection, and application of tool steels:

s5: no reference on stress relieving

preheat to 1200f hold for 10 min.

then to 1725f hold 10 min.

quench in 150f oil for an as quenched hardness of 61

temper immediately upon reaching 150f

temper 3 times reducing temperature by 25f increments each successive heat. e.g. 350 then 325 last 300

one hour minimum per temper, 2 hours ideal

like stacy, i've never h.t. s5 before so this is just textbook stuff and its not a h.t. specifically for knives so i'd go with stacy's given his extensive knowledge of this stuff.
 
Those parameters are most likely for larger pieces in much thicker sections. The numbers I used were extrapolated for knife thicknesses and use. I used the ASM Heat Treater's Guide.

As you can see from the two sets of numbers, S5 needs a higher austenitization and a soak time to get the alloy ingredients into solution. It needs to come just up to the austenitic start and rest for a short time beforehand. It is very unstable, and can crack easily once reaching the Mf if not tempered immediately. Once tempered fully, it is a reasonably hard and very tough steel.
 
Thanks guys and do either of you know what the hardness would be after tempering? I'm going to assume around 58 if it was hardened to around 59 to 60 by and oil quench and maybe 59 to 60 if hardened to 61 to 62 with a water quench. If this is the case I probably need it water quenched to get the hardness I need but it sounds really tricky and I don't was want to mess up the temper or lose significant toughness I could other wise be getting with this grade of steel.

So if any one would like to take this heat treat on let me know.
 
This isn't a hard steel, it is a tough steel. I would not suggest a water quench in blade thicknesses. After temper, figure a hardness of 56 to 58, depending on how well the quench went.
 
bladsmth said:
This isn't a hard steel, it is a tough steel. I would not suggest a water quench in blade thicknesses. After temper, figure a hardness of 56 to 58, depending on how well the quench went.
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wow that's it, I guess it makes sense though if it can only get to 60 with an oil quench, I really wish I could do a water quench so it could be a little harder after temper but as you say it might not be wise in the thickness of a blade.

I wonder what about for a sword or thick machete tho like say 1/4 an inch?
 
Make what you wish, but selecting the steel for the task should be the way to start. S5 and S7 are good steels for choppers and rough use knives and camp tools, but there are probably better steels for a sword and others that work well for a machete.
I would take a look at 5160, 3V, A2, and 1070/75/84.
 
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